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/* |
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* Copyright (c) 1997, 2007, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Sun designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Sun in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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|
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package java.util; |
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import java.io.Serializable; |
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import java.io.ObjectOutputStream; |
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import java.io.IOException; |
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import java.lang.reflect.Array; |
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|
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/** |
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* This class consists exclusively of static methods that operate on or return |
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* collections. It contains polymorphic algorithms that operate on |
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* collections, "wrappers", which return a new collection backed by a |
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* specified collection, and a few other odds and ends. |
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* |
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* <p>The methods of this class all throw a <tt>NullPointerException</tt> |
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* if the collections or class objects provided to them are null. |
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* |
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* <p>The documentation for the polymorphic algorithms contained in this class |
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* generally includes a brief description of the <i>implementation</i>. Such |
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* descriptions should be regarded as <i>implementation notes</i>, rather than |
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* parts of the <i>specification</i>. Implementors should feel free to |
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* substitute other algorithms, so long as the specification itself is adhered |
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* to. (For example, the algorithm used by <tt>sort</tt> does not have to be |
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* a mergesort, but it does have to be <i>stable</i>.) |
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* |
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* <p>The "destructive" algorithms contained in this class, that is, the |
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* algorithms that modify the collection on which they operate, are specified |
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* to throw <tt>UnsupportedOperationException</tt> if the collection does not |
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* support the appropriate mutation primitive(s), such as the <tt>set</tt> |
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* method. These algorithms may, but are not required to, throw this |
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* exception if an invocation would have no effect on the collection. For |
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* example, invoking the <tt>sort</tt> method on an unmodifiable list that is |
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* already sorted may or may not throw <tt>UnsupportedOperationException</tt>. |
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* |
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* <p>This class is a member of the |
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* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
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* Java Collections Framework</a>. |
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* |
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* @author Josh Bloch |
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* @author Neal Gafter |
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* @see Collection |
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* @see Set |
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* @see List |
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* @see Map |
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* @since 1.2 |
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*/ |
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|
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public class Collections { |
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// Suppresses default constructor, ensuring non-instantiability. |
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private Collections() { |
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} |
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|
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// Algorithms |
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|
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/* |
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* Tuning parameters for algorithms - Many of the List algorithms have |
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* two implementations, one of which is appropriate for RandomAccess |
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* lists, the other for "sequential." Often, the random access variant |
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* yields better performance on small sequential access lists. The |
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* tuning parameters below determine the cutoff point for what constitutes |
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* a "small" sequential access list for each algorithm. The values below |
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* were empirically determined to work well for LinkedList. Hopefully |
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* they should be reasonable for other sequential access List |
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* implementations. Those doing performance work on this code would |
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* do well to validate the values of these parameters from time to time. |
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* (The first word of each tuning parameter name is the algorithm to which |
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* it applies.) |
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*/ |
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private static final int BINARYSEARCH_THRESHOLD = 5000; |
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private static final int REVERSE_THRESHOLD = 18; |
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private static final int SHUFFLE_THRESHOLD = 5; |
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private static final int FILL_THRESHOLD = 25; |
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private static final int ROTATE_THRESHOLD = 100; |
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private static final int COPY_THRESHOLD = 10; |
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private static final int REPLACEALL_THRESHOLD = 11; |
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private static final int INDEXOFSUBLIST_THRESHOLD = 35; |
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|
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/** |
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* Sorts the specified list into ascending order, according to the |
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* {@linkplain Comparable natural ordering} of its elements. |
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* All elements in the list must implement the {@link Comparable} |
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* interface. Furthermore, all elements in the list must be |
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* <i>mutually comparable</i> (that is, {@code e1.compareTo(e2)} |
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* must not throw a {@code ClassCastException} for any elements |
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* {@code e1} and {@code e2} in the list). |
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* |
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* <p>This sort is guaranteed to be <i>stable</i>: equal elements will |
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* not be reordered as a result of the sort. |
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* |
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* <p>The specified list must be modifiable, but need not be resizable. |
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* |
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* <p>Implementation note: This implementation is a stable, adaptive, |
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* iterative mergesort that requires far fewer than n lg(n) comparisons |
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* when the input array is partially sorted, while offering the |
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* performance of a traditional mergesort when the input array is |
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* randomly ordered. If the input array is nearly sorted, the |
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* implementation requires approximately n comparisons. Temporary |
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* storage requirements vary from a small constant for nearly sorted |
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* input arrays to n/2 object references for randomly ordered input |
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* arrays. |
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* |
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* <p>The implementation takes equal advantage of ascending and |
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* descending order in its input array, and can take advantage of |
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* ascending and descending order in different parts of the same |
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* input array. It is well-suited to merging two or more sorted arrays: |
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* simply concatenate the arrays and sort the resulting array. |
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* |
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* <p>The implementation was adapted from Tim Peters's list sort for Python |
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* (<a href="http://svn.python.org/projects/python/trunk/Objects/listsort.txt"> |
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* TimSort</a>). It uses techiques from Peter McIlroy's "Optimistic |
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* Sorting and Information Theoretic Complexity", in Proceedings of the |
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* Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, pp 467-474, |
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* January 1993. |
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* |
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* <p>This implementation dumps the specified list into an array, sorts |
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* the array, and iterates over the list resetting each element |
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* from the corresponding position in the array. This avoids the |
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* n<sup>2</sup> log(n) performance that would result from attempting |
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* to sort a linked list in place. |
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* |
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* @param list the list to be sorted. |
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* @throws ClassCastException if the list contains elements that are not |
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* <i>mutually comparable</i> (for example, strings and integers). |
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* @throws UnsupportedOperationException if the specified list's |
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* list-iterator does not support the {@code set} operation. |
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* @throws IllegalArgumentException (optional) if the implementation |
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* detects that the natural ordering of the list elements is |
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* found to violate the {@link Comparable} contract |
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*/ |
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public static <T extends Comparable<? super T>> void sort(List<T> list) { |
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Object[] a = list.toArray(); |
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Arrays.sort(a); |
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ListIterator<T> i = list.listIterator(); |
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for (int j=0; j<a.length; j++) { |
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i.next(); |
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i.set((T)a[j]); |
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} |
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} |
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|
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/** |
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* Sorts the specified list according to the order induced by the |
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* specified comparator. All elements in the list must be <i>mutually |
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* comparable</i> using the specified comparator (that is, |
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* {@code c.compare(e1, e2)} must not throw a {@code ClassCastException} |
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* for any elements {@code e1} and {@code e2} in the list). |
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* |
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* <p>This sort is guaranteed to be <i>stable</i>: equal elements will |
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* not be reordered as a result of the sort. |
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* |
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* <p>The specified list must be modifiable, but need not be resizable. |
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* |
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* <p>Implementation note: This implementation is a stable, adaptive, |
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* iterative mergesort that requires far fewer than n lg(n) comparisons |
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* when the input array is partially sorted, while offering the |
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* performance of a traditional mergesort when the input array is |
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* randomly ordered. If the input array is nearly sorted, the |
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* implementation requires approximately n comparisons. Temporary |
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* storage requirements vary from a small constant for nearly sorted |
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* input arrays to n/2 object references for randomly ordered input |
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* arrays. |
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* |
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* <p>The implementation takes equal advantage of ascending and |
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* descending order in its input array, and can take advantage of |
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* ascending and descending order in different parts of the same |
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* input array. It is well-suited to merging two or more sorted arrays: |
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* simply concatenate the arrays and sort the resulting array. |
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* |
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* <p>The implementation was adapted from Tim Peters's list sort for Python |
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* (<a href="http://svn.python.org/projects/python/trunk/Objects/listsort.txt"> |
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* TimSort</a>). It uses techiques from Peter McIlroy's "Optimistic |
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* Sorting and Information Theoretic Complexity", in Proceedings of the |
195 |
* Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, pp 467-474, |
196 |
* January 1993. |
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* |
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* <p>This implementation dumps the specified list into an array, sorts |
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* the array, and iterates over the list resetting each element |
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* from the corresponding position in the array. This avoids the |
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* n<sup>2</sup> log(n) performance that would result from attempting |
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* to sort a linked list in place. |
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* |
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* @param list the list to be sorted. |
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* @param c the comparator to determine the order of the list. A |
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* {@code null} value indicates that the elements' <i>natural |
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* ordering</i> should be used. |
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* @throws ClassCastException if the list contains elements that are not |
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* <i>mutually comparable</i> using the specified comparator. |
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* @throws UnsupportedOperationException if the specified list's |
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* list-iterator does not support the {@code set} operation. |
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* @throws IllegalArgumentException (optional) if the comparator is |
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* found to violate the {@link Comparator} contract |
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*/ |
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public static <T> void sort(List<T> list, Comparator<? super T> c) { |
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Object[] a = list.toArray(); |
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Arrays.sort(a, (Comparator)c); |
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ListIterator i = list.listIterator(); |
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for (int j=0; j<a.length; j++) { |
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i.next(); |
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i.set(a[j]); |
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} |
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} |
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|
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|
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/** |
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* Searches the specified list for the specified object using the binary |
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* search algorithm. The list must be sorted into ascending order |
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* according to the {@linkplain Comparable natural ordering} of its |
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* elements (as by the {@link #sort(List)} method) prior to making this |
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* call. If it is not sorted, the results are undefined. If the list |
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* contains multiple elements equal to the specified object, there is no |
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* guarantee which one will be found. |
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* |
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* <p>This method runs in log(n) time for a "random access" list (which |
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* provides near-constant-time positional access). If the specified list |
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* does not implement the {@link RandomAccess} interface and is large, |
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* this method will do an iterator-based binary search that performs |
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* O(n) link traversals and O(log n) element comparisons. |
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* |
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* @param list the list to be searched. |
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* @param key the key to be searched for. |
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* @return the index of the search key, if it is contained in the list; |
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* otherwise, <tt>(-(<i>insertion point</i>) - 1)</tt>. The |
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* <i>insertion point</i> is defined as the point at which the |
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* key would be inserted into the list: the index of the first |
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* element greater than the key, or <tt>list.size()</tt> if all |
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* elements in the list are less than the specified key. Note |
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* that this guarantees that the return value will be >= 0 if |
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* and only if the key is found. |
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* @throws ClassCastException if the list contains elements that are not |
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* <i>mutually comparable</i> (for example, strings and |
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* integers), or the search key is not mutually comparable |
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* with the elements of the list. |
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*/ |
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public static <T> |
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int binarySearch(List<? extends Comparable<? super T>> list, T key) { |
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if (list instanceof RandomAccess || list.size()<BINARYSEARCH_THRESHOLD) |
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return Collections.indexedBinarySearch(list, key); |
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else |
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return Collections.iteratorBinarySearch(list, key); |
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} |
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|
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private static <T> |
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int indexedBinarySearch(List<? extends Comparable<? super T>> list, T key) |
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{ |
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int low = 0; |
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int high = list.size()-1; |
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|
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while (low <= high) { |
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int mid = (low + high) >>> 1; |
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Comparable<? super T> midVal = list.get(mid); |
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int cmp = midVal.compareTo(key); |
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|
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if (cmp < 0) |
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low = mid + 1; |
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else if (cmp > 0) |
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high = mid - 1; |
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else |
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return mid; // key found |
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} |
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return -(low + 1); // key not found |
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} |
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|
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private static <T> |
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int iteratorBinarySearch(List<? extends Comparable<? super T>> list, T key) |
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{ |
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int low = 0; |
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int high = list.size()-1; |
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ListIterator<? extends Comparable<? super T>> i = list.listIterator(); |
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|
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while (low <= high) { |
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int mid = (low + high) >>> 1; |
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Comparable<? super T> midVal = get(i, mid); |
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int cmp = midVal.compareTo(key); |
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|
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if (cmp < 0) |
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low = mid + 1; |
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else if (cmp > 0) |
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high = mid - 1; |
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else |
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return mid; // key found |
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} |
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return -(low + 1); // key not found |
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} |
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|
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/** |
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* Gets the ith element from the given list by repositioning the specified |
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* list listIterator. |
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*/ |
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private static <T> T get(ListIterator<? extends T> i, int index) { |
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T obj = null; |
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int pos = i.nextIndex(); |
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if (pos <= index) { |
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do { |
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obj = i.next(); |
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} while (pos++ < index); |
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} else { |
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do { |
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obj = i.previous(); |
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} while (--pos > index); |
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} |
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return obj; |
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} |
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|
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/** |
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* Searches the specified list for the specified object using the binary |
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* search algorithm. The list must be sorted into ascending order |
329 |
* according to the specified comparator (as by the |
330 |
* {@link #sort(List, Comparator) sort(List, Comparator)} |
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* method), prior to making this call. If it is |
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* not sorted, the results are undefined. If the list contains multiple |
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* elements equal to the specified object, there is no guarantee which one |
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* will be found. |
335 |
* |
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* <p>This method runs in log(n) time for a "random access" list (which |
337 |
* provides near-constant-time positional access). If the specified list |
338 |
* does not implement the {@link RandomAccess} interface and is large, |
339 |
* this method will do an iterator-based binary search that performs |
340 |
* O(n) link traversals and O(log n) element comparisons. |
341 |
* |
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* @param list the list to be searched. |
343 |
* @param key the key to be searched for. |
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* @param c the comparator by which the list is ordered. |
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* A <tt>null</tt> value indicates that the elements' |
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* {@linkplain Comparable natural ordering} should be used. |
347 |
* @return the index of the search key, if it is contained in the list; |
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* otherwise, <tt>(-(<i>insertion point</i>) - 1)</tt>. The |
349 |
* <i>insertion point</i> is defined as the point at which the |
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* key would be inserted into the list: the index of the first |
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* element greater than the key, or <tt>list.size()</tt> if all |
352 |
* elements in the list are less than the specified key. Note |
353 |
* that this guarantees that the return value will be >= 0 if |
354 |
* and only if the key is found. |
355 |
* @throws ClassCastException if the list contains elements that are not |
356 |
* <i>mutually comparable</i> using the specified comparator, |
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* or the search key is not mutually comparable with the |
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* elements of the list using this comparator. |
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*/ |
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public static <T> int binarySearch(List<? extends T> list, T key, Comparator<? super T> c) { |
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if (c==null) |
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return binarySearch((List) list, key); |
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|
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if (list instanceof RandomAccess || list.size()<BINARYSEARCH_THRESHOLD) |
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return Collections.indexedBinarySearch(list, key, c); |
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else |
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return Collections.iteratorBinarySearch(list, key, c); |
368 |
} |
369 |
|
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private static <T> int indexedBinarySearch(List<? extends T> l, T key, Comparator<? super T> c) { |
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int low = 0; |
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int high = l.size()-1; |
373 |
|
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while (low <= high) { |
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int mid = (low + high) >>> 1; |
376 |
T midVal = l.get(mid); |
377 |
int cmp = c.compare(midVal, key); |
378 |
|
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if (cmp < 0) |
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low = mid + 1; |
381 |
else if (cmp > 0) |
382 |
high = mid - 1; |
383 |
else |
384 |
return mid; // key found |
385 |
} |
386 |
return -(low + 1); // key not found |
387 |
} |
388 |
|
389 |
private static <T> int iteratorBinarySearch(List<? extends T> l, T key, Comparator<? super T> c) { |
390 |
int low = 0; |
391 |
int high = l.size()-1; |
392 |
ListIterator<? extends T> i = l.listIterator(); |
393 |
|
394 |
while (low <= high) { |
395 |
int mid = (low + high) >>> 1; |
396 |
T midVal = get(i, mid); |
397 |
int cmp = c.compare(midVal, key); |
398 |
|
399 |
if (cmp < 0) |
400 |
low = mid + 1; |
401 |
else if (cmp > 0) |
402 |
high = mid - 1; |
403 |
else |
404 |
return mid; // key found |
405 |
} |
406 |
return -(low + 1); // key not found |
407 |
} |
408 |
|
409 |
private interface SelfComparable extends Comparable<SelfComparable> {} |
410 |
|
411 |
|
412 |
/** |
413 |
* Reverses the order of the elements in the specified list.<p> |
414 |
* |
415 |
* This method runs in linear time. |
416 |
* |
417 |
* @param list the list whose elements are to be reversed. |
418 |
* @throws UnsupportedOperationException if the specified list or |
419 |
* its list-iterator does not support the <tt>set</tt> operation. |
420 |
*/ |
421 |
public static void reverse(List<?> list) { |
422 |
int size = list.size(); |
423 |
if (size < REVERSE_THRESHOLD || list instanceof RandomAccess) { |
424 |
for (int i=0, mid=size>>1, j=size-1; i<mid; i++, j--) |
425 |
swap(list, i, j); |
426 |
} else { |
427 |
ListIterator fwd = list.listIterator(); |
428 |
ListIterator rev = list.listIterator(size); |
429 |
for (int i=0, mid=list.size()>>1; i<mid; i++) { |
430 |
Object tmp = fwd.next(); |
431 |
fwd.set(rev.previous()); |
432 |
rev.set(tmp); |
433 |
} |
434 |
} |
435 |
} |
436 |
|
437 |
/** |
438 |
* Randomly permutes the specified list using a default source of |
439 |
* randomness. All permutations occur with approximately equal |
440 |
* likelihood.<p> |
441 |
* |
442 |
* The hedge "approximately" is used in the foregoing description because |
443 |
* default source of randomness is only approximately an unbiased source |
444 |
* of independently chosen bits. If it were a perfect source of randomly |
445 |
* chosen bits, then the algorithm would choose permutations with perfect |
446 |
* uniformity.<p> |
447 |
* |
448 |
* This implementation traverses the list backwards, from the last element |
449 |
* up to the second, repeatedly swapping a randomly selected element into |
450 |
* the "current position". Elements are randomly selected from the |
451 |
* portion of the list that runs from the first element to the current |
452 |
* position, inclusive.<p> |
453 |
* |
454 |
* This method runs in linear time. If the specified list does not |
455 |
* implement the {@link RandomAccess} interface and is large, this |
456 |
* implementation dumps the specified list into an array before shuffling |
457 |
* it, and dumps the shuffled array back into the list. This avoids the |
458 |
* quadratic behavior that would result from shuffling a "sequential |
459 |
* access" list in place. |
460 |
* |
461 |
* @param list the list to be shuffled. |
462 |
* @throws UnsupportedOperationException if the specified list or |
463 |
* its list-iterator does not support the <tt>set</tt> operation. |
464 |
*/ |
465 |
public static void shuffle(List<?> list) { |
466 |
if (r == null) { |
467 |
r = new Random(); |
468 |
} |
469 |
shuffle(list, r); |
470 |
} |
471 |
private static Random r; |
472 |
|
473 |
/** |
474 |
* Randomly permute the specified list using the specified source of |
475 |
* randomness. All permutations occur with equal likelihood |
476 |
* assuming that the source of randomness is fair.<p> |
477 |
* |
478 |
* This implementation traverses the list backwards, from the last element |
479 |
* up to the second, repeatedly swapping a randomly selected element into |
480 |
* the "current position". Elements are randomly selected from the |
481 |
* portion of the list that runs from the first element to the current |
482 |
* position, inclusive.<p> |
483 |
* |
484 |
* This method runs in linear time. If the specified list does not |
485 |
* implement the {@link RandomAccess} interface and is large, this |
486 |
* implementation dumps the specified list into an array before shuffling |
487 |
* it, and dumps the shuffled array back into the list. This avoids the |
488 |
* quadratic behavior that would result from shuffling a "sequential |
489 |
* access" list in place. |
490 |
* |
491 |
* @param list the list to be shuffled. |
492 |
* @param rnd the source of randomness to use to shuffle the list. |
493 |
* @throws UnsupportedOperationException if the specified list or its |
494 |
* list-iterator does not support the <tt>set</tt> operation. |
495 |
*/ |
496 |
public static void shuffle(List<?> list, Random rnd) { |
497 |
int size = list.size(); |
498 |
if (size < SHUFFLE_THRESHOLD || list instanceof RandomAccess) { |
499 |
for (int i=size; i>1; i--) |
500 |
swap(list, i-1, rnd.nextInt(i)); |
501 |
} else { |
502 |
Object arr[] = list.toArray(); |
503 |
|
504 |
// Shuffle array |
505 |
for (int i=size; i>1; i--) |
506 |
swap(arr, i-1, rnd.nextInt(i)); |
507 |
|
508 |
// Dump array back into list |
509 |
ListIterator it = list.listIterator(); |
510 |
for (int i=0; i<arr.length; i++) { |
511 |
it.next(); |
512 |
it.set(arr[i]); |
513 |
} |
514 |
} |
515 |
} |
516 |
|
517 |
/** |
518 |
* Swaps the elements at the specified positions in the specified list. |
519 |
* (If the specified positions are equal, invoking this method leaves |
520 |
* the list unchanged.) |
521 |
* |
522 |
* @param list The list in which to swap elements. |
523 |
* @param i the index of one element to be swapped. |
524 |
* @param j the index of the other element to be swapped. |
525 |
* @throws IndexOutOfBoundsException if either <tt>i</tt> or <tt>j</tt> |
526 |
* is out of range (i < 0 || i >= list.size() |
527 |
* || j < 0 || j >= list.size()). |
528 |
* @since 1.4 |
529 |
*/ |
530 |
public static void swap(List<?> list, int i, int j) { |
531 |
final List l = list; |
532 |
l.set(i, l.set(j, l.get(i))); |
533 |
} |
534 |
|
535 |
/** |
536 |
* Swaps the two specified elements in the specified array. |
537 |
*/ |
538 |
private static void swap(Object[] arr, int i, int j) { |
539 |
Object tmp = arr[i]; |
540 |
arr[i] = arr[j]; |
541 |
arr[j] = tmp; |
542 |
} |
543 |
|
544 |
/** |
545 |
* Replaces all of the elements of the specified list with the specified |
546 |
* element. <p> |
547 |
* |
548 |
* This method runs in linear time. |
549 |
* |
550 |
* @param list the list to be filled with the specified element. |
551 |
* @param obj The element with which to fill the specified list. |
552 |
* @throws UnsupportedOperationException if the specified list or its |
553 |
* list-iterator does not support the <tt>set</tt> operation. |
554 |
*/ |
555 |
public static <T> void fill(List<? super T> list, T obj) { |
556 |
int size = list.size(); |
557 |
|
558 |
if (size < FILL_THRESHOLD || list instanceof RandomAccess) { |
559 |
for (int i=0; i<size; i++) |
560 |
list.set(i, obj); |
561 |
} else { |
562 |
ListIterator<? super T> itr = list.listIterator(); |
563 |
for (int i=0; i<size; i++) { |
564 |
itr.next(); |
565 |
itr.set(obj); |
566 |
} |
567 |
} |
568 |
} |
569 |
|
570 |
/** |
571 |
* Copies all of the elements from one list into another. After the |
572 |
* operation, the index of each copied element in the destination list |
573 |
* will be identical to its index in the source list. The destination |
574 |
* list must be at least as long as the source list. If it is longer, the |
575 |
* remaining elements in the destination list are unaffected. <p> |
576 |
* |
577 |
* This method runs in linear time. |
578 |
* |
579 |
* @param dest The destination list. |
580 |
* @param src The source list. |
581 |
* @throws IndexOutOfBoundsException if the destination list is too small |
582 |
* to contain the entire source List. |
583 |
* @throws UnsupportedOperationException if the destination list's |
584 |
* list-iterator does not support the <tt>set</tt> operation. |
585 |
*/ |
586 |
public static <T> void copy(List<? super T> dest, List<? extends T> src) { |
587 |
int srcSize = src.size(); |
588 |
if (srcSize > dest.size()) |
589 |
throw new IndexOutOfBoundsException("Source does not fit in dest"); |
590 |
|
591 |
if (srcSize < COPY_THRESHOLD || |
592 |
(src instanceof RandomAccess && dest instanceof RandomAccess)) { |
593 |
for (int i=0; i<srcSize; i++) |
594 |
dest.set(i, src.get(i)); |
595 |
} else { |
596 |
ListIterator<? super T> di=dest.listIterator(); |
597 |
ListIterator<? extends T> si=src.listIterator(); |
598 |
for (int i=0; i<srcSize; i++) { |
599 |
di.next(); |
600 |
di.set(si.next()); |
601 |
} |
602 |
} |
603 |
} |
604 |
|
605 |
/** |
606 |
* Returns the minimum element of the given collection, according to the |
607 |
* <i>natural ordering</i> of its elements. All elements in the |
608 |
* collection must implement the <tt>Comparable</tt> interface. |
609 |
* Furthermore, all elements in the collection must be <i>mutually |
610 |
* comparable</i> (that is, <tt>e1.compareTo(e2)</tt> must not throw a |
611 |
* <tt>ClassCastException</tt> for any elements <tt>e1</tt> and |
612 |
* <tt>e2</tt> in the collection).<p> |
613 |
* |
614 |
* This method iterates over the entire collection, hence it requires |
615 |
* time proportional to the size of the collection. |
616 |
* |
617 |
* @param coll the collection whose minimum element is to be determined. |
618 |
* @return the minimum element of the given collection, according |
619 |
* to the <i>natural ordering</i> of its elements. |
620 |
* @throws ClassCastException if the collection contains elements that are |
621 |
* not <i>mutually comparable</i> (for example, strings and |
622 |
* integers). |
623 |
* @throws NoSuchElementException if the collection is empty. |
624 |
* @see Comparable |
625 |
*/ |
626 |
public static <T extends Object & Comparable<? super T>> T min(Collection<? extends T> coll) { |
627 |
Iterator<? extends T> i = coll.iterator(); |
628 |
T candidate = i.next(); |
629 |
|
630 |
while (i.hasNext()) { |
631 |
T next = i.next(); |
632 |
if (next.compareTo(candidate) < 0) |
633 |
candidate = next; |
634 |
} |
635 |
return candidate; |
636 |
} |
637 |
|
638 |
/** |
639 |
* Returns the minimum element of the given collection, according to the |
640 |
* order induced by the specified comparator. All elements in the |
641 |
* collection must be <i>mutually comparable</i> by the specified |
642 |
* comparator (that is, <tt>comp.compare(e1, e2)</tt> must not throw a |
643 |
* <tt>ClassCastException</tt> for any elements <tt>e1</tt> and |
644 |
* <tt>e2</tt> in the collection).<p> |
645 |
* |
646 |
* This method iterates over the entire collection, hence it requires |
647 |
* time proportional to the size of the collection. |
648 |
* |
649 |
* @param coll the collection whose minimum element is to be determined. |
650 |
* @param comp the comparator with which to determine the minimum element. |
651 |
* A <tt>null</tt> value indicates that the elements' <i>natural |
652 |
* ordering</i> should be used. |
653 |
* @return the minimum element of the given collection, according |
654 |
* to the specified comparator. |
655 |
* @throws ClassCastException if the collection contains elements that are |
656 |
* not <i>mutually comparable</i> using the specified comparator. |
657 |
* @throws NoSuchElementException if the collection is empty. |
658 |
* @see Comparable |
659 |
*/ |
660 |
public static <T> T min(Collection<? extends T> coll, Comparator<? super T> comp) { |
661 |
if (comp==null) |
662 |
return (T)min((Collection<SelfComparable>) (Collection) coll); |
663 |
|
664 |
Iterator<? extends T> i = coll.iterator(); |
665 |
T candidate = i.next(); |
666 |
|
667 |
while (i.hasNext()) { |
668 |
T next = i.next(); |
669 |
if (comp.compare(next, candidate) < 0) |
670 |
candidate = next; |
671 |
} |
672 |
return candidate; |
673 |
} |
674 |
|
675 |
/** |
676 |
* Returns the maximum element of the given collection, according to the |
677 |
* <i>natural ordering</i> of its elements. All elements in the |
678 |
* collection must implement the <tt>Comparable</tt> interface. |
679 |
* Furthermore, all elements in the collection must be <i>mutually |
680 |
* comparable</i> (that is, <tt>e1.compareTo(e2)</tt> must not throw a |
681 |
* <tt>ClassCastException</tt> for any elements <tt>e1</tt> and |
682 |
* <tt>e2</tt> in the collection).<p> |
683 |
* |
684 |
* This method iterates over the entire collection, hence it requires |
685 |
* time proportional to the size of the collection. |
686 |
* |
687 |
* @param coll the collection whose maximum element is to be determined. |
688 |
* @return the maximum element of the given collection, according |
689 |
* to the <i>natural ordering</i> of its elements. |
690 |
* @throws ClassCastException if the collection contains elements that are |
691 |
* not <i>mutually comparable</i> (for example, strings and |
692 |
* integers). |
693 |
* @throws NoSuchElementException if the collection is empty. |
694 |
* @see Comparable |
695 |
*/ |
696 |
public static <T extends Object & Comparable<? super T>> T max(Collection<? extends T> coll) { |
697 |
Iterator<? extends T> i = coll.iterator(); |
698 |
T candidate = i.next(); |
699 |
|
700 |
while (i.hasNext()) { |
701 |
T next = i.next(); |
702 |
if (next.compareTo(candidate) > 0) |
703 |
candidate = next; |
704 |
} |
705 |
return candidate; |
706 |
} |
707 |
|
708 |
/** |
709 |
* Returns the maximum element of the given collection, according to the |
710 |
* order induced by the specified comparator. All elements in the |
711 |
* collection must be <i>mutually comparable</i> by the specified |
712 |
* comparator (that is, <tt>comp.compare(e1, e2)</tt> must not throw a |
713 |
* <tt>ClassCastException</tt> for any elements <tt>e1</tt> and |
714 |
* <tt>e2</tt> in the collection).<p> |
715 |
* |
716 |
* This method iterates over the entire collection, hence it requires |
717 |
* time proportional to the size of the collection. |
718 |
* |
719 |
* @param coll the collection whose maximum element is to be determined. |
720 |
* @param comp the comparator with which to determine the maximum element. |
721 |
* A <tt>null</tt> value indicates that the elements' <i>natural |
722 |
* ordering</i> should be used. |
723 |
* @return the maximum element of the given collection, according |
724 |
* to the specified comparator. |
725 |
* @throws ClassCastException if the collection contains elements that are |
726 |
* not <i>mutually comparable</i> using the specified comparator. |
727 |
* @throws NoSuchElementException if the collection is empty. |
728 |
* @see Comparable |
729 |
*/ |
730 |
public static <T> T max(Collection<? extends T> coll, Comparator<? super T> comp) { |
731 |
if (comp==null) |
732 |
return (T)max((Collection<SelfComparable>) (Collection) coll); |
733 |
|
734 |
Iterator<? extends T> i = coll.iterator(); |
735 |
T candidate = i.next(); |
736 |
|
737 |
while (i.hasNext()) { |
738 |
T next = i.next(); |
739 |
if (comp.compare(next, candidate) > 0) |
740 |
candidate = next; |
741 |
} |
742 |
return candidate; |
743 |
} |
744 |
|
745 |
/** |
746 |
* Rotates the elements in the specified list by the specified distance. |
747 |
* After calling this method, the element at index <tt>i</tt> will be |
748 |
* the element previously at index <tt>(i - distance)</tt> mod |
749 |
* <tt>list.size()</tt>, for all values of <tt>i</tt> between <tt>0</tt> |
750 |
* and <tt>list.size()-1</tt>, inclusive. (This method has no effect on |
751 |
* the size of the list.) |
752 |
* |
753 |
* <p>For example, suppose <tt>list</tt> comprises<tt> [t, a, n, k, s]</tt>. |
754 |
* After invoking <tt>Collections.rotate(list, 1)</tt> (or |
755 |
* <tt>Collections.rotate(list, -4)</tt>), <tt>list</tt> will comprise |
756 |
* <tt>[s, t, a, n, k]</tt>. |
757 |
* |
758 |
* <p>Note that this method can usefully be applied to sublists to |
759 |
* move one or more elements within a list while preserving the |
760 |
* order of the remaining elements. For example, the following idiom |
761 |
* moves the element at index <tt>j</tt> forward to position |
762 |
* <tt>k</tt> (which must be greater than or equal to <tt>j</tt>): |
763 |
* <pre> |
764 |
* Collections.rotate(list.subList(j, k+1), -1); |
765 |
* </pre> |
766 |
* To make this concrete, suppose <tt>list</tt> comprises |
767 |
* <tt>[a, b, c, d, e]</tt>. To move the element at index <tt>1</tt> |
768 |
* (<tt>b</tt>) forward two positions, perform the following invocation: |
769 |
* <pre> |
770 |
* Collections.rotate(l.subList(1, 4), -1); |
771 |
* </pre> |
772 |
* The resulting list is <tt>[a, c, d, b, e]</tt>. |
773 |
* |
774 |
* <p>To move more than one element forward, increase the absolute value |
775 |
* of the rotation distance. To move elements backward, use a positive |
776 |
* shift distance. |
777 |
* |
778 |
* <p>If the specified list is small or implements the {@link |
779 |
* RandomAccess} interface, this implementation exchanges the first |
780 |
* element into the location it should go, and then repeatedly exchanges |
781 |
* the displaced element into the location it should go until a displaced |
782 |
* element is swapped into the first element. If necessary, the process |
783 |
* is repeated on the second and successive elements, until the rotation |
784 |
* is complete. If the specified list is large and doesn't implement the |
785 |
* <tt>RandomAccess</tt> interface, this implementation breaks the |
786 |
* list into two sublist views around index <tt>-distance mod size</tt>. |
787 |
* Then the {@link #reverse(List)} method is invoked on each sublist view, |
788 |
* and finally it is invoked on the entire list. For a more complete |
789 |
* description of both algorithms, see Section 2.3 of Jon Bentley's |
790 |
* <i>Programming Pearls</i> (Addison-Wesley, 1986). |
791 |
* |
792 |
* @param list the list to be rotated. |
793 |
* @param distance the distance to rotate the list. There are no |
794 |
* constraints on this value; it may be zero, negative, or |
795 |
* greater than <tt>list.size()</tt>. |
796 |
* @throws UnsupportedOperationException if the specified list or |
797 |
* its list-iterator does not support the <tt>set</tt> operation. |
798 |
* @since 1.4 |
799 |
*/ |
800 |
public static void rotate(List<?> list, int distance) { |
801 |
if (list instanceof RandomAccess || list.size() < ROTATE_THRESHOLD) |
802 |
rotate1(list, distance); |
803 |
else |
804 |
rotate2(list, distance); |
805 |
} |
806 |
|
807 |
private static <T> void rotate1(List<T> list, int distance) { |
808 |
int size = list.size(); |
809 |
if (size == 0) |
810 |
return; |
811 |
distance = distance % size; |
812 |
if (distance < 0) |
813 |
distance += size; |
814 |
if (distance == 0) |
815 |
return; |
816 |
|
817 |
for (int cycleStart = 0, nMoved = 0; nMoved != size; cycleStart++) { |
818 |
T displaced = list.get(cycleStart); |
819 |
int i = cycleStart; |
820 |
do { |
821 |
i += distance; |
822 |
if (i >= size) |
823 |
i -= size; |
824 |
displaced = list.set(i, displaced); |
825 |
nMoved ++; |
826 |
} while (i != cycleStart); |
827 |
} |
828 |
} |
829 |
|
830 |
private static void rotate2(List<?> list, int distance) { |
831 |
int size = list.size(); |
832 |
if (size == 0) |
833 |
return; |
834 |
int mid = -distance % size; |
835 |
if (mid < 0) |
836 |
mid += size; |
837 |
if (mid == 0) |
838 |
return; |
839 |
|
840 |
reverse(list.subList(0, mid)); |
841 |
reverse(list.subList(mid, size)); |
842 |
reverse(list); |
843 |
} |
844 |
|
845 |
/** |
846 |
* Replaces all occurrences of one specified value in a list with another. |
847 |
* More formally, replaces with <tt>newVal</tt> each element <tt>e</tt> |
848 |
* in <tt>list</tt> such that |
849 |
* <tt>(oldVal==null ? e==null : oldVal.equals(e))</tt>. |
850 |
* (This method has no effect on the size of the list.) |
851 |
* |
852 |
* @param list the list in which replacement is to occur. |
853 |
* @param oldVal the old value to be replaced. |
854 |
* @param newVal the new value with which <tt>oldVal</tt> is to be |
855 |
* replaced. |
856 |
* @return <tt>true</tt> if <tt>list</tt> contained one or more elements |
857 |
* <tt>e</tt> such that |
858 |
* <tt>(oldVal==null ? e==null : oldVal.equals(e))</tt>. |
859 |
* @throws UnsupportedOperationException if the specified list or |
860 |
* its list-iterator does not support the <tt>set</tt> operation. |
861 |
* @since 1.4 |
862 |
*/ |
863 |
public static <T> boolean replaceAll(List<T> list, T oldVal, T newVal) { |
864 |
boolean result = false; |
865 |
int size = list.size(); |
866 |
if (size < REPLACEALL_THRESHOLD || list instanceof RandomAccess) { |
867 |
if (oldVal==null) { |
868 |
for (int i=0; i<size; i++) { |
869 |
if (list.get(i)==null) { |
870 |
list.set(i, newVal); |
871 |
result = true; |
872 |
} |
873 |
} |
874 |
} else { |
875 |
for (int i=0; i<size; i++) { |
876 |
if (oldVal.equals(list.get(i))) { |
877 |
list.set(i, newVal); |
878 |
result = true; |
879 |
} |
880 |
} |
881 |
} |
882 |
} else { |
883 |
ListIterator<T> itr=list.listIterator(); |
884 |
if (oldVal==null) { |
885 |
for (int i=0; i<size; i++) { |
886 |
if (itr.next()==null) { |
887 |
itr.set(newVal); |
888 |
result = true; |
889 |
} |
890 |
} |
891 |
} else { |
892 |
for (int i=0; i<size; i++) { |
893 |
if (oldVal.equals(itr.next())) { |
894 |
itr.set(newVal); |
895 |
result = true; |
896 |
} |
897 |
} |
898 |
} |
899 |
} |
900 |
return result; |
901 |
} |
902 |
|
903 |
/** |
904 |
* Returns the starting position of the first occurrence of the specified |
905 |
* target list within the specified source list, or -1 if there is no |
906 |
* such occurrence. More formally, returns the lowest index <tt>i</tt> |
907 |
* such that <tt>source.subList(i, i+target.size()).equals(target)</tt>, |
908 |
* or -1 if there is no such index. (Returns -1 if |
909 |
* <tt>target.size() > source.size()</tt>.) |
910 |
* |
911 |
* <p>This implementation uses the "brute force" technique of scanning |
912 |
* over the source list, looking for a match with the target at each |
913 |
* location in turn. |
914 |
* |
915 |
* @param source the list in which to search for the first occurrence |
916 |
* of <tt>target</tt>. |
917 |
* @param target the list to search for as a subList of <tt>source</tt>. |
918 |
* @return the starting position of the first occurrence of the specified |
919 |
* target list within the specified source list, or -1 if there |
920 |
* is no such occurrence. |
921 |
* @since 1.4 |
922 |
*/ |
923 |
public static int indexOfSubList(List<?> source, List<?> target) { |
924 |
int sourceSize = source.size(); |
925 |
int targetSize = target.size(); |
926 |
int maxCandidate = sourceSize - targetSize; |
927 |
|
928 |
if (sourceSize < INDEXOFSUBLIST_THRESHOLD || |
929 |
(source instanceof RandomAccess&&target instanceof RandomAccess)) { |
930 |
nextCand: |
931 |
for (int candidate = 0; candidate <= maxCandidate; candidate++) { |
932 |
for (int i=0, j=candidate; i<targetSize; i++, j++) |
933 |
if (!eq(target.get(i), source.get(j))) |
934 |
continue nextCand; // Element mismatch, try next cand |
935 |
return candidate; // All elements of candidate matched target |
936 |
} |
937 |
} else { // Iterator version of above algorithm |
938 |
ListIterator<?> si = source.listIterator(); |
939 |
nextCand: |
940 |
for (int candidate = 0; candidate <= maxCandidate; candidate++) { |
941 |
ListIterator<?> ti = target.listIterator(); |
942 |
for (int i=0; i<targetSize; i++) { |
943 |
if (!eq(ti.next(), si.next())) { |
944 |
// Back up source iterator to next candidate |
945 |
for (int j=0; j<i; j++) |
946 |
si.previous(); |
947 |
continue nextCand; |
948 |
} |
949 |
} |
950 |
return candidate; |
951 |
} |
952 |
} |
953 |
return -1; // No candidate matched the target |
954 |
} |
955 |
|
956 |
/** |
957 |
* Returns the starting position of the last occurrence of the specified |
958 |
* target list within the specified source list, or -1 if there is no such |
959 |
* occurrence. More formally, returns the highest index <tt>i</tt> |
960 |
* such that <tt>source.subList(i, i+target.size()).equals(target)</tt>, |
961 |
* or -1 if there is no such index. (Returns -1 if |
962 |
* <tt>target.size() > source.size()</tt>.) |
963 |
* |
964 |
* <p>This implementation uses the "brute force" technique of iterating |
965 |
* over the source list, looking for a match with the target at each |
966 |
* location in turn. |
967 |
* |
968 |
* @param source the list in which to search for the last occurrence |
969 |
* of <tt>target</tt>. |
970 |
* @param target the list to search for as a subList of <tt>source</tt>. |
971 |
* @return the starting position of the last occurrence of the specified |
972 |
* target list within the specified source list, or -1 if there |
973 |
* is no such occurrence. |
974 |
* @since 1.4 |
975 |
*/ |
976 |
public static int lastIndexOfSubList(List<?> source, List<?> target) { |
977 |
int sourceSize = source.size(); |
978 |
int targetSize = target.size(); |
979 |
int maxCandidate = sourceSize - targetSize; |
980 |
|
981 |
if (sourceSize < INDEXOFSUBLIST_THRESHOLD || |
982 |
source instanceof RandomAccess) { // Index access version |
983 |
nextCand: |
984 |
for (int candidate = maxCandidate; candidate >= 0; candidate--) { |
985 |
for (int i=0, j=candidate; i<targetSize; i++, j++) |
986 |
if (!eq(target.get(i), source.get(j))) |
987 |
continue nextCand; // Element mismatch, try next cand |
988 |
return candidate; // All elements of candidate matched target |
989 |
} |
990 |
} else { // Iterator version of above algorithm |
991 |
if (maxCandidate < 0) |
992 |
return -1; |
993 |
ListIterator<?> si = source.listIterator(maxCandidate); |
994 |
nextCand: |
995 |
for (int candidate = maxCandidate; candidate >= 0; candidate--) { |
996 |
ListIterator<?> ti = target.listIterator(); |
997 |
for (int i=0; i<targetSize; i++) { |
998 |
if (!eq(ti.next(), si.next())) { |
999 |
if (candidate != 0) { |
1000 |
// Back up source iterator to next candidate |
1001 |
for (int j=0; j<=i+1; j++) |
1002 |
si.previous(); |
1003 |
} |
1004 |
continue nextCand; |
1005 |
} |
1006 |
} |
1007 |
return candidate; |
1008 |
} |
1009 |
} |
1010 |
return -1; // No candidate matched the target |
1011 |
} |
1012 |
|
1013 |
|
1014 |
// Unmodifiable Wrappers |
1015 |
|
1016 |
/** |
1017 |
* Returns an unmodifiable view of the specified collection. This method |
1018 |
* allows modules to provide users with "read-only" access to internal |
1019 |
* collections. Query operations on the returned collection "read through" |
1020 |
* to the specified collection, and attempts to modify the returned |
1021 |
* collection, whether direct or via its iterator, result in an |
1022 |
* <tt>UnsupportedOperationException</tt>.<p> |
1023 |
* |
1024 |
* The returned collection does <i>not</i> pass the hashCode and equals |
1025 |
* operations through to the backing collection, but relies on |
1026 |
* <tt>Object</tt>'s <tt>equals</tt> and <tt>hashCode</tt> methods. This |
1027 |
* is necessary to preserve the contracts of these operations in the case |
1028 |
* that the backing collection is a set or a list.<p> |
1029 |
* |
1030 |
* The returned collection will be serializable if the specified collection |
1031 |
* is serializable. |
1032 |
* |
1033 |
* @param c the collection for which an unmodifiable view is to be |
1034 |
* returned. |
1035 |
* @return an unmodifiable view of the specified collection. |
1036 |
*/ |
1037 |
public static <T> Collection<T> unmodifiableCollection(Collection<? extends T> c) { |
1038 |
return new UnmodifiableCollection<T>(c); |
1039 |
} |
1040 |
|
1041 |
/** |
1042 |
* @serial include |
1043 |
*/ |
1044 |
static class UnmodifiableCollection<E> implements Collection<E>, Serializable { |
1045 |
private static final long serialVersionUID = 1820017752578914078L; |
1046 |
|
1047 |
final Collection<? extends E> c; |
1048 |
|
1049 |
UnmodifiableCollection(Collection<? extends E> c) { |
1050 |
if (c==null) |
1051 |
throw new NullPointerException(); |
1052 |
this.c = c; |
1053 |
} |
1054 |
|
1055 |
public int size() {return c.size();} |
1056 |
public boolean isEmpty() {return c.isEmpty();} |
1057 |
public boolean contains(Object o) {return c.contains(o);} |
1058 |
public Object[] toArray() {return c.toArray();} |
1059 |
public <T> T[] toArray(T[] a) {return c.toArray(a);} |
1060 |
public String toString() {return c.toString();} |
1061 |
|
1062 |
public Iterator<E> iterator() { |
1063 |
return new Iterator<E>() { |
1064 |
private final Iterator<? extends E> i = c.iterator(); |
1065 |
|
1066 |
public boolean hasNext() {return i.hasNext();} |
1067 |
public E next() {return i.next();} |
1068 |
public void remove() { |
1069 |
throw new UnsupportedOperationException(); |
1070 |
} |
1071 |
}; |
1072 |
} |
1073 |
|
1074 |
public boolean add(E e) { |
1075 |
throw new UnsupportedOperationException(); |
1076 |
} |
1077 |
public boolean remove(Object o) { |
1078 |
throw new UnsupportedOperationException(); |
1079 |
} |
1080 |
|
1081 |
public boolean containsAll(Collection<?> coll) { |
1082 |
return c.containsAll(coll); |
1083 |
} |
1084 |
public boolean addAll(Collection<? extends E> coll) { |
1085 |
throw new UnsupportedOperationException(); |
1086 |
} |
1087 |
public boolean removeAll(Collection<?> coll) { |
1088 |
throw new UnsupportedOperationException(); |
1089 |
} |
1090 |
public boolean retainAll(Collection<?> coll) { |
1091 |
throw new UnsupportedOperationException(); |
1092 |
} |
1093 |
public void clear() { |
1094 |
throw new UnsupportedOperationException(); |
1095 |
} |
1096 |
} |
1097 |
|
1098 |
/** |
1099 |
* Returns an unmodifiable view of the specified set. This method allows |
1100 |
* modules to provide users with "read-only" access to internal sets. |
1101 |
* Query operations on the returned set "read through" to the specified |
1102 |
* set, and attempts to modify the returned set, whether direct or via its |
1103 |
* iterator, result in an <tt>UnsupportedOperationException</tt>.<p> |
1104 |
* |
1105 |
* The returned set will be serializable if the specified set |
1106 |
* is serializable. |
1107 |
* |
1108 |
* @param s the set for which an unmodifiable view is to be returned. |
1109 |
* @return an unmodifiable view of the specified set. |
1110 |
*/ |
1111 |
public static <T> Set<T> unmodifiableSet(Set<? extends T> s) { |
1112 |
return new UnmodifiableSet<T>(s); |
1113 |
} |
1114 |
|
1115 |
/** |
1116 |
* @serial include |
1117 |
*/ |
1118 |
static class UnmodifiableSet<E> extends UnmodifiableCollection<E> |
1119 |
implements Set<E>, Serializable { |
1120 |
private static final long serialVersionUID = -9215047833775013803L; |
1121 |
|
1122 |
UnmodifiableSet(Set<? extends E> s) {super(s);} |
1123 |
public boolean equals(Object o) {return o == this || c.equals(o);} |
1124 |
public int hashCode() {return c.hashCode();} |
1125 |
} |
1126 |
|
1127 |
/** |
1128 |
* Returns an unmodifiable view of the specified sorted set. This method |
1129 |
* allows modules to provide users with "read-only" access to internal |
1130 |
* sorted sets. Query operations on the returned sorted set "read |
1131 |
* through" to the specified sorted set. Attempts to modify the returned |
1132 |
* sorted set, whether direct, via its iterator, or via its |
1133 |
* <tt>subSet</tt>, <tt>headSet</tt>, or <tt>tailSet</tt> views, result in |
1134 |
* an <tt>UnsupportedOperationException</tt>.<p> |
1135 |
* |
1136 |
* The returned sorted set will be serializable if the specified sorted set |
1137 |
* is serializable. |
1138 |
* |
1139 |
* @param s the sorted set for which an unmodifiable view is to be |
1140 |
* returned. |
1141 |
* @return an unmodifiable view of the specified sorted set. |
1142 |
*/ |
1143 |
public static <T> SortedSet<T> unmodifiableSortedSet(SortedSet<T> s) { |
1144 |
return new UnmodifiableSortedSet<T>(s); |
1145 |
} |
1146 |
|
1147 |
/** |
1148 |
* @serial include |
1149 |
*/ |
1150 |
static class UnmodifiableSortedSet<E> |
1151 |
extends UnmodifiableSet<E> |
1152 |
implements SortedSet<E>, Serializable { |
1153 |
private static final long serialVersionUID = -4929149591599911165L; |
1154 |
private final SortedSet<E> ss; |
1155 |
|
1156 |
UnmodifiableSortedSet(SortedSet<E> s) {super(s); ss = s;} |
1157 |
|
1158 |
public Comparator<? super E> comparator() {return ss.comparator();} |
1159 |
|
1160 |
public SortedSet<E> subSet(E fromElement, E toElement) { |
1161 |
return new UnmodifiableSortedSet<E>(ss.subSet(fromElement,toElement)); |
1162 |
} |
1163 |
public SortedSet<E> headSet(E toElement) { |
1164 |
return new UnmodifiableSortedSet<E>(ss.headSet(toElement)); |
1165 |
} |
1166 |
public SortedSet<E> tailSet(E fromElement) { |
1167 |
return new UnmodifiableSortedSet<E>(ss.tailSet(fromElement)); |
1168 |
} |
1169 |
|
1170 |
public E first() {return ss.first();} |
1171 |
public E last() {return ss.last();} |
1172 |
} |
1173 |
|
1174 |
/** |
1175 |
* Returns an unmodifiable view of the specified list. This method allows |
1176 |
* modules to provide users with "read-only" access to internal |
1177 |
* lists. Query operations on the returned list "read through" to the |
1178 |
* specified list, and attempts to modify the returned list, whether |
1179 |
* direct or via its iterator, result in an |
1180 |
* <tt>UnsupportedOperationException</tt>.<p> |
1181 |
* |
1182 |
* The returned list will be serializable if the specified list |
1183 |
* is serializable. Similarly, the returned list will implement |
1184 |
* {@link RandomAccess} if the specified list does. |
1185 |
* |
1186 |
* @param list the list for which an unmodifiable view is to be returned. |
1187 |
* @return an unmodifiable view of the specified list. |
1188 |
*/ |
1189 |
public static <T> List<T> unmodifiableList(List<? extends T> list) { |
1190 |
return (list instanceof RandomAccess ? |
1191 |
new UnmodifiableRandomAccessList<T>(list) : |
1192 |
new UnmodifiableList<T>(list)); |
1193 |
} |
1194 |
|
1195 |
/** |
1196 |
* @serial include |
1197 |
*/ |
1198 |
static class UnmodifiableList<E> extends UnmodifiableCollection<E> |
1199 |
implements List<E> { |
1200 |
private static final long serialVersionUID = -283967356065247728L; |
1201 |
final List<? extends E> list; |
1202 |
|
1203 |
UnmodifiableList(List<? extends E> list) { |
1204 |
super(list); |
1205 |
this.list = list; |
1206 |
} |
1207 |
|
1208 |
public boolean equals(Object o) {return o == this || list.equals(o);} |
1209 |
public int hashCode() {return list.hashCode();} |
1210 |
|
1211 |
public E get(int index) {return list.get(index);} |
1212 |
public E set(int index, E element) { |
1213 |
throw new UnsupportedOperationException(); |
1214 |
} |
1215 |
public void add(int index, E element) { |
1216 |
throw new UnsupportedOperationException(); |
1217 |
} |
1218 |
public E remove(int index) { |
1219 |
throw new UnsupportedOperationException(); |
1220 |
} |
1221 |
public int indexOf(Object o) {return list.indexOf(o);} |
1222 |
public int lastIndexOf(Object o) {return list.lastIndexOf(o);} |
1223 |
public boolean addAll(int index, Collection<? extends E> c) { |
1224 |
throw new UnsupportedOperationException(); |
1225 |
} |
1226 |
public ListIterator<E> listIterator() {return listIterator(0);} |
1227 |
|
1228 |
public ListIterator<E> listIterator(final int index) { |
1229 |
return new ListIterator<E>() { |
1230 |
private final ListIterator<? extends E> i |
1231 |
= list.listIterator(index); |
1232 |
|
1233 |
public boolean hasNext() {return i.hasNext();} |
1234 |
public E next() {return i.next();} |
1235 |
public boolean hasPrevious() {return i.hasPrevious();} |
1236 |
public E previous() {return i.previous();} |
1237 |
public int nextIndex() {return i.nextIndex();} |
1238 |
public int previousIndex() {return i.previousIndex();} |
1239 |
|
1240 |
public void remove() { |
1241 |
throw new UnsupportedOperationException(); |
1242 |
} |
1243 |
public void set(E e) { |
1244 |
throw new UnsupportedOperationException(); |
1245 |
} |
1246 |
public void add(E e) { |
1247 |
throw new UnsupportedOperationException(); |
1248 |
} |
1249 |
}; |
1250 |
} |
1251 |
|
1252 |
public List<E> subList(int fromIndex, int toIndex) { |
1253 |
return new UnmodifiableList<E>(list.subList(fromIndex, toIndex)); |
1254 |
} |
1255 |
|
1256 |
/** |
1257 |
* UnmodifiableRandomAccessList instances are serialized as |
1258 |
* UnmodifiableList instances to allow them to be deserialized |
1259 |
* in pre-1.4 JREs (which do not have UnmodifiableRandomAccessList). |
1260 |
* This method inverts the transformation. As a beneficial |
1261 |
* side-effect, it also grafts the RandomAccess marker onto |
1262 |
* UnmodifiableList instances that were serialized in pre-1.4 JREs. |
1263 |
* |
1264 |
* Note: Unfortunately, UnmodifiableRandomAccessList instances |
1265 |
* serialized in 1.4.1 and deserialized in 1.4 will become |
1266 |
* UnmodifiableList instances, as this method was missing in 1.4. |
1267 |
*/ |
1268 |
private Object readResolve() { |
1269 |
return (list instanceof RandomAccess |
1270 |
? new UnmodifiableRandomAccessList<E>(list) |
1271 |
: this); |
1272 |
} |
1273 |
} |
1274 |
|
1275 |
/** |
1276 |
* @serial include |
1277 |
*/ |
1278 |
static class UnmodifiableRandomAccessList<E> extends UnmodifiableList<E> |
1279 |
implements RandomAccess |
1280 |
{ |
1281 |
UnmodifiableRandomAccessList(List<? extends E> list) { |
1282 |
super(list); |
1283 |
} |
1284 |
|
1285 |
public List<E> subList(int fromIndex, int toIndex) { |
1286 |
return new UnmodifiableRandomAccessList<E>( |
1287 |
list.subList(fromIndex, toIndex)); |
1288 |
} |
1289 |
|
1290 |
private static final long serialVersionUID = -2542308836966382001L; |
1291 |
|
1292 |
/** |
1293 |
* Allows instances to be deserialized in pre-1.4 JREs (which do |
1294 |
* not have UnmodifiableRandomAccessList). UnmodifiableList has |
1295 |
* a readResolve method that inverts this transformation upon |
1296 |
* deserialization. |
1297 |
*/ |
1298 |
private Object writeReplace() { |
1299 |
return new UnmodifiableList<E>(list); |
1300 |
} |
1301 |
} |
1302 |
|
1303 |
/** |
1304 |
* Returns an unmodifiable view of the specified map. This method |
1305 |
* allows modules to provide users with "read-only" access to internal |
1306 |
* maps. Query operations on the returned map "read through" |
1307 |
* to the specified map, and attempts to modify the returned |
1308 |
* map, whether direct or via its collection views, result in an |
1309 |
* <tt>UnsupportedOperationException</tt>.<p> |
1310 |
* |
1311 |
* The returned map will be serializable if the specified map |
1312 |
* is serializable. |
1313 |
* |
1314 |
* @param m the map for which an unmodifiable view is to be returned. |
1315 |
* @return an unmodifiable view of the specified map. |
1316 |
*/ |
1317 |
public static <K,V> Map<K,V> unmodifiableMap(Map<? extends K, ? extends V> m) { |
1318 |
return new UnmodifiableMap<K,V>(m); |
1319 |
} |
1320 |
|
1321 |
/** |
1322 |
* @serial include |
1323 |
*/ |
1324 |
private static class UnmodifiableMap<K,V> implements Map<K,V>, Serializable { |
1325 |
private static final long serialVersionUID = -1034234728574286014L; |
1326 |
|
1327 |
private final Map<? extends K, ? extends V> m; |
1328 |
|
1329 |
UnmodifiableMap(Map<? extends K, ? extends V> m) { |
1330 |
if (m==null) |
1331 |
throw new NullPointerException(); |
1332 |
this.m = m; |
1333 |
} |
1334 |
|
1335 |
public int size() {return m.size();} |
1336 |
public boolean isEmpty() {return m.isEmpty();} |
1337 |
public boolean containsKey(Object key) {return m.containsKey(key);} |
1338 |
public boolean containsValue(Object val) {return m.containsValue(val);} |
1339 |
public V get(Object key) {return m.get(key);} |
1340 |
|
1341 |
public V put(K key, V value) { |
1342 |
throw new UnsupportedOperationException(); |
1343 |
} |
1344 |
public V remove(Object key) { |
1345 |
throw new UnsupportedOperationException(); |
1346 |
} |
1347 |
public void putAll(Map<? extends K, ? extends V> m) { |
1348 |
throw new UnsupportedOperationException(); |
1349 |
} |
1350 |
public void clear() { |
1351 |
throw new UnsupportedOperationException(); |
1352 |
} |
1353 |
|
1354 |
private transient Set<K> keySet = null; |
1355 |
private transient Set<Map.Entry<K,V>> entrySet = null; |
1356 |
private transient Collection<V> values = null; |
1357 |
|
1358 |
public Set<K> keySet() { |
1359 |
if (keySet==null) |
1360 |
keySet = unmodifiableSet(m.keySet()); |
1361 |
return keySet; |
1362 |
} |
1363 |
|
1364 |
public Set<Map.Entry<K,V>> entrySet() { |
1365 |
if (entrySet==null) |
1366 |
entrySet = new UnmodifiableEntrySet<K,V>(m.entrySet()); |
1367 |
return entrySet; |
1368 |
} |
1369 |
|
1370 |
public Collection<V> values() { |
1371 |
if (values==null) |
1372 |
values = unmodifiableCollection(m.values()); |
1373 |
return values; |
1374 |
} |
1375 |
|
1376 |
public boolean equals(Object o) {return o == this || m.equals(o);} |
1377 |
public int hashCode() {return m.hashCode();} |
1378 |
public String toString() {return m.toString();} |
1379 |
|
1380 |
/** |
1381 |
* We need this class in addition to UnmodifiableSet as |
1382 |
* Map.Entries themselves permit modification of the backing Map |
1383 |
* via their setValue operation. This class is subtle: there are |
1384 |
* many possible attacks that must be thwarted. |
1385 |
* |
1386 |
* @serial include |
1387 |
*/ |
1388 |
static class UnmodifiableEntrySet<K,V> |
1389 |
extends UnmodifiableSet<Map.Entry<K,V>> { |
1390 |
private static final long serialVersionUID = 7854390611657943733L; |
1391 |
|
1392 |
UnmodifiableEntrySet(Set<? extends Map.Entry<? extends K, ? extends V>> s) { |
1393 |
super((Set)s); |
1394 |
} |
1395 |
public Iterator<Map.Entry<K,V>> iterator() { |
1396 |
return new Iterator<Map.Entry<K,V>>() { |
1397 |
private final Iterator<? extends Map.Entry<? extends K, ? extends V>> i = c.iterator(); |
1398 |
|
1399 |
public boolean hasNext() { |
1400 |
return i.hasNext(); |
1401 |
} |
1402 |
public Map.Entry<K,V> next() { |
1403 |
return new UnmodifiableEntry<K,V>(i.next()); |
1404 |
} |
1405 |
public void remove() { |
1406 |
throw new UnsupportedOperationException(); |
1407 |
} |
1408 |
}; |
1409 |
} |
1410 |
|
1411 |
public Object[] toArray() { |
1412 |
Object[] a = c.toArray(); |
1413 |
for (int i=0; i<a.length; i++) |
1414 |
a[i] = new UnmodifiableEntry<K,V>((Map.Entry<K,V>)a[i]); |
1415 |
return a; |
1416 |
} |
1417 |
|
1418 |
public <T> T[] toArray(T[] a) { |
1419 |
// We don't pass a to c.toArray, to avoid window of |
1420 |
// vulnerability wherein an unscrupulous multithreaded client |
1421 |
// could get his hands on raw (unwrapped) Entries from c. |
1422 |
Object[] arr = c.toArray(a.length==0 ? a : Arrays.copyOf(a, 0)); |
1423 |
|
1424 |
for (int i=0; i<arr.length; i++) |
1425 |
arr[i] = new UnmodifiableEntry<K,V>((Map.Entry<K,V>)arr[i]); |
1426 |
|
1427 |
if (arr.length > a.length) |
1428 |
return (T[])arr; |
1429 |
|
1430 |
System.arraycopy(arr, 0, a, 0, arr.length); |
1431 |
if (a.length > arr.length) |
1432 |
a[arr.length] = null; |
1433 |
return a; |
1434 |
} |
1435 |
|
1436 |
/** |
1437 |
* This method is overridden to protect the backing set against |
1438 |
* an object with a nefarious equals function that senses |
1439 |
* that the equality-candidate is Map.Entry and calls its |
1440 |
* setValue method. |
1441 |
*/ |
1442 |
public boolean contains(Object o) { |
1443 |
if (!(o instanceof Map.Entry)) |
1444 |
return false; |
1445 |
return c.contains( |
1446 |
new UnmodifiableEntry<Object,Object>((Map.Entry<?,?>) o)); |
1447 |
} |
1448 |
|
1449 |
/** |
1450 |
* The next two methods are overridden to protect against |
1451 |
* an unscrupulous List whose contains(Object o) method senses |
1452 |
* when o is a Map.Entry, and calls o.setValue. |
1453 |
*/ |
1454 |
public boolean containsAll(Collection<?> coll) { |
1455 |
for (Object e : coll) { |
1456 |
if (!contains(e)) // Invokes safe contains() above |
1457 |
return false; |
1458 |
} |
1459 |
return true; |
1460 |
} |
1461 |
public boolean equals(Object o) { |
1462 |
if (o == this) |
1463 |
return true; |
1464 |
|
1465 |
if (!(o instanceof Set)) |
1466 |
return false; |
1467 |
Set s = (Set) o; |
1468 |
if (s.size() != c.size()) |
1469 |
return false; |
1470 |
return containsAll(s); // Invokes safe containsAll() above |
1471 |
} |
1472 |
|
1473 |
/** |
1474 |
* This "wrapper class" serves two purposes: it prevents |
1475 |
* the client from modifying the backing Map, by short-circuiting |
1476 |
* the setValue method, and it protects the backing Map against |
1477 |
* an ill-behaved Map.Entry that attempts to modify another |
1478 |
* Map Entry when asked to perform an equality check. |
1479 |
*/ |
1480 |
private static class UnmodifiableEntry<K,V> implements Map.Entry<K,V> { |
1481 |
private Map.Entry<? extends K, ? extends V> e; |
1482 |
|
1483 |
UnmodifiableEntry(Map.Entry<? extends K, ? extends V> e) {this.e = e;} |
1484 |
|
1485 |
public K getKey() {return e.getKey();} |
1486 |
public V getValue() {return e.getValue();} |
1487 |
public V setValue(V value) { |
1488 |
throw new UnsupportedOperationException(); |
1489 |
} |
1490 |
public int hashCode() {return e.hashCode();} |
1491 |
public boolean equals(Object o) { |
1492 |
if (!(o instanceof Map.Entry)) |
1493 |
return false; |
1494 |
Map.Entry t = (Map.Entry)o; |
1495 |
return eq(e.getKey(), t.getKey()) && |
1496 |
eq(e.getValue(), t.getValue()); |
1497 |
} |
1498 |
public String toString() {return e.toString();} |
1499 |
} |
1500 |
} |
1501 |
} |
1502 |
|
1503 |
/** |
1504 |
* Returns an unmodifiable view of the specified sorted map. This method |
1505 |
* allows modules to provide users with "read-only" access to internal |
1506 |
* sorted maps. Query operations on the returned sorted map "read through" |
1507 |
* to the specified sorted map. Attempts to modify the returned |
1508 |
* sorted map, whether direct, via its collection views, or via its |
1509 |
* <tt>subMap</tt>, <tt>headMap</tt>, or <tt>tailMap</tt> views, result in |
1510 |
* an <tt>UnsupportedOperationException</tt>.<p> |
1511 |
* |
1512 |
* The returned sorted map will be serializable if the specified sorted map |
1513 |
* is serializable. |
1514 |
* |
1515 |
* @param m the sorted map for which an unmodifiable view is to be |
1516 |
* returned. |
1517 |
* @return an unmodifiable view of the specified sorted map. |
1518 |
*/ |
1519 |
public static <K,V> SortedMap<K,V> unmodifiableSortedMap(SortedMap<K, ? extends V> m) { |
1520 |
return new UnmodifiableSortedMap<K,V>(m); |
1521 |
} |
1522 |
|
1523 |
/** |
1524 |
* @serial include |
1525 |
*/ |
1526 |
static class UnmodifiableSortedMap<K,V> |
1527 |
extends UnmodifiableMap<K,V> |
1528 |
implements SortedMap<K,V>, Serializable { |
1529 |
private static final long serialVersionUID = -8806743815996713206L; |
1530 |
|
1531 |
private final SortedMap<K, ? extends V> sm; |
1532 |
|
1533 |
UnmodifiableSortedMap(SortedMap<K, ? extends V> m) {super(m); sm = m;} |
1534 |
|
1535 |
public Comparator<? super K> comparator() {return sm.comparator();} |
1536 |
|
1537 |
public SortedMap<K,V> subMap(K fromKey, K toKey) { |
1538 |
return new UnmodifiableSortedMap<K,V>(sm.subMap(fromKey, toKey)); |
1539 |
} |
1540 |
public SortedMap<K,V> headMap(K toKey) { |
1541 |
return new UnmodifiableSortedMap<K,V>(sm.headMap(toKey)); |
1542 |
} |
1543 |
public SortedMap<K,V> tailMap(K fromKey) { |
1544 |
return new UnmodifiableSortedMap<K,V>(sm.tailMap(fromKey)); |
1545 |
} |
1546 |
|
1547 |
public K firstKey() {return sm.firstKey();} |
1548 |
public K lastKey() {return sm.lastKey();} |
1549 |
} |
1550 |
|
1551 |
|
1552 |
// Synch Wrappers |
1553 |
|
1554 |
/** |
1555 |
* Returns a synchronized (thread-safe) collection backed by the specified |
1556 |
* collection. In order to guarantee serial access, it is critical that |
1557 |
* <strong>all</strong> access to the backing collection is accomplished |
1558 |
* through the returned collection.<p> |
1559 |
* |
1560 |
* It is imperative that the user manually synchronize on the returned |
1561 |
* collection when iterating over it: |
1562 |
* <pre> |
1563 |
* Collection c = Collections.synchronizedCollection(myCollection); |
1564 |
* ... |
1565 |
* synchronized (c) { |
1566 |
* Iterator i = c.iterator(); // Must be in the synchronized block |
1567 |
* while (i.hasNext()) |
1568 |
* foo(i.next()); |
1569 |
* } |
1570 |
* </pre> |
1571 |
* Failure to follow this advice may result in non-deterministic behavior. |
1572 |
* |
1573 |
* <p>The returned collection does <i>not</i> pass the <tt>hashCode</tt> |
1574 |
* and <tt>equals</tt> operations through to the backing collection, but |
1575 |
* relies on <tt>Object</tt>'s equals and hashCode methods. This is |
1576 |
* necessary to preserve the contracts of these operations in the case |
1577 |
* that the backing collection is a set or a list.<p> |
1578 |
* |
1579 |
* The returned collection will be serializable if the specified collection |
1580 |
* is serializable. |
1581 |
* |
1582 |
* @param c the collection to be "wrapped" in a synchronized collection. |
1583 |
* @return a synchronized view of the specified collection. |
1584 |
*/ |
1585 |
public static <T> Collection<T> synchronizedCollection(Collection<T> c) { |
1586 |
return new SynchronizedCollection<T>(c); |
1587 |
} |
1588 |
|
1589 |
static <T> Collection<T> synchronizedCollection(Collection<T> c, Object mutex) { |
1590 |
return new SynchronizedCollection<T>(c, mutex); |
1591 |
} |
1592 |
|
1593 |
/** |
1594 |
* @serial include |
1595 |
*/ |
1596 |
static class SynchronizedCollection<E> implements Collection<E>, Serializable { |
1597 |
private static final long serialVersionUID = 3053995032091335093L; |
1598 |
|
1599 |
final Collection<E> c; // Backing Collection |
1600 |
final Object mutex; // Object on which to synchronize |
1601 |
|
1602 |
SynchronizedCollection(Collection<E> c) { |
1603 |
if (c==null) |
1604 |
throw new NullPointerException(); |
1605 |
this.c = c; |
1606 |
mutex = this; |
1607 |
} |
1608 |
SynchronizedCollection(Collection<E> c, Object mutex) { |
1609 |
this.c = c; |
1610 |
this.mutex = mutex; |
1611 |
} |
1612 |
|
1613 |
public int size() { |
1614 |
synchronized (mutex) {return c.size();} |
1615 |
} |
1616 |
public boolean isEmpty() { |
1617 |
synchronized (mutex) {return c.isEmpty();} |
1618 |
} |
1619 |
public boolean contains(Object o) { |
1620 |
synchronized (mutex) {return c.contains(o);} |
1621 |
} |
1622 |
public Object[] toArray() { |
1623 |
synchronized (mutex) {return c.toArray();} |
1624 |
} |
1625 |
public <T> T[] toArray(T[] a) { |
1626 |
synchronized (mutex) {return c.toArray(a);} |
1627 |
} |
1628 |
|
1629 |
public Iterator<E> iterator() { |
1630 |
return c.iterator(); // Must be manually synched by user! |
1631 |
} |
1632 |
|
1633 |
public boolean add(E e) { |
1634 |
synchronized (mutex) {return c.add(e);} |
1635 |
} |
1636 |
public boolean remove(Object o) { |
1637 |
synchronized (mutex) {return c.remove(o);} |
1638 |
} |
1639 |
|
1640 |
public boolean containsAll(Collection<?> coll) { |
1641 |
synchronized (mutex) {return c.containsAll(coll);} |
1642 |
} |
1643 |
public boolean addAll(Collection<? extends E> coll) { |
1644 |
synchronized (mutex) {return c.addAll(coll);} |
1645 |
} |
1646 |
public boolean removeAll(Collection<?> coll) { |
1647 |
synchronized (mutex) {return c.removeAll(coll);} |
1648 |
} |
1649 |
public boolean retainAll(Collection<?> coll) { |
1650 |
synchronized (mutex) {return c.retainAll(coll);} |
1651 |
} |
1652 |
public void clear() { |
1653 |
synchronized (mutex) {c.clear();} |
1654 |
} |
1655 |
public String toString() { |
1656 |
synchronized (mutex) {return c.toString();} |
1657 |
} |
1658 |
private void writeObject(ObjectOutputStream s) throws IOException { |
1659 |
synchronized (mutex) {s.defaultWriteObject();} |
1660 |
} |
1661 |
} |
1662 |
|
1663 |
/** |
1664 |
* Returns a synchronized (thread-safe) set backed by the specified |
1665 |
* set. In order to guarantee serial access, it is critical that |
1666 |
* <strong>all</strong> access to the backing set is accomplished |
1667 |
* through the returned set.<p> |
1668 |
* |
1669 |
* It is imperative that the user manually synchronize on the returned |
1670 |
* set when iterating over it: |
1671 |
* <pre> |
1672 |
* Set s = Collections.synchronizedSet(new HashSet()); |
1673 |
* ... |
1674 |
* synchronized (s) { |
1675 |
* Iterator i = s.iterator(); // Must be in the synchronized block |
1676 |
* while (i.hasNext()) |
1677 |
* foo(i.next()); |
1678 |
* } |
1679 |
* </pre> |
1680 |
* Failure to follow this advice may result in non-deterministic behavior. |
1681 |
* |
1682 |
* <p>The returned set will be serializable if the specified set is |
1683 |
* serializable. |
1684 |
* |
1685 |
* @param s the set to be "wrapped" in a synchronized set. |
1686 |
* @return a synchronized view of the specified set. |
1687 |
*/ |
1688 |
public static <T> Set<T> synchronizedSet(Set<T> s) { |
1689 |
return new SynchronizedSet<T>(s); |
1690 |
} |
1691 |
|
1692 |
static <T> Set<T> synchronizedSet(Set<T> s, Object mutex) { |
1693 |
return new SynchronizedSet<T>(s, mutex); |
1694 |
} |
1695 |
|
1696 |
/** |
1697 |
* @serial include |
1698 |
*/ |
1699 |
static class SynchronizedSet<E> |
1700 |
extends SynchronizedCollection<E> |
1701 |
implements Set<E> { |
1702 |
private static final long serialVersionUID = 487447009682186044L; |
1703 |
|
1704 |
SynchronizedSet(Set<E> s) { |
1705 |
super(s); |
1706 |
} |
1707 |
SynchronizedSet(Set<E> s, Object mutex) { |
1708 |
super(s, mutex); |
1709 |
} |
1710 |
|
1711 |
public boolean equals(Object o) { |
1712 |
synchronized (mutex) {return c.equals(o);} |
1713 |
} |
1714 |
public int hashCode() { |
1715 |
synchronized (mutex) {return c.hashCode();} |
1716 |
} |
1717 |
} |
1718 |
|
1719 |
/** |
1720 |
* Returns a synchronized (thread-safe) sorted set backed by the specified |
1721 |
* sorted set. In order to guarantee serial access, it is critical that |
1722 |
* <strong>all</strong> access to the backing sorted set is accomplished |
1723 |
* through the returned sorted set (or its views).<p> |
1724 |
* |
1725 |
* It is imperative that the user manually synchronize on the returned |
1726 |
* sorted set when iterating over it or any of its <tt>subSet</tt>, |
1727 |
* <tt>headSet</tt>, or <tt>tailSet</tt> views. |
1728 |
* <pre> |
1729 |
* SortedSet s = Collections.synchronizedSortedSet(new TreeSet()); |
1730 |
* ... |
1731 |
* synchronized (s) { |
1732 |
* Iterator i = s.iterator(); // Must be in the synchronized block |
1733 |
* while (i.hasNext()) |
1734 |
* foo(i.next()); |
1735 |
* } |
1736 |
* </pre> |
1737 |
* or: |
1738 |
* <pre> |
1739 |
* SortedSet s = Collections.synchronizedSortedSet(new TreeSet()); |
1740 |
* SortedSet s2 = s.headSet(foo); |
1741 |
* ... |
1742 |
* synchronized (s) { // Note: s, not s2!!! |
1743 |
* Iterator i = s2.iterator(); // Must be in the synchronized block |
1744 |
* while (i.hasNext()) |
1745 |
* foo(i.next()); |
1746 |
* } |
1747 |
* </pre> |
1748 |
* Failure to follow this advice may result in non-deterministic behavior. |
1749 |
* |
1750 |
* <p>The returned sorted set will be serializable if the specified |
1751 |
* sorted set is serializable. |
1752 |
* |
1753 |
* @param s the sorted set to be "wrapped" in a synchronized sorted set. |
1754 |
* @return a synchronized view of the specified sorted set. |
1755 |
*/ |
1756 |
public static <T> SortedSet<T> synchronizedSortedSet(SortedSet<T> s) { |
1757 |
return new SynchronizedSortedSet<T>(s); |
1758 |
} |
1759 |
|
1760 |
/** |
1761 |
* @serial include |
1762 |
*/ |
1763 |
static class SynchronizedSortedSet<E> |
1764 |
extends SynchronizedSet<E> |
1765 |
implements SortedSet<E> |
1766 |
{ |
1767 |
private static final long serialVersionUID = 8695801310862127406L; |
1768 |
|
1769 |
private final SortedSet<E> ss; |
1770 |
|
1771 |
SynchronizedSortedSet(SortedSet<E> s) { |
1772 |
super(s); |
1773 |
ss = s; |
1774 |
} |
1775 |
SynchronizedSortedSet(SortedSet<E> s, Object mutex) { |
1776 |
super(s, mutex); |
1777 |
ss = s; |
1778 |
} |
1779 |
|
1780 |
public Comparator<? super E> comparator() { |
1781 |
synchronized (mutex) {return ss.comparator();} |
1782 |
} |
1783 |
|
1784 |
public SortedSet<E> subSet(E fromElement, E toElement) { |
1785 |
synchronized (mutex) { |
1786 |
return new SynchronizedSortedSet<E>( |
1787 |
ss.subSet(fromElement, toElement), mutex); |
1788 |
} |
1789 |
} |
1790 |
public SortedSet<E> headSet(E toElement) { |
1791 |
synchronized (mutex) { |
1792 |
return new SynchronizedSortedSet<E>(ss.headSet(toElement), mutex); |
1793 |
} |
1794 |
} |
1795 |
public SortedSet<E> tailSet(E fromElement) { |
1796 |
synchronized (mutex) { |
1797 |
return new SynchronizedSortedSet<E>(ss.tailSet(fromElement),mutex); |
1798 |
} |
1799 |
} |
1800 |
|
1801 |
public E first() { |
1802 |
synchronized (mutex) {return ss.first();} |
1803 |
} |
1804 |
public E last() { |
1805 |
synchronized (mutex) {return ss.last();} |
1806 |
} |
1807 |
} |
1808 |
|
1809 |
/** |
1810 |
* Returns a synchronized (thread-safe) list backed by the specified |
1811 |
* list. In order to guarantee serial access, it is critical that |
1812 |
* <strong>all</strong> access to the backing list is accomplished |
1813 |
* through the returned list.<p> |
1814 |
* |
1815 |
* It is imperative that the user manually synchronize on the returned |
1816 |
* list when iterating over it: |
1817 |
* <pre> |
1818 |
* List list = Collections.synchronizedList(new ArrayList()); |
1819 |
* ... |
1820 |
* synchronized (list) { |
1821 |
* Iterator i = list.iterator(); // Must be in synchronized block |
1822 |
* while (i.hasNext()) |
1823 |
* foo(i.next()); |
1824 |
* } |
1825 |
* </pre> |
1826 |
* Failure to follow this advice may result in non-deterministic behavior. |
1827 |
* |
1828 |
* <p>The returned list will be serializable if the specified list is |
1829 |
* serializable. |
1830 |
* |
1831 |
* @param list the list to be "wrapped" in a synchronized list. |
1832 |
* @return a synchronized view of the specified list. |
1833 |
*/ |
1834 |
public static <T> List<T> synchronizedList(List<T> list) { |
1835 |
return (list instanceof RandomAccess ? |
1836 |
new SynchronizedRandomAccessList<T>(list) : |
1837 |
new SynchronizedList<T>(list)); |
1838 |
} |
1839 |
|
1840 |
static <T> List<T> synchronizedList(List<T> list, Object mutex) { |
1841 |
return (list instanceof RandomAccess ? |
1842 |
new SynchronizedRandomAccessList<T>(list, mutex) : |
1843 |
new SynchronizedList<T>(list, mutex)); |
1844 |
} |
1845 |
|
1846 |
/** |
1847 |
* @serial include |
1848 |
*/ |
1849 |
static class SynchronizedList<E> |
1850 |
extends SynchronizedCollection<E> |
1851 |
implements List<E> { |
1852 |
private static final long serialVersionUID = -7754090372962971524L; |
1853 |
|
1854 |
final List<E> list; |
1855 |
|
1856 |
SynchronizedList(List<E> list) { |
1857 |
super(list); |
1858 |
this.list = list; |
1859 |
} |
1860 |
SynchronizedList(List<E> list, Object mutex) { |
1861 |
super(list, mutex); |
1862 |
this.list = list; |
1863 |
} |
1864 |
|
1865 |
public boolean equals(Object o) { |
1866 |
synchronized (mutex) {return list.equals(o);} |
1867 |
} |
1868 |
public int hashCode() { |
1869 |
synchronized (mutex) {return list.hashCode();} |
1870 |
} |
1871 |
|
1872 |
public E get(int index) { |
1873 |
synchronized (mutex) {return list.get(index);} |
1874 |
} |
1875 |
public E set(int index, E element) { |
1876 |
synchronized (mutex) {return list.set(index, element);} |
1877 |
} |
1878 |
public void add(int index, E element) { |
1879 |
synchronized (mutex) {list.add(index, element);} |
1880 |
} |
1881 |
public E remove(int index) { |
1882 |
synchronized (mutex) {return list.remove(index);} |
1883 |
} |
1884 |
|
1885 |
public int indexOf(Object o) { |
1886 |
synchronized (mutex) {return list.indexOf(o);} |
1887 |
} |
1888 |
public int lastIndexOf(Object o) { |
1889 |
synchronized (mutex) {return list.lastIndexOf(o);} |
1890 |
} |
1891 |
|
1892 |
public boolean addAll(int index, Collection<? extends E> c) { |
1893 |
synchronized (mutex) {return list.addAll(index, c);} |
1894 |
} |
1895 |
|
1896 |
public ListIterator<E> listIterator() { |
1897 |
return list.listIterator(); // Must be manually synched by user |
1898 |
} |
1899 |
|
1900 |
public ListIterator<E> listIterator(int index) { |
1901 |
return list.listIterator(index); // Must be manually synched by user |
1902 |
} |
1903 |
|
1904 |
public List<E> subList(int fromIndex, int toIndex) { |
1905 |
synchronized (mutex) { |
1906 |
return new SynchronizedList<E>(list.subList(fromIndex, toIndex), |
1907 |
mutex); |
1908 |
} |
1909 |
} |
1910 |
|
1911 |
/** |
1912 |
* SynchronizedRandomAccessList instances are serialized as |
1913 |
* SynchronizedList instances to allow them to be deserialized |
1914 |
* in pre-1.4 JREs (which do not have SynchronizedRandomAccessList). |
1915 |
* This method inverts the transformation. As a beneficial |
1916 |
* side-effect, it also grafts the RandomAccess marker onto |
1917 |
* SynchronizedList instances that were serialized in pre-1.4 JREs. |
1918 |
* |
1919 |
* Note: Unfortunately, SynchronizedRandomAccessList instances |
1920 |
* serialized in 1.4.1 and deserialized in 1.4 will become |
1921 |
* SynchronizedList instances, as this method was missing in 1.4. |
1922 |
*/ |
1923 |
private Object readResolve() { |
1924 |
return (list instanceof RandomAccess |
1925 |
? new SynchronizedRandomAccessList<E>(list) |
1926 |
: this); |
1927 |
} |
1928 |
} |
1929 |
|
1930 |
/** |
1931 |
* @serial include |
1932 |
*/ |
1933 |
static class SynchronizedRandomAccessList<E> |
1934 |
extends SynchronizedList<E> |
1935 |
implements RandomAccess { |
1936 |
|
1937 |
SynchronizedRandomAccessList(List<E> list) { |
1938 |
super(list); |
1939 |
} |
1940 |
|
1941 |
SynchronizedRandomAccessList(List<E> list, Object mutex) { |
1942 |
super(list, mutex); |
1943 |
} |
1944 |
|
1945 |
public List<E> subList(int fromIndex, int toIndex) { |
1946 |
synchronized (mutex) { |
1947 |
return new SynchronizedRandomAccessList<E>( |
1948 |
list.subList(fromIndex, toIndex), mutex); |
1949 |
} |
1950 |
} |
1951 |
|
1952 |
private static final long serialVersionUID = 1530674583602358482L; |
1953 |
|
1954 |
/** |
1955 |
* Allows instances to be deserialized in pre-1.4 JREs (which do |
1956 |
* not have SynchronizedRandomAccessList). SynchronizedList has |
1957 |
* a readResolve method that inverts this transformation upon |
1958 |
* deserialization. |
1959 |
*/ |
1960 |
private Object writeReplace() { |
1961 |
return new SynchronizedList<E>(list); |
1962 |
} |
1963 |
} |
1964 |
|
1965 |
/** |
1966 |
* Returns a synchronized (thread-safe) map backed by the specified |
1967 |
* map. In order to guarantee serial access, it is critical that |
1968 |
* <strong>all</strong> access to the backing map is accomplished |
1969 |
* through the returned map.<p> |
1970 |
* |
1971 |
* It is imperative that the user manually synchronize on the returned |
1972 |
* map when iterating over any of its collection views: |
1973 |
* <pre> |
1974 |
* Map m = Collections.synchronizedMap(new HashMap()); |
1975 |
* ... |
1976 |
* Set s = m.keySet(); // Needn't be in synchronized block |
1977 |
* ... |
1978 |
* synchronized (m) { // Synchronizing on m, not s! |
1979 |
* Iterator i = s.iterator(); // Must be in synchronized block |
1980 |
* while (i.hasNext()) |
1981 |
* foo(i.next()); |
1982 |
* } |
1983 |
* </pre> |
1984 |
* Failure to follow this advice may result in non-deterministic behavior. |
1985 |
* |
1986 |
* <p>The returned map will be serializable if the specified map is |
1987 |
* serializable. |
1988 |
* |
1989 |
* @param m the map to be "wrapped" in a synchronized map. |
1990 |
* @return a synchronized view of the specified map. |
1991 |
*/ |
1992 |
public static <K,V> Map<K,V> synchronizedMap(Map<K,V> m) { |
1993 |
return new SynchronizedMap<K,V>(m); |
1994 |
} |
1995 |
|
1996 |
/** |
1997 |
* @serial include |
1998 |
*/ |
1999 |
private static class SynchronizedMap<K,V> |
2000 |
implements Map<K,V>, Serializable { |
2001 |
private static final long serialVersionUID = 1978198479659022715L; |
2002 |
|
2003 |
private final Map<K,V> m; // Backing Map |
2004 |
final Object mutex; // Object on which to synchronize |
2005 |
|
2006 |
SynchronizedMap(Map<K,V> m) { |
2007 |
if (m==null) |
2008 |
throw new NullPointerException(); |
2009 |
this.m = m; |
2010 |
mutex = this; |
2011 |
} |
2012 |
|
2013 |
SynchronizedMap(Map<K,V> m, Object mutex) { |
2014 |
this.m = m; |
2015 |
this.mutex = mutex; |
2016 |
} |
2017 |
|
2018 |
public int size() { |
2019 |
synchronized (mutex) {return m.size();} |
2020 |
} |
2021 |
public boolean isEmpty() { |
2022 |
synchronized (mutex) {return m.isEmpty();} |
2023 |
} |
2024 |
public boolean containsKey(Object key) { |
2025 |
synchronized (mutex) {return m.containsKey(key);} |
2026 |
} |
2027 |
public boolean containsValue(Object value) { |
2028 |
synchronized (mutex) {return m.containsValue(value);} |
2029 |
} |
2030 |
public V get(Object key) { |
2031 |
synchronized (mutex) {return m.get(key);} |
2032 |
} |
2033 |
|
2034 |
public V put(K key, V value) { |
2035 |
synchronized (mutex) {return m.put(key, value);} |
2036 |
} |
2037 |
public V remove(Object key) { |
2038 |
synchronized (mutex) {return m.remove(key);} |
2039 |
} |
2040 |
public void putAll(Map<? extends K, ? extends V> map) { |
2041 |
synchronized (mutex) {m.putAll(map);} |
2042 |
} |
2043 |
public void clear() { |
2044 |
synchronized (mutex) {m.clear();} |
2045 |
} |
2046 |
|
2047 |
private transient Set<K> keySet = null; |
2048 |
private transient Set<Map.Entry<K,V>> entrySet = null; |
2049 |
private transient Collection<V> values = null; |
2050 |
|
2051 |
public Set<K> keySet() { |
2052 |
synchronized (mutex) { |
2053 |
if (keySet==null) |
2054 |
keySet = new SynchronizedSet<K>(m.keySet(), mutex); |
2055 |
return keySet; |
2056 |
} |
2057 |
} |
2058 |
|
2059 |
public Set<Map.Entry<K,V>> entrySet() { |
2060 |
synchronized (mutex) { |
2061 |
if (entrySet==null) |
2062 |
entrySet = new SynchronizedSet<Map.Entry<K,V>>(m.entrySet(), mutex); |
2063 |
return entrySet; |
2064 |
} |
2065 |
} |
2066 |
|
2067 |
public Collection<V> values() { |
2068 |
synchronized (mutex) { |
2069 |
if (values==null) |
2070 |
values = new SynchronizedCollection<V>(m.values(), mutex); |
2071 |
return values; |
2072 |
} |
2073 |
} |
2074 |
|
2075 |
public boolean equals(Object o) { |
2076 |
synchronized (mutex) {return m.equals(o);} |
2077 |
} |
2078 |
public int hashCode() { |
2079 |
synchronized (mutex) {return m.hashCode();} |
2080 |
} |
2081 |
public String toString() { |
2082 |
synchronized (mutex) {return m.toString();} |
2083 |
} |
2084 |
private void writeObject(ObjectOutputStream s) throws IOException { |
2085 |
synchronized (mutex) {s.defaultWriteObject();} |
2086 |
} |
2087 |
} |
2088 |
|
2089 |
/** |
2090 |
* Returns a synchronized (thread-safe) sorted map backed by the specified |
2091 |
* sorted map. In order to guarantee serial access, it is critical that |
2092 |
* <strong>all</strong> access to the backing sorted map is accomplished |
2093 |
* through the returned sorted map (or its views).<p> |
2094 |
* |
2095 |
* It is imperative that the user manually synchronize on the returned |
2096 |
* sorted map when iterating over any of its collection views, or the |
2097 |
* collections views of any of its <tt>subMap</tt>, <tt>headMap</tt> or |
2098 |
* <tt>tailMap</tt> views. |
2099 |
* <pre> |
2100 |
* SortedMap m = Collections.synchronizedSortedMap(new TreeMap()); |
2101 |
* ... |
2102 |
* Set s = m.keySet(); // Needn't be in synchronized block |
2103 |
* ... |
2104 |
* synchronized (m) { // Synchronizing on m, not s! |
2105 |
* Iterator i = s.iterator(); // Must be in synchronized block |
2106 |
* while (i.hasNext()) |
2107 |
* foo(i.next()); |
2108 |
* } |
2109 |
* </pre> |
2110 |
* or: |
2111 |
* <pre> |
2112 |
* SortedMap m = Collections.synchronizedSortedMap(new TreeMap()); |
2113 |
* SortedMap m2 = m.subMap(foo, bar); |
2114 |
* ... |
2115 |
* Set s2 = m2.keySet(); // Needn't be in synchronized block |
2116 |
* ... |
2117 |
* synchronized (m) { // Synchronizing on m, not m2 or s2! |
2118 |
* Iterator i = s.iterator(); // Must be in synchronized block |
2119 |
* while (i.hasNext()) |
2120 |
* foo(i.next()); |
2121 |
* } |
2122 |
* </pre> |
2123 |
* Failure to follow this advice may result in non-deterministic behavior. |
2124 |
* |
2125 |
* <p>The returned sorted map will be serializable if the specified |
2126 |
* sorted map is serializable. |
2127 |
* |
2128 |
* @param m the sorted map to be "wrapped" in a synchronized sorted map. |
2129 |
* @return a synchronized view of the specified sorted map. |
2130 |
*/ |
2131 |
public static <K,V> SortedMap<K,V> synchronizedSortedMap(SortedMap<K,V> m) { |
2132 |
return new SynchronizedSortedMap<K,V>(m); |
2133 |
} |
2134 |
|
2135 |
|
2136 |
/** |
2137 |
* @serial include |
2138 |
*/ |
2139 |
static class SynchronizedSortedMap<K,V> |
2140 |
extends SynchronizedMap<K,V> |
2141 |
implements SortedMap<K,V> |
2142 |
{ |
2143 |
private static final long serialVersionUID = -8798146769416483793L; |
2144 |
|
2145 |
private final SortedMap<K,V> sm; |
2146 |
|
2147 |
SynchronizedSortedMap(SortedMap<K,V> m) { |
2148 |
super(m); |
2149 |
sm = m; |
2150 |
} |
2151 |
SynchronizedSortedMap(SortedMap<K,V> m, Object mutex) { |
2152 |
super(m, mutex); |
2153 |
sm = m; |
2154 |
} |
2155 |
|
2156 |
public Comparator<? super K> comparator() { |
2157 |
synchronized (mutex) {return sm.comparator();} |
2158 |
} |
2159 |
|
2160 |
public SortedMap<K,V> subMap(K fromKey, K toKey) { |
2161 |
synchronized (mutex) { |
2162 |
return new SynchronizedSortedMap<K,V>( |
2163 |
sm.subMap(fromKey, toKey), mutex); |
2164 |
} |
2165 |
} |
2166 |
public SortedMap<K,V> headMap(K toKey) { |
2167 |
synchronized (mutex) { |
2168 |
return new SynchronizedSortedMap<K,V>(sm.headMap(toKey), mutex); |
2169 |
} |
2170 |
} |
2171 |
public SortedMap<K,V> tailMap(K fromKey) { |
2172 |
synchronized (mutex) { |
2173 |
return new SynchronizedSortedMap<K,V>(sm.tailMap(fromKey),mutex); |
2174 |
} |
2175 |
} |
2176 |
|
2177 |
public K firstKey() { |
2178 |
synchronized (mutex) {return sm.firstKey();} |
2179 |
} |
2180 |
public K lastKey() { |
2181 |
synchronized (mutex) {return sm.lastKey();} |
2182 |
} |
2183 |
} |
2184 |
|
2185 |
// Dynamically typesafe collection wrappers |
2186 |
|
2187 |
/** |
2188 |
* Returns a dynamically typesafe view of the specified collection. |
2189 |
* Any attempt to insert an element of the wrong type will result in an |
2190 |
* immediate {@link ClassCastException}. Assuming a collection |
2191 |
* contains no incorrectly typed elements prior to the time a |
2192 |
* dynamically typesafe view is generated, and that all subsequent |
2193 |
* access to the collection takes place through the view, it is |
2194 |
* <i>guaranteed</i> that the collection cannot contain an incorrectly |
2195 |
* typed element. |
2196 |
* |
2197 |
* <p>The generics mechanism in the language provides compile-time |
2198 |
* (static) type checking, but it is possible to defeat this mechanism |
2199 |
* with unchecked casts. Usually this is not a problem, as the compiler |
2200 |
* issues warnings on all such unchecked operations. There are, however, |
2201 |
* times when static type checking alone is not sufficient. For example, |
2202 |
* suppose a collection is passed to a third-party library and it is |
2203 |
* imperative that the library code not corrupt the collection by |
2204 |
* inserting an element of the wrong type. |
2205 |
* |
2206 |
* <p>Another use of dynamically typesafe views is debugging. Suppose a |
2207 |
* program fails with a {@code ClassCastException}, indicating that an |
2208 |
* incorrectly typed element was put into a parameterized collection. |
2209 |
* Unfortunately, the exception can occur at any time after the erroneous |
2210 |
* element is inserted, so it typically provides little or no information |
2211 |
* as to the real source of the problem. If the problem is reproducible, |
2212 |
* one can quickly determine its source by temporarily modifying the |
2213 |
* program to wrap the collection with a dynamically typesafe view. |
2214 |
* For example, this declaration: |
2215 |
* <pre> {@code |
2216 |
* Collection<String> c = new HashSet<String>(); |
2217 |
* }</pre> |
2218 |
* may be replaced temporarily by this one: |
2219 |
* <pre> {@code |
2220 |
* Collection<String> c = Collections.checkedCollection( |
2221 |
* new HashSet<String>(), String.class); |
2222 |
* }</pre> |
2223 |
* Running the program again will cause it to fail at the point where |
2224 |
* an incorrectly typed element is inserted into the collection, clearly |
2225 |
* identifying the source of the problem. Once the problem is fixed, the |
2226 |
* modified declaration may be reverted back to the original. |
2227 |
* |
2228 |
* <p>The returned collection does <i>not</i> pass the hashCode and equals |
2229 |
* operations through to the backing collection, but relies on |
2230 |
* {@code Object}'s {@code equals} and {@code hashCode} methods. This |
2231 |
* is necessary to preserve the contracts of these operations in the case |
2232 |
* that the backing collection is a set or a list. |
2233 |
* |
2234 |
* <p>The returned collection will be serializable if the specified |
2235 |
* collection is serializable. |
2236 |
* |
2237 |
* <p>Since {@code null} is considered to be a value of any reference |
2238 |
* type, the returned collection permits insertion of null elements |
2239 |
* whenever the backing collection does. |
2240 |
* |
2241 |
* @param c the collection for which a dynamically typesafe view is to be |
2242 |
* returned |
2243 |
* @param type the type of element that {@code c} is permitted to hold |
2244 |
* @return a dynamically typesafe view of the specified collection |
2245 |
* @since 1.5 |
2246 |
*/ |
2247 |
public static <E> Collection<E> checkedCollection(Collection<E> c, |
2248 |
Class<E> type) { |
2249 |
return new CheckedCollection<E>(c, type); |
2250 |
} |
2251 |
|
2252 |
@SuppressWarnings("unchecked") |
2253 |
static <T> T[] zeroLengthArray(Class<T> type) { |
2254 |
return (T[]) Array.newInstance(type, 0); |
2255 |
} |
2256 |
|
2257 |
/** |
2258 |
* @serial include |
2259 |
*/ |
2260 |
static class CheckedCollection<E> implements Collection<E>, Serializable { |
2261 |
private static final long serialVersionUID = 1578914078182001775L; |
2262 |
|
2263 |
final Collection<E> c; |
2264 |
final Class<E> type; |
2265 |
|
2266 |
void typeCheck(Object o) { |
2267 |
if (o != null && !type.isInstance(o)) |
2268 |
throw new ClassCastException(badElementMsg(o)); |
2269 |
} |
2270 |
|
2271 |
private String badElementMsg(Object o) { |
2272 |
return "Attempt to insert " + o.getClass() + |
2273 |
" element into collection with element type " + type; |
2274 |
} |
2275 |
|
2276 |
CheckedCollection(Collection<E> c, Class<E> type) { |
2277 |
if (c==null || type == null) |
2278 |
throw new NullPointerException(); |
2279 |
this.c = c; |
2280 |
this.type = type; |
2281 |
} |
2282 |
|
2283 |
public int size() { return c.size(); } |
2284 |
public boolean isEmpty() { return c.isEmpty(); } |
2285 |
public boolean contains(Object o) { return c.contains(o); } |
2286 |
public Object[] toArray() { return c.toArray(); } |
2287 |
public <T> T[] toArray(T[] a) { return c.toArray(a); } |
2288 |
public String toString() { return c.toString(); } |
2289 |
public boolean remove(Object o) { return c.remove(o); } |
2290 |
public void clear() { c.clear(); } |
2291 |
|
2292 |
public boolean containsAll(Collection<?> coll) { |
2293 |
return c.containsAll(coll); |
2294 |
} |
2295 |
public boolean removeAll(Collection<?> coll) { |
2296 |
return c.removeAll(coll); |
2297 |
} |
2298 |
public boolean retainAll(Collection<?> coll) { |
2299 |
return c.retainAll(coll); |
2300 |
} |
2301 |
|
2302 |
public Iterator<E> iterator() { |
2303 |
final Iterator<E> it = c.iterator(); |
2304 |
return new Iterator<E>() { |
2305 |
public boolean hasNext() { return it.hasNext(); } |
2306 |
public E next() { return it.next(); } |
2307 |
public void remove() { it.remove(); }}; |
2308 |
} |
2309 |
|
2310 |
public boolean add(E e) { |
2311 |
typeCheck(e); |
2312 |
return c.add(e); |
2313 |
} |
2314 |
|
2315 |
private E[] zeroLengthElementArray = null; // Lazily initialized |
2316 |
|
2317 |
private E[] zeroLengthElementArray() { |
2318 |
return zeroLengthElementArray != null ? zeroLengthElementArray : |
2319 |
(zeroLengthElementArray = zeroLengthArray(type)); |
2320 |
} |
2321 |
|
2322 |
@SuppressWarnings("unchecked") |
2323 |
Collection<E> checkedCopyOf(Collection<? extends E> coll) { |
2324 |
Object[] a = null; |
2325 |
try { |
2326 |
E[] z = zeroLengthElementArray(); |
2327 |
a = coll.toArray(z); |
2328 |
// Defend against coll violating the toArray contract |
2329 |
if (a.getClass() != z.getClass()) |
2330 |
a = Arrays.copyOf(a, a.length, z.getClass()); |
2331 |
} catch (ArrayStoreException ignore) { |
2332 |
// To get better and consistent diagnostics, |
2333 |
// we call typeCheck explicitly on each element. |
2334 |
// We call clone() to defend against coll retaining a |
2335 |
// reference to the returned array and storing a bad |
2336 |
// element into it after it has been type checked. |
2337 |
a = coll.toArray().clone(); |
2338 |
for (Object o : a) |
2339 |
typeCheck(o); |
2340 |
} |
2341 |
// A slight abuse of the type system, but safe here. |
2342 |
return (Collection<E>) Arrays.asList(a); |
2343 |
} |
2344 |
|
2345 |
public boolean addAll(Collection<? extends E> coll) { |
2346 |
// Doing things this way insulates us from concurrent changes |
2347 |
// in the contents of coll and provides all-or-nothing |
2348 |
// semantics (which we wouldn't get if we type-checked each |
2349 |
// element as we added it) |
2350 |
return c.addAll(checkedCopyOf(coll)); |
2351 |
} |
2352 |
} |
2353 |
|
2354 |
/** |
2355 |
* Returns a dynamically typesafe view of the specified set. |
2356 |
* Any attempt to insert an element of the wrong type will result in |
2357 |
* an immediate {@link ClassCastException}. Assuming a set contains |
2358 |
* no incorrectly typed elements prior to the time a dynamically typesafe |
2359 |
* view is generated, and that all subsequent access to the set |
2360 |
* takes place through the view, it is <i>guaranteed</i> that the |
2361 |
* set cannot contain an incorrectly typed element. |
2362 |
* |
2363 |
* <p>A discussion of the use of dynamically typesafe views may be |
2364 |
* found in the documentation for the {@link #checkedCollection |
2365 |
* checkedCollection} method. |
2366 |
* |
2367 |
* <p>The returned set will be serializable if the specified set is |
2368 |
* serializable. |
2369 |
* |
2370 |
* <p>Since {@code null} is considered to be a value of any reference |
2371 |
* type, the returned set permits insertion of null elements whenever |
2372 |
* the backing set does. |
2373 |
* |
2374 |
* @param s the set for which a dynamically typesafe view is to be |
2375 |
* returned |
2376 |
* @param type the type of element that {@code s} is permitted to hold |
2377 |
* @return a dynamically typesafe view of the specified set |
2378 |
* @since 1.5 |
2379 |
*/ |
2380 |
public static <E> Set<E> checkedSet(Set<E> s, Class<E> type) { |
2381 |
return new CheckedSet<E>(s, type); |
2382 |
} |
2383 |
|
2384 |
/** |
2385 |
* @serial include |
2386 |
*/ |
2387 |
static class CheckedSet<E> extends CheckedCollection<E> |
2388 |
implements Set<E>, Serializable |
2389 |
{ |
2390 |
private static final long serialVersionUID = 4694047833775013803L; |
2391 |
|
2392 |
CheckedSet(Set<E> s, Class<E> elementType) { super(s, elementType); } |
2393 |
|
2394 |
public boolean equals(Object o) { return o == this || c.equals(o); } |
2395 |
public int hashCode() { return c.hashCode(); } |
2396 |
} |
2397 |
|
2398 |
/** |
2399 |
* Returns a dynamically typesafe view of the specified sorted set. |
2400 |
* Any attempt to insert an element of the wrong type will result in an |
2401 |
* immediate {@link ClassCastException}. Assuming a sorted set |
2402 |
* contains no incorrectly typed elements prior to the time a |
2403 |
* dynamically typesafe view is generated, and that all subsequent |
2404 |
* access to the sorted set takes place through the view, it is |
2405 |
* <i>guaranteed</i> that the sorted set cannot contain an incorrectly |
2406 |
* typed element. |
2407 |
* |
2408 |
* <p>A discussion of the use of dynamically typesafe views may be |
2409 |
* found in the documentation for the {@link #checkedCollection |
2410 |
* checkedCollection} method. |
2411 |
* |
2412 |
* <p>The returned sorted set will be serializable if the specified sorted |
2413 |
* set is serializable. |
2414 |
* |
2415 |
* <p>Since {@code null} is considered to be a value of any reference |
2416 |
* type, the returned sorted set permits insertion of null elements |
2417 |
* whenever the backing sorted set does. |
2418 |
* |
2419 |
* @param s the sorted set for which a dynamically typesafe view is to be |
2420 |
* returned |
2421 |
* @param type the type of element that {@code s} is permitted to hold |
2422 |
* @return a dynamically typesafe view of the specified sorted set |
2423 |
* @since 1.5 |
2424 |
*/ |
2425 |
public static <E> SortedSet<E> checkedSortedSet(SortedSet<E> s, |
2426 |
Class<E> type) { |
2427 |
return new CheckedSortedSet<E>(s, type); |
2428 |
} |
2429 |
|
2430 |
/** |
2431 |
* @serial include |
2432 |
*/ |
2433 |
static class CheckedSortedSet<E> extends CheckedSet<E> |
2434 |
implements SortedSet<E>, Serializable |
2435 |
{ |
2436 |
private static final long serialVersionUID = 1599911165492914959L; |
2437 |
private final SortedSet<E> ss; |
2438 |
|
2439 |
CheckedSortedSet(SortedSet<E> s, Class<E> type) { |
2440 |
super(s, type); |
2441 |
ss = s; |
2442 |
} |
2443 |
|
2444 |
public Comparator<? super E> comparator() { return ss.comparator(); } |
2445 |
public E first() { return ss.first(); } |
2446 |
public E last() { return ss.last(); } |
2447 |
|
2448 |
public SortedSet<E> subSet(E fromElement, E toElement) { |
2449 |
return checkedSortedSet(ss.subSet(fromElement,toElement), type); |
2450 |
} |
2451 |
public SortedSet<E> headSet(E toElement) { |
2452 |
return checkedSortedSet(ss.headSet(toElement), type); |
2453 |
} |
2454 |
public SortedSet<E> tailSet(E fromElement) { |
2455 |
return checkedSortedSet(ss.tailSet(fromElement), type); |
2456 |
} |
2457 |
} |
2458 |
|
2459 |
/** |
2460 |
* Returns a dynamically typesafe view of the specified list. |
2461 |
* Any attempt to insert an element of the wrong type will result in |
2462 |
* an immediate {@link ClassCastException}. Assuming a list contains |
2463 |
* no incorrectly typed elements prior to the time a dynamically typesafe |
2464 |
* view is generated, and that all subsequent access to the list |
2465 |
* takes place through the view, it is <i>guaranteed</i> that the |
2466 |
* list cannot contain an incorrectly typed element. |
2467 |
* |
2468 |
* <p>A discussion of the use of dynamically typesafe views may be |
2469 |
* found in the documentation for the {@link #checkedCollection |
2470 |
* checkedCollection} method. |
2471 |
* |
2472 |
* <p>The returned list will be serializable if the specified list |
2473 |
* is serializable. |
2474 |
* |
2475 |
* <p>Since {@code null} is considered to be a value of any reference |
2476 |
* type, the returned list permits insertion of null elements whenever |
2477 |
* the backing list does. |
2478 |
* |
2479 |
* @param list the list for which a dynamically typesafe view is to be |
2480 |
* returned |
2481 |
* @param type the type of element that {@code list} is permitted to hold |
2482 |
* @return a dynamically typesafe view of the specified list |
2483 |
* @since 1.5 |
2484 |
*/ |
2485 |
public static <E> List<E> checkedList(List<E> list, Class<E> type) { |
2486 |
return (list instanceof RandomAccess ? |
2487 |
new CheckedRandomAccessList<E>(list, type) : |
2488 |
new CheckedList<E>(list, type)); |
2489 |
} |
2490 |
|
2491 |
/** |
2492 |
* @serial include |
2493 |
*/ |
2494 |
static class CheckedList<E> |
2495 |
extends CheckedCollection<E> |
2496 |
implements List<E> |
2497 |
{ |
2498 |
private static final long serialVersionUID = 65247728283967356L; |
2499 |
final List<E> list; |
2500 |
|
2501 |
CheckedList(List<E> list, Class<E> type) { |
2502 |
super(list, type); |
2503 |
this.list = list; |
2504 |
} |
2505 |
|
2506 |
public boolean equals(Object o) { return o == this || list.equals(o); } |
2507 |
public int hashCode() { return list.hashCode(); } |
2508 |
public E get(int index) { return list.get(index); } |
2509 |
public E remove(int index) { return list.remove(index); } |
2510 |
public int indexOf(Object o) { return list.indexOf(o); } |
2511 |
public int lastIndexOf(Object o) { return list.lastIndexOf(o); } |
2512 |
|
2513 |
public E set(int index, E element) { |
2514 |
typeCheck(element); |
2515 |
return list.set(index, element); |
2516 |
} |
2517 |
|
2518 |
public void add(int index, E element) { |
2519 |
typeCheck(element); |
2520 |
list.add(index, element); |
2521 |
} |
2522 |
|
2523 |
public boolean addAll(int index, Collection<? extends E> c) { |
2524 |
return list.addAll(index, checkedCopyOf(c)); |
2525 |
} |
2526 |
public ListIterator<E> listIterator() { return listIterator(0); } |
2527 |
|
2528 |
public ListIterator<E> listIterator(final int index) { |
2529 |
final ListIterator<E> i = list.listIterator(index); |
2530 |
|
2531 |
return new ListIterator<E>() { |
2532 |
public boolean hasNext() { return i.hasNext(); } |
2533 |
public E next() { return i.next(); } |
2534 |
public boolean hasPrevious() { return i.hasPrevious(); } |
2535 |
public E previous() { return i.previous(); } |
2536 |
public int nextIndex() { return i.nextIndex(); } |
2537 |
public int previousIndex() { return i.previousIndex(); } |
2538 |
public void remove() { i.remove(); } |
2539 |
|
2540 |
public void set(E e) { |
2541 |
typeCheck(e); |
2542 |
i.set(e); |
2543 |
} |
2544 |
|
2545 |
public void add(E e) { |
2546 |
typeCheck(e); |
2547 |
i.add(e); |
2548 |
} |
2549 |
}; |
2550 |
} |
2551 |
|
2552 |
public List<E> subList(int fromIndex, int toIndex) { |
2553 |
return new CheckedList<E>(list.subList(fromIndex, toIndex), type); |
2554 |
} |
2555 |
} |
2556 |
|
2557 |
/** |
2558 |
* @serial include |
2559 |
*/ |
2560 |
static class CheckedRandomAccessList<E> extends CheckedList<E> |
2561 |
implements RandomAccess |
2562 |
{ |
2563 |
private static final long serialVersionUID = 1638200125423088369L; |
2564 |
|
2565 |
CheckedRandomAccessList(List<E> list, Class<E> type) { |
2566 |
super(list, type); |
2567 |
} |
2568 |
|
2569 |
public List<E> subList(int fromIndex, int toIndex) { |
2570 |
return new CheckedRandomAccessList<E>( |
2571 |
list.subList(fromIndex, toIndex), type); |
2572 |
} |
2573 |
} |
2574 |
|
2575 |
/** |
2576 |
* Returns a dynamically typesafe view of the specified map. |
2577 |
* Any attempt to insert a mapping whose key or value have the wrong |
2578 |
* type will result in an immediate {@link ClassCastException}. |
2579 |
* Similarly, any attempt to modify the value currently associated with |
2580 |
* a key will result in an immediate {@link ClassCastException}, |
2581 |
* whether the modification is attempted directly through the map |
2582 |
* itself, or through a {@link Map.Entry} instance obtained from the |
2583 |
* map's {@link Map#entrySet() entry set} view. |
2584 |
* |
2585 |
* <p>Assuming a map contains no incorrectly typed keys or values |
2586 |
* prior to the time a dynamically typesafe view is generated, and |
2587 |
* that all subsequent access to the map takes place through the view |
2588 |
* (or one of its collection views), it is <i>guaranteed</i> that the |
2589 |
* map cannot contain an incorrectly typed key or value. |
2590 |
* |
2591 |
* <p>A discussion of the use of dynamically typesafe views may be |
2592 |
* found in the documentation for the {@link #checkedCollection |
2593 |
* checkedCollection} method. |
2594 |
* |
2595 |
* <p>The returned map will be serializable if the specified map is |
2596 |
* serializable. |
2597 |
* |
2598 |
* <p>Since {@code null} is considered to be a value of any reference |
2599 |
* type, the returned map permits insertion of null keys or values |
2600 |
* whenever the backing map does. |
2601 |
* |
2602 |
* @param m the map for which a dynamically typesafe view is to be |
2603 |
* returned |
2604 |
* @param keyType the type of key that {@code m} is permitted to hold |
2605 |
* @param valueType the type of value that {@code m} is permitted to hold |
2606 |
* @return a dynamically typesafe view of the specified map |
2607 |
* @since 1.5 |
2608 |
*/ |
2609 |
public static <K, V> Map<K, V> checkedMap(Map<K, V> m, |
2610 |
Class<K> keyType, |
2611 |
Class<V> valueType) { |
2612 |
return new CheckedMap<K,V>(m, keyType, valueType); |
2613 |
} |
2614 |
|
2615 |
|
2616 |
/** |
2617 |
* @serial include |
2618 |
*/ |
2619 |
private static class CheckedMap<K,V> |
2620 |
implements Map<K,V>, Serializable |
2621 |
{ |
2622 |
private static final long serialVersionUID = 5742860141034234728L; |
2623 |
|
2624 |
private final Map<K, V> m; |
2625 |
final Class<K> keyType; |
2626 |
final Class<V> valueType; |
2627 |
|
2628 |
private void typeCheck(Object key, Object value) { |
2629 |
if (key != null && !keyType.isInstance(key)) |
2630 |
throw new ClassCastException(badKeyMsg(key)); |
2631 |
|
2632 |
if (value != null && !valueType.isInstance(value)) |
2633 |
throw new ClassCastException(badValueMsg(value)); |
2634 |
} |
2635 |
|
2636 |
private String badKeyMsg(Object key) { |
2637 |
return "Attempt to insert " + key.getClass() + |
2638 |
" key into map with key type " + keyType; |
2639 |
} |
2640 |
|
2641 |
private String badValueMsg(Object value) { |
2642 |
return "Attempt to insert " + value.getClass() + |
2643 |
" value into map with value type " + valueType; |
2644 |
} |
2645 |
|
2646 |
CheckedMap(Map<K, V> m, Class<K> keyType, Class<V> valueType) { |
2647 |
if (m == null || keyType == null || valueType == null) |
2648 |
throw new NullPointerException(); |
2649 |
this.m = m; |
2650 |
this.keyType = keyType; |
2651 |
this.valueType = valueType; |
2652 |
} |
2653 |
|
2654 |
public int size() { return m.size(); } |
2655 |
public boolean isEmpty() { return m.isEmpty(); } |
2656 |
public boolean containsKey(Object key) { return m.containsKey(key); } |
2657 |
public boolean containsValue(Object v) { return m.containsValue(v); } |
2658 |
public V get(Object key) { return m.get(key); } |
2659 |
public V remove(Object key) { return m.remove(key); } |
2660 |
public void clear() { m.clear(); } |
2661 |
public Set<K> keySet() { return m.keySet(); } |
2662 |
public Collection<V> values() { return m.values(); } |
2663 |
public boolean equals(Object o) { return o == this || m.equals(o); } |
2664 |
public int hashCode() { return m.hashCode(); } |
2665 |
public String toString() { return m.toString(); } |
2666 |
|
2667 |
public V put(K key, V value) { |
2668 |
typeCheck(key, value); |
2669 |
return m.put(key, value); |
2670 |
} |
2671 |
|
2672 |
@SuppressWarnings("unchecked") |
2673 |
public void putAll(Map<? extends K, ? extends V> t) { |
2674 |
// Satisfy the following goals: |
2675 |
// - good diagnostics in case of type mismatch |
2676 |
// - all-or-nothing semantics |
2677 |
// - protection from malicious t |
2678 |
// - correct behavior if t is a concurrent map |
2679 |
Object[] entries = t.entrySet().toArray(); |
2680 |
List<Map.Entry<K,V>> checked = |
2681 |
new ArrayList<Map.Entry<K,V>>(entries.length); |
2682 |
for (Object o : entries) { |
2683 |
Map.Entry<?,?> e = (Map.Entry<?,?>) o; |
2684 |
Object k = e.getKey(); |
2685 |
Object v = e.getValue(); |
2686 |
typeCheck(k, v); |
2687 |
checked.add( |
2688 |
new AbstractMap.SimpleImmutableEntry<K,V>((K) k, (V) v)); |
2689 |
} |
2690 |
for (Map.Entry<K,V> e : checked) |
2691 |
m.put(e.getKey(), e.getValue()); |
2692 |
} |
2693 |
|
2694 |
private transient Set<Map.Entry<K,V>> entrySet = null; |
2695 |
|
2696 |
public Set<Map.Entry<K,V>> entrySet() { |
2697 |
if (entrySet==null) |
2698 |
entrySet = new CheckedEntrySet<K,V>(m.entrySet(), valueType); |
2699 |
return entrySet; |
2700 |
} |
2701 |
|
2702 |
/** |
2703 |
* We need this class in addition to CheckedSet as Map.Entry permits |
2704 |
* modification of the backing Map via the setValue operation. This |
2705 |
* class is subtle: there are many possible attacks that must be |
2706 |
* thwarted. |
2707 |
* |
2708 |
* @serial exclude |
2709 |
*/ |
2710 |
static class CheckedEntrySet<K,V> implements Set<Map.Entry<K,V>> { |
2711 |
private final Set<Map.Entry<K,V>> s; |
2712 |
private final Class<V> valueType; |
2713 |
|
2714 |
CheckedEntrySet(Set<Map.Entry<K, V>> s, Class<V> valueType) { |
2715 |
this.s = s; |
2716 |
this.valueType = valueType; |
2717 |
} |
2718 |
|
2719 |
public int size() { return s.size(); } |
2720 |
public boolean isEmpty() { return s.isEmpty(); } |
2721 |
public String toString() { return s.toString(); } |
2722 |
public int hashCode() { return s.hashCode(); } |
2723 |
public void clear() { s.clear(); } |
2724 |
|
2725 |
public boolean add(Map.Entry<K, V> e) { |
2726 |
throw new UnsupportedOperationException(); |
2727 |
} |
2728 |
public boolean addAll(Collection<? extends Map.Entry<K, V>> coll) { |
2729 |
throw new UnsupportedOperationException(); |
2730 |
} |
2731 |
|
2732 |
public Iterator<Map.Entry<K,V>> iterator() { |
2733 |
final Iterator<Map.Entry<K, V>> i = s.iterator(); |
2734 |
final Class<V> valueType = this.valueType; |
2735 |
|
2736 |
return new Iterator<Map.Entry<K,V>>() { |
2737 |
public boolean hasNext() { return i.hasNext(); } |
2738 |
public void remove() { i.remove(); } |
2739 |
|
2740 |
public Map.Entry<K,V> next() { |
2741 |
return checkedEntry(i.next(), valueType); |
2742 |
} |
2743 |
}; |
2744 |
} |
2745 |
|
2746 |
@SuppressWarnings("unchecked") |
2747 |
public Object[] toArray() { |
2748 |
Object[] source = s.toArray(); |
2749 |
|
2750 |
/* |
2751 |
* Ensure that we don't get an ArrayStoreException even if |
2752 |
* s.toArray returns an array of something other than Object |
2753 |
*/ |
2754 |
Object[] dest = (CheckedEntry.class.isInstance( |
2755 |
source.getClass().getComponentType()) ? source : |
2756 |
new Object[source.length]); |
2757 |
|
2758 |
for (int i = 0; i < source.length; i++) |
2759 |
dest[i] = checkedEntry((Map.Entry<K,V>)source[i], |
2760 |
valueType); |
2761 |
return dest; |
2762 |
} |
2763 |
|
2764 |
@SuppressWarnings("unchecked") |
2765 |
public <T> T[] toArray(T[] a) { |
2766 |
// We don't pass a to s.toArray, to avoid window of |
2767 |
// vulnerability wherein an unscrupulous multithreaded client |
2768 |
// could get his hands on raw (unwrapped) Entries from s. |
2769 |
T[] arr = s.toArray(a.length==0 ? a : Arrays.copyOf(a, 0)); |
2770 |
|
2771 |
for (int i=0; i<arr.length; i++) |
2772 |
arr[i] = (T) checkedEntry((Map.Entry<K,V>)arr[i], |
2773 |
valueType); |
2774 |
if (arr.length > a.length) |
2775 |
return arr; |
2776 |
|
2777 |
System.arraycopy(arr, 0, a, 0, arr.length); |
2778 |
if (a.length > arr.length) |
2779 |
a[arr.length] = null; |
2780 |
return a; |
2781 |
} |
2782 |
|
2783 |
/** |
2784 |
* This method is overridden to protect the backing set against |
2785 |
* an object with a nefarious equals function that senses |
2786 |
* that the equality-candidate is Map.Entry and calls its |
2787 |
* setValue method. |
2788 |
*/ |
2789 |
public boolean contains(Object o) { |
2790 |
if (!(o instanceof Map.Entry)) |
2791 |
return false; |
2792 |
Map.Entry<?,?> e = (Map.Entry<?,?>) o; |
2793 |
return s.contains( |
2794 |
(e instanceof CheckedEntry) ? e : checkedEntry(e, valueType)); |
2795 |
} |
2796 |
|
2797 |
/** |
2798 |
* The bulk collection methods are overridden to protect |
2799 |
* against an unscrupulous collection whose contains(Object o) |
2800 |
* method senses when o is a Map.Entry, and calls o.setValue. |
2801 |
*/ |
2802 |
public boolean containsAll(Collection<?> c) { |
2803 |
for (Object o : c) |
2804 |
if (!contains(o)) // Invokes safe contains() above |
2805 |
return false; |
2806 |
return true; |
2807 |
} |
2808 |
|
2809 |
public boolean remove(Object o) { |
2810 |
if (!(o instanceof Map.Entry)) |
2811 |
return false; |
2812 |
return s.remove(new AbstractMap.SimpleImmutableEntry |
2813 |
<Object, Object>((Map.Entry<?,?>)o)); |
2814 |
} |
2815 |
|
2816 |
public boolean removeAll(Collection<?> c) { |
2817 |
return batchRemove(c, false); |
2818 |
} |
2819 |
public boolean retainAll(Collection<?> c) { |
2820 |
return batchRemove(c, true); |
2821 |
} |
2822 |
private boolean batchRemove(Collection<?> c, boolean complement) { |
2823 |
boolean modified = false; |
2824 |
Iterator<Map.Entry<K,V>> it = iterator(); |
2825 |
while (it.hasNext()) { |
2826 |
if (c.contains(it.next()) != complement) { |
2827 |
it.remove(); |
2828 |
modified = true; |
2829 |
} |
2830 |
} |
2831 |
return modified; |
2832 |
} |
2833 |
|
2834 |
public boolean equals(Object o) { |
2835 |
if (o == this) |
2836 |
return true; |
2837 |
if (!(o instanceof Set)) |
2838 |
return false; |
2839 |
Set<?> that = (Set<?>) o; |
2840 |
return that.size() == s.size() |
2841 |
&& containsAll(that); // Invokes safe containsAll() above |
2842 |
} |
2843 |
|
2844 |
static <K,V,T> CheckedEntry<K,V,T> checkedEntry(Map.Entry<K,V> e, |
2845 |
Class<T> valueType) { |
2846 |
return new CheckedEntry<K,V,T>(e, valueType); |
2847 |
} |
2848 |
|
2849 |
/** |
2850 |
* This "wrapper class" serves two purposes: it prevents |
2851 |
* the client from modifying the backing Map, by short-circuiting |
2852 |
* the setValue method, and it protects the backing Map against |
2853 |
* an ill-behaved Map.Entry that attempts to modify another |
2854 |
* Map.Entry when asked to perform an equality check. |
2855 |
*/ |
2856 |
private static class CheckedEntry<K,V,T> implements Map.Entry<K,V> { |
2857 |
private final Map.Entry<K, V> e; |
2858 |
private final Class<T> valueType; |
2859 |
|
2860 |
CheckedEntry(Map.Entry<K, V> e, Class<T> valueType) { |
2861 |
this.e = e; |
2862 |
this.valueType = valueType; |
2863 |
} |
2864 |
|
2865 |
public K getKey() { return e.getKey(); } |
2866 |
public V getValue() { return e.getValue(); } |
2867 |
public int hashCode() { return e.hashCode(); } |
2868 |
public String toString() { return e.toString(); } |
2869 |
|
2870 |
public V setValue(V value) { |
2871 |
if (value != null && !valueType.isInstance(value)) |
2872 |
throw new ClassCastException(badValueMsg(value)); |
2873 |
return e.setValue(value); |
2874 |
} |
2875 |
|
2876 |
private String badValueMsg(Object value) { |
2877 |
return "Attempt to insert " + value.getClass() + |
2878 |
" value into map with value type " + valueType; |
2879 |
} |
2880 |
|
2881 |
public boolean equals(Object o) { |
2882 |
if (o == this) |
2883 |
return true; |
2884 |
if (!(o instanceof Map.Entry)) |
2885 |
return false; |
2886 |
return e.equals(new AbstractMap.SimpleImmutableEntry |
2887 |
<Object, Object>((Map.Entry<?,?>)o)); |
2888 |
} |
2889 |
} |
2890 |
} |
2891 |
} |
2892 |
|
2893 |
/** |
2894 |
* Returns a dynamically typesafe view of the specified sorted map. |
2895 |
* Any attempt to insert a mapping whose key or value have the wrong |
2896 |
* type will result in an immediate {@link ClassCastException}. |
2897 |
* Similarly, any attempt to modify the value currently associated with |
2898 |
* a key will result in an immediate {@link ClassCastException}, |
2899 |
* whether the modification is attempted directly through the map |
2900 |
* itself, or through a {@link Map.Entry} instance obtained from the |
2901 |
* map's {@link Map#entrySet() entry set} view. |
2902 |
* |
2903 |
* <p>Assuming a map contains no incorrectly typed keys or values |
2904 |
* prior to the time a dynamically typesafe view is generated, and |
2905 |
* that all subsequent access to the map takes place through the view |
2906 |
* (or one of its collection views), it is <i>guaranteed</i> that the |
2907 |
* map cannot contain an incorrectly typed key or value. |
2908 |
* |
2909 |
* <p>A discussion of the use of dynamically typesafe views may be |
2910 |
* found in the documentation for the {@link #checkedCollection |
2911 |
* checkedCollection} method. |
2912 |
* |
2913 |
* <p>The returned map will be serializable if the specified map is |
2914 |
* serializable. |
2915 |
* |
2916 |
* <p>Since {@code null} is considered to be a value of any reference |
2917 |
* type, the returned map permits insertion of null keys or values |
2918 |
* whenever the backing map does. |
2919 |
* |
2920 |
* @param m the map for which a dynamically typesafe view is to be |
2921 |
* returned |
2922 |
* @param keyType the type of key that {@code m} is permitted to hold |
2923 |
* @param valueType the type of value that {@code m} is permitted to hold |
2924 |
* @return a dynamically typesafe view of the specified map |
2925 |
* @since 1.5 |
2926 |
*/ |
2927 |
public static <K,V> SortedMap<K,V> checkedSortedMap(SortedMap<K, V> m, |
2928 |
Class<K> keyType, |
2929 |
Class<V> valueType) { |
2930 |
return new CheckedSortedMap<K,V>(m, keyType, valueType); |
2931 |
} |
2932 |
|
2933 |
/** |
2934 |
* @serial include |
2935 |
*/ |
2936 |
static class CheckedSortedMap<K,V> extends CheckedMap<K,V> |
2937 |
implements SortedMap<K,V>, Serializable |
2938 |
{ |
2939 |
private static final long serialVersionUID = 1599671320688067438L; |
2940 |
|
2941 |
private final SortedMap<K, V> sm; |
2942 |
|
2943 |
CheckedSortedMap(SortedMap<K, V> m, |
2944 |
Class<K> keyType, Class<V> valueType) { |
2945 |
super(m, keyType, valueType); |
2946 |
sm = m; |
2947 |
} |
2948 |
|
2949 |
public Comparator<? super K> comparator() { return sm.comparator(); } |
2950 |
public K firstKey() { return sm.firstKey(); } |
2951 |
public K lastKey() { return sm.lastKey(); } |
2952 |
|
2953 |
public SortedMap<K,V> subMap(K fromKey, K toKey) { |
2954 |
return checkedSortedMap(sm.subMap(fromKey, toKey), |
2955 |
keyType, valueType); |
2956 |
} |
2957 |
public SortedMap<K,V> headMap(K toKey) { |
2958 |
return checkedSortedMap(sm.headMap(toKey), keyType, valueType); |
2959 |
} |
2960 |
public SortedMap<K,V> tailMap(K fromKey) { |
2961 |
return checkedSortedMap(sm.tailMap(fromKey), keyType, valueType); |
2962 |
} |
2963 |
} |
2964 |
|
2965 |
// Empty collections |
2966 |
|
2967 |
/** |
2968 |
* Returns an iterator that has no elements. More precisely, |
2969 |
* |
2970 |
* <ul compact> |
2971 |
* |
2972 |
* <li>{@link Iterator#hasNext hasNext} always returns {@code |
2973 |
* false}. |
2974 |
* |
2975 |
* <li>{@link Iterator#next next} always throws {@link |
2976 |
* NoSuchElementException}. |
2977 |
* |
2978 |
* <li>{@link Iterator#remove remove} always throws {@link |
2979 |
* IllegalStateException}. |
2980 |
* |
2981 |
* </ul> |
2982 |
* |
2983 |
* <p>Implementations of this method are permitted, but not |
2984 |
* required, to return the same object from multiple invocations. |
2985 |
* |
2986 |
* @return an empty iterator |
2987 |
* @since 1.7 |
2988 |
*/ |
2989 |
@SuppressWarnings("unchecked") |
2990 |
public static <T> Iterator<T> emptyIterator() { |
2991 |
return (Iterator<T>) EmptyIterator.EMPTY_ITERATOR; |
2992 |
} |
2993 |
|
2994 |
private static class EmptyIterator<E> implements Iterator<E> { |
2995 |
static final EmptyIterator<Object> EMPTY_ITERATOR |
2996 |
= new EmptyIterator<Object>(); |
2997 |
|
2998 |
public boolean hasNext() { return false; } |
2999 |
public E next() { throw new NoSuchElementException(); } |
3000 |
public void remove() { throw new IllegalStateException(); } |
3001 |
} |
3002 |
|
3003 |
/** |
3004 |
* Returns a list iterator that has no elements. More precisely, |
3005 |
* |
3006 |
* <ul compact> |
3007 |
* |
3008 |
* <li>{@link Iterator#hasNext hasNext} and {@link |
3009 |
* ListIterator#hasPrevious hasPrevious} always return {@code |
3010 |
* false}. |
3011 |
* |
3012 |
* <li>{@link Iterator#next next} and {@link ListIterator#previous |
3013 |
* previous} always throw {@link NoSuchElementException}. |
3014 |
* |
3015 |
* <li>{@link Iterator#remove remove} and {@link ListIterator#set |
3016 |
* set} always throw {@link IllegalStateException}. |
3017 |
* |
3018 |
* <li>{@link ListIterator#add add} always throws {@link |
3019 |
* UnsupportedOperationException}. |
3020 |
* |
3021 |
* <li>{@link ListIterator#nextIndex nextIndex} always returns |
3022 |
* {@code 0} . |
3023 |
* |
3024 |
* <li>{@link ListIterator#previousIndex previousIndex} always |
3025 |
* returns {@code -1}. |
3026 |
* |
3027 |
* </ul> |
3028 |
* |
3029 |
* <p>Implementations of this method are permitted, but not |
3030 |
* required, to return the same object from multiple invocations. |
3031 |
* |
3032 |
* @return an empty list iterator |
3033 |
* @since 1.7 |
3034 |
*/ |
3035 |
@SuppressWarnings("unchecked") |
3036 |
public static <T> ListIterator<T> emptyListIterator() { |
3037 |
return (ListIterator<T>) EmptyListIterator.EMPTY_ITERATOR; |
3038 |
} |
3039 |
|
3040 |
private static class EmptyListIterator<E> |
3041 |
extends EmptyIterator<E> |
3042 |
implements ListIterator<E> |
3043 |
{ |
3044 |
static final EmptyListIterator<Object> EMPTY_ITERATOR |
3045 |
= new EmptyListIterator<Object>(); |
3046 |
|
3047 |
public boolean hasPrevious() { return false; } |
3048 |
public E previous() { throw new NoSuchElementException(); } |
3049 |
public int nextIndex() { return 0; } |
3050 |
public int previousIndex() { return -1; } |
3051 |
public void set(E e) { throw new IllegalStateException(); } |
3052 |
public void add(E e) { throw new UnsupportedOperationException(); } |
3053 |
} |
3054 |
|
3055 |
/** |
3056 |
* Returns an enumeration that has no elements. More precisely, |
3057 |
* |
3058 |
* <ul compact> |
3059 |
* |
3060 |
* <li>{@link Enumeration#hasMoreElements hasMoreElements} always |
3061 |
* returns {@code false}. |
3062 |
* |
3063 |
* <li> {@link Enumeration#nextElement nextElement} always throws |
3064 |
* {@link NoSuchElementException}. |
3065 |
* |
3066 |
* </ul> |
3067 |
* |
3068 |
* <p>Implementations of this method are permitted, but not |
3069 |
* required, to return the same object from multiple invocations. |
3070 |
* |
3071 |
* @return an empty enumeration |
3072 |
* @since 1.7 |
3073 |
*/ |
3074 |
@SuppressWarnings("unchecked") |
3075 |
public static <T> Enumeration<T> emptyEnumeration() { |
3076 |
return (Enumeration<T>) EmptyEnumeration.EMPTY_ENUMERATION; |
3077 |
} |
3078 |
|
3079 |
private static class EmptyEnumeration<E> implements Enumeration<E> { |
3080 |
static final EmptyEnumeration<Object> EMPTY_ENUMERATION |
3081 |
= new EmptyEnumeration<Object>(); |
3082 |
|
3083 |
public boolean hasMoreElements() { return false; } |
3084 |
public E nextElement() { throw new NoSuchElementException(); } |
3085 |
} |
3086 |
|
3087 |
/** |
3088 |
* The empty set (immutable). This set is serializable. |
3089 |
* |
3090 |
* @see #emptySet() |
3091 |
*/ |
3092 |
@SuppressWarnings("unchecked") |
3093 |
public static final Set EMPTY_SET = new EmptySet<Object>(); |
3094 |
|
3095 |
/** |
3096 |
* Returns the empty set (immutable). This set is serializable. |
3097 |
* Unlike the like-named field, this method is parameterized. |
3098 |
* |
3099 |
* <p>This example illustrates the type-safe way to obtain an empty set: |
3100 |
* <pre> |
3101 |
* Set<String> s = Collections.emptySet(); |
3102 |
* </pre> |
3103 |
* Implementation note: Implementations of this method need not |
3104 |
* create a separate <tt>Set</tt> object for each call. Using this |
3105 |
* method is likely to have comparable cost to using the like-named |
3106 |
* field. (Unlike this method, the field does not provide type safety.) |
3107 |
* |
3108 |
* @see #EMPTY_SET |
3109 |
* @since 1.5 |
3110 |
*/ |
3111 |
@SuppressWarnings("unchecked") |
3112 |
public static final <T> Set<T> emptySet() { |
3113 |
return (Set<T>) EMPTY_SET; |
3114 |
} |
3115 |
|
3116 |
/** |
3117 |
* @serial include |
3118 |
*/ |
3119 |
private static class EmptySet<E> |
3120 |
extends AbstractSet<E> |
3121 |
implements Serializable |
3122 |
{ |
3123 |
private static final long serialVersionUID = 1582296315990362920L; |
3124 |
|
3125 |
public Iterator<E> iterator() { return emptyIterator(); } |
3126 |
|
3127 |
public int size() {return 0;} |
3128 |
public boolean isEmpty() {return true;} |
3129 |
|
3130 |
public boolean contains(Object obj) {return false;} |
3131 |
public boolean containsAll(Collection<?> c) { return c.isEmpty(); } |
3132 |
|
3133 |
public Object[] toArray() { return new Object[0]; } |
3134 |
|
3135 |
public <T> T[] toArray(T[] a) { |
3136 |
if (a.length > 0) |
3137 |
a[0] = null; |
3138 |
return a; |
3139 |
} |
3140 |
|
3141 |
// Preserves singleton property |
3142 |
private Object readResolve() { |
3143 |
return EMPTY_SET; |
3144 |
} |
3145 |
} |
3146 |
|
3147 |
/** |
3148 |
* The empty list (immutable). This list is serializable. |
3149 |
* |
3150 |
* @see #emptyList() |
3151 |
*/ |
3152 |
@SuppressWarnings("unchecked") |
3153 |
public static final List EMPTY_LIST = new EmptyList<Object>(); |
3154 |
|
3155 |
/** |
3156 |
* Returns the empty list (immutable). This list is serializable. |
3157 |
* |
3158 |
* <p>This example illustrates the type-safe way to obtain an empty list: |
3159 |
* <pre> |
3160 |
* List<String> s = Collections.emptyList(); |
3161 |
* </pre> |
3162 |
* Implementation note: Implementations of this method need not |
3163 |
* create a separate <tt>List</tt> object for each call. Using this |
3164 |
* method is likely to have comparable cost to using the like-named |
3165 |
* field. (Unlike this method, the field does not provide type safety.) |
3166 |
* |
3167 |
* @see #EMPTY_LIST |
3168 |
* @since 1.5 |
3169 |
*/ |
3170 |
@SuppressWarnings("unchecked") |
3171 |
public static final <T> List<T> emptyList() { |
3172 |
return (List<T>) EMPTY_LIST; |
3173 |
} |
3174 |
|
3175 |
/** |
3176 |
* @serial include |
3177 |
*/ |
3178 |
private static class EmptyList<E> |
3179 |
extends AbstractList<E> |
3180 |
implements RandomAccess, Serializable { |
3181 |
private static final long serialVersionUID = 8842843931221139166L; |
3182 |
|
3183 |
public Iterator<E> iterator() { |
3184 |
return emptyIterator(); |
3185 |
} |
3186 |
public ListIterator<E> listIterator() { |
3187 |
return emptyListIterator(); |
3188 |
} |
3189 |
|
3190 |
public int size() {return 0;} |
3191 |
public boolean isEmpty() {return true;} |
3192 |
|
3193 |
public boolean contains(Object obj) {return false;} |
3194 |
public boolean containsAll(Collection<?> c) { return c.isEmpty(); } |
3195 |
|
3196 |
public Object[] toArray() { return new Object[0]; } |
3197 |
|
3198 |
public <T> T[] toArray(T[] a) { |
3199 |
if (a.length > 0) |
3200 |
a[0] = null; |
3201 |
return a; |
3202 |
} |
3203 |
|
3204 |
public E get(int index) { |
3205 |
throw new IndexOutOfBoundsException("Index: "+index); |
3206 |
} |
3207 |
|
3208 |
public boolean equals(Object o) { |
3209 |
return (o instanceof List) && ((List<?>)o).isEmpty(); |
3210 |
} |
3211 |
|
3212 |
public int hashCode() { return 1; } |
3213 |
|
3214 |
// Preserves singleton property |
3215 |
private Object readResolve() { |
3216 |
return EMPTY_LIST; |
3217 |
} |
3218 |
} |
3219 |
|
3220 |
/** |
3221 |
* The empty map (immutable). This map is serializable. |
3222 |
* |
3223 |
* @see #emptyMap() |
3224 |
* @since 1.3 |
3225 |
*/ |
3226 |
@SuppressWarnings("unchecked") |
3227 |
public static final Map EMPTY_MAP = new EmptyMap<Object,Object>(); |
3228 |
|
3229 |
/** |
3230 |
* Returns the empty map (immutable). This map is serializable. |
3231 |
* |
3232 |
* <p>This example illustrates the type-safe way to obtain an empty set: |
3233 |
* <pre> |
3234 |
* Map<String, Date> s = Collections.emptyMap(); |
3235 |
* </pre> |
3236 |
* Implementation note: Implementations of this method need not |
3237 |
* create a separate <tt>Map</tt> object for each call. Using this |
3238 |
* method is likely to have comparable cost to using the like-named |
3239 |
* field. (Unlike this method, the field does not provide type safety.) |
3240 |
* |
3241 |
* @see #EMPTY_MAP |
3242 |
* @since 1.5 |
3243 |
*/ |
3244 |
@SuppressWarnings("unchecked") |
3245 |
public static final <K,V> Map<K,V> emptyMap() { |
3246 |
return (Map<K,V>) EMPTY_MAP; |
3247 |
} |
3248 |
|
3249 |
/** |
3250 |
* @serial include |
3251 |
*/ |
3252 |
private static class EmptyMap<K,V> |
3253 |
extends AbstractMap<K,V> |
3254 |
implements Serializable |
3255 |
{ |
3256 |
private static final long serialVersionUID = 6428348081105594320L; |
3257 |
|
3258 |
public int size() {return 0;} |
3259 |
public boolean isEmpty() {return true;} |
3260 |
public boolean containsKey(Object key) {return false;} |
3261 |
public boolean containsValue(Object value) {return false;} |
3262 |
public V get(Object key) {return null;} |
3263 |
public Set<K> keySet() {return emptySet();} |
3264 |
public Collection<V> values() {return emptySet();} |
3265 |
public Set<Map.Entry<K,V>> entrySet() {return emptySet();} |
3266 |
|
3267 |
public boolean equals(Object o) { |
3268 |
return (o instanceof Map) && ((Map<?,?>)o).isEmpty(); |
3269 |
} |
3270 |
|
3271 |
public int hashCode() {return 0;} |
3272 |
|
3273 |
// Preserves singleton property |
3274 |
private Object readResolve() { |
3275 |
return EMPTY_MAP; |
3276 |
} |
3277 |
} |
3278 |
|
3279 |
// Singleton collections |
3280 |
|
3281 |
/** |
3282 |
* Returns an immutable set containing only the specified object. |
3283 |
* The returned set is serializable. |
3284 |
* |
3285 |
* @param o the sole object to be stored in the returned set. |
3286 |
* @return an immutable set containing only the specified object. |
3287 |
*/ |
3288 |
public static <T> Set<T> singleton(T o) { |
3289 |
return new SingletonSet<T>(o); |
3290 |
} |
3291 |
|
3292 |
static <E> Iterator<E> singletonIterator(final E e) { |
3293 |
return new Iterator<E>() { |
3294 |
private boolean hasNext = true; |
3295 |
public boolean hasNext() { |
3296 |
return hasNext; |
3297 |
} |
3298 |
public E next() { |
3299 |
if (hasNext) { |
3300 |
hasNext = false; |
3301 |
return e; |
3302 |
} |
3303 |
throw new NoSuchElementException(); |
3304 |
} |
3305 |
public void remove() { |
3306 |
throw new UnsupportedOperationException(); |
3307 |
} |
3308 |
}; |
3309 |
} |
3310 |
|
3311 |
/** |
3312 |
* @serial include |
3313 |
*/ |
3314 |
private static class SingletonSet<E> |
3315 |
extends AbstractSet<E> |
3316 |
implements Serializable |
3317 |
{ |
3318 |
private static final long serialVersionUID = 3193687207550431679L; |
3319 |
|
3320 |
private final E element; |
3321 |
|
3322 |
SingletonSet(E e) {element = e;} |
3323 |
|
3324 |
public Iterator<E> iterator() { |
3325 |
return singletonIterator(element); |
3326 |
} |
3327 |
|
3328 |
public int size() {return 1;} |
3329 |
|
3330 |
public boolean contains(Object o) {return eq(o, element);} |
3331 |
} |
3332 |
|
3333 |
/** |
3334 |
* Returns an immutable list containing only the specified object. |
3335 |
* The returned list is serializable. |
3336 |
* |
3337 |
* @param o the sole object to be stored in the returned list. |
3338 |
* @return an immutable list containing only the specified object. |
3339 |
* @since 1.3 |
3340 |
*/ |
3341 |
public static <T> List<T> singletonList(T o) { |
3342 |
return new SingletonList<T>(o); |
3343 |
} |
3344 |
|
3345 |
/** |
3346 |
* @serial include |
3347 |
*/ |
3348 |
private static class SingletonList<E> |
3349 |
extends AbstractList<E> |
3350 |
implements RandomAccess, Serializable { |
3351 |
|
3352 |
private static final long serialVersionUID = 3093736618740652951L; |
3353 |
|
3354 |
private final E element; |
3355 |
|
3356 |
SingletonList(E obj) {element = obj;} |
3357 |
|
3358 |
public Iterator<E> iterator() { |
3359 |
return singletonIterator(element); |
3360 |
} |
3361 |
|
3362 |
public int size() {return 1;} |
3363 |
|
3364 |
public boolean contains(Object obj) {return eq(obj, element);} |
3365 |
|
3366 |
public E get(int index) { |
3367 |
if (index != 0) |
3368 |
throw new IndexOutOfBoundsException("Index: "+index+", Size: 1"); |
3369 |
return element; |
3370 |
} |
3371 |
} |
3372 |
|
3373 |
/** |
3374 |
* Returns an immutable map, mapping only the specified key to the |
3375 |
* specified value. The returned map is serializable. |
3376 |
* |
3377 |
* @param key the sole key to be stored in the returned map. |
3378 |
* @param value the value to which the returned map maps <tt>key</tt>. |
3379 |
* @return an immutable map containing only the specified key-value |
3380 |
* mapping. |
3381 |
* @since 1.3 |
3382 |
*/ |
3383 |
public static <K,V> Map<K,V> singletonMap(K key, V value) { |
3384 |
return new SingletonMap<K,V>(key, value); |
3385 |
} |
3386 |
|
3387 |
/** |
3388 |
* @serial include |
3389 |
*/ |
3390 |
private static class SingletonMap<K,V> |
3391 |
extends AbstractMap<K,V> |
3392 |
implements Serializable { |
3393 |
private static final long serialVersionUID = -6979724477215052911L; |
3394 |
|
3395 |
private final K k; |
3396 |
private final V v; |
3397 |
|
3398 |
SingletonMap(K key, V value) { |
3399 |
k = key; |
3400 |
v = value; |
3401 |
} |
3402 |
|
3403 |
public int size() {return 1;} |
3404 |
|
3405 |
public boolean isEmpty() {return false;} |
3406 |
|
3407 |
public boolean containsKey(Object key) {return eq(key, k);} |
3408 |
|
3409 |
public boolean containsValue(Object value) {return eq(value, v);} |
3410 |
|
3411 |
public V get(Object key) {return (eq(key, k) ? v : null);} |
3412 |
|
3413 |
private transient Set<K> keySet = null; |
3414 |
private transient Set<Map.Entry<K,V>> entrySet = null; |
3415 |
private transient Collection<V> values = null; |
3416 |
|
3417 |
public Set<K> keySet() { |
3418 |
if (keySet==null) |
3419 |
keySet = singleton(k); |
3420 |
return keySet; |
3421 |
} |
3422 |
|
3423 |
public Set<Map.Entry<K,V>> entrySet() { |
3424 |
if (entrySet==null) |
3425 |
entrySet = Collections.<Map.Entry<K,V>>singleton( |
3426 |
new SimpleImmutableEntry<K,V>(k, v)); |
3427 |
return entrySet; |
3428 |
} |
3429 |
|
3430 |
public Collection<V> values() { |
3431 |
if (values==null) |
3432 |
values = singleton(v); |
3433 |
return values; |
3434 |
} |
3435 |
|
3436 |
} |
3437 |
|
3438 |
// Miscellaneous |
3439 |
|
3440 |
/** |
3441 |
* Returns an immutable list consisting of <tt>n</tt> copies of the |
3442 |
* specified object. The newly allocated data object is tiny (it contains |
3443 |
* a single reference to the data object). This method is useful in |
3444 |
* combination with the <tt>List.addAll</tt> method to grow lists. |
3445 |
* The returned list is serializable. |
3446 |
* |
3447 |
* @param n the number of elements in the returned list. |
3448 |
* @param o the element to appear repeatedly in the returned list. |
3449 |
* @return an immutable list consisting of <tt>n</tt> copies of the |
3450 |
* specified object. |
3451 |
* @throws IllegalArgumentException if {@code n < 0} |
3452 |
* @see List#addAll(Collection) |
3453 |
* @see List#addAll(int, Collection) |
3454 |
*/ |
3455 |
public static <T> List<T> nCopies(int n, T o) { |
3456 |
if (n < 0) |
3457 |
throw new IllegalArgumentException("List length = " + n); |
3458 |
return new CopiesList<T>(n, o); |
3459 |
} |
3460 |
|
3461 |
/** |
3462 |
* @serial include |
3463 |
*/ |
3464 |
private static class CopiesList<E> |
3465 |
extends AbstractList<E> |
3466 |
implements RandomAccess, Serializable |
3467 |
{ |
3468 |
private static final long serialVersionUID = 2739099268398711800L; |
3469 |
|
3470 |
final int n; |
3471 |
final E element; |
3472 |
|
3473 |
CopiesList(int n, E e) { |
3474 |
assert n >= 0; |
3475 |
this.n = n; |
3476 |
element = e; |
3477 |
} |
3478 |
|
3479 |
public int size() { |
3480 |
return n; |
3481 |
} |
3482 |
|
3483 |
public boolean contains(Object obj) { |
3484 |
return n != 0 && eq(obj, element); |
3485 |
} |
3486 |
|
3487 |
public int indexOf(Object o) { |
3488 |
return contains(o) ? 0 : -1; |
3489 |
} |
3490 |
|
3491 |
public int lastIndexOf(Object o) { |
3492 |
return contains(o) ? n - 1 : -1; |
3493 |
} |
3494 |
|
3495 |
public E get(int index) { |
3496 |
if (index < 0 || index >= n) |
3497 |
throw new IndexOutOfBoundsException("Index: "+index+ |
3498 |
", Size: "+n); |
3499 |
return element; |
3500 |
} |
3501 |
|
3502 |
public Object[] toArray() { |
3503 |
final Object[] a = new Object[n]; |
3504 |
if (element != null) |
3505 |
Arrays.fill(a, 0, n, element); |
3506 |
return a; |
3507 |
} |
3508 |
|
3509 |
public <T> T[] toArray(T[] a) { |
3510 |
final int n = this.n; |
3511 |
if (a.length < n) { |
3512 |
a = (T[])java.lang.reflect.Array |
3513 |
.newInstance(a.getClass().getComponentType(), n); |
3514 |
if (element != null) |
3515 |
Arrays.fill(a, 0, n, element); |
3516 |
} else { |
3517 |
Arrays.fill(a, 0, n, element); |
3518 |
if (a.length > n) |
3519 |
a[n] = null; |
3520 |
} |
3521 |
return a; |
3522 |
} |
3523 |
|
3524 |
public List<E> subList(int fromIndex, int toIndex) { |
3525 |
if (fromIndex < 0) |
3526 |
throw new IndexOutOfBoundsException("fromIndex = " + fromIndex); |
3527 |
if (toIndex > n) |
3528 |
throw new IndexOutOfBoundsException("toIndex = " + toIndex); |
3529 |
if (fromIndex > toIndex) |
3530 |
throw new IllegalArgumentException("fromIndex(" + fromIndex + |
3531 |
") > toIndex(" + toIndex + ")"); |
3532 |
return new CopiesList<E>(toIndex - fromIndex, element); |
3533 |
} |
3534 |
} |
3535 |
|
3536 |
/** |
3537 |
* Returns a comparator that imposes the reverse of the <i>natural |
3538 |
* ordering</i> on a collection of objects that implement the |
3539 |
* <tt>Comparable</tt> interface. (The natural ordering is the ordering |
3540 |
* imposed by the objects' own <tt>compareTo</tt> method.) This enables a |
3541 |
* simple idiom for sorting (or maintaining) collections (or arrays) of |
3542 |
* objects that implement the <tt>Comparable</tt> interface in |
3543 |
* reverse-natural-order. For example, suppose a is an array of |
3544 |
* strings. Then: <pre> |
3545 |
* Arrays.sort(a, Collections.reverseOrder()); |
3546 |
* </pre> sorts the array in reverse-lexicographic (alphabetical) order.<p> |
3547 |
* |
3548 |
* The returned comparator is serializable. |
3549 |
* |
3550 |
* @return a comparator that imposes the reverse of the <i>natural |
3551 |
* ordering</i> on a collection of objects that implement |
3552 |
* the <tt>Comparable</tt> interface. |
3553 |
* @see Comparable |
3554 |
*/ |
3555 |
public static <T> Comparator<T> reverseOrder() { |
3556 |
return (Comparator<T>) ReverseComparator.REVERSE_ORDER; |
3557 |
} |
3558 |
|
3559 |
/** |
3560 |
* @serial include |
3561 |
*/ |
3562 |
private static class ReverseComparator |
3563 |
implements Comparator<Comparable<Object>>, Serializable { |
3564 |
|
3565 |
private static final long serialVersionUID = 7207038068494060240L; |
3566 |
|
3567 |
static final ReverseComparator REVERSE_ORDER |
3568 |
= new ReverseComparator(); |
3569 |
|
3570 |
public int compare(Comparable<Object> c1, Comparable<Object> c2) { |
3571 |
return c2.compareTo(c1); |
3572 |
} |
3573 |
|
3574 |
private Object readResolve() { return reverseOrder(); } |
3575 |
} |
3576 |
|
3577 |
/** |
3578 |
* Returns a comparator that imposes the reverse ordering of the specified |
3579 |
* comparator. If the specified comparator is null, this method is |
3580 |
* equivalent to {@link #reverseOrder()} (in other words, it returns a |
3581 |
* comparator that imposes the reverse of the <i>natural ordering</i> on a |
3582 |
* collection of objects that implement the Comparable interface). |
3583 |
* |
3584 |
* <p>The returned comparator is serializable (assuming the specified |
3585 |
* comparator is also serializable or null). |
3586 |
* |
3587 |
* @return a comparator that imposes the reverse ordering of the |
3588 |
* specified comparator |
3589 |
* @since 1.5 |
3590 |
*/ |
3591 |
public static <T> Comparator<T> reverseOrder(Comparator<T> cmp) { |
3592 |
if (cmp == null) |
3593 |
return reverseOrder(); |
3594 |
|
3595 |
if (cmp instanceof ReverseComparator2) |
3596 |
return ((ReverseComparator2<T>)cmp).cmp; |
3597 |
|
3598 |
return new ReverseComparator2<T>(cmp); |
3599 |
} |
3600 |
|
3601 |
/** |
3602 |
* @serial include |
3603 |
*/ |
3604 |
private static class ReverseComparator2<T> implements Comparator<T>, |
3605 |
Serializable |
3606 |
{ |
3607 |
private static final long serialVersionUID = 4374092139857L; |
3608 |
|
3609 |
/** |
3610 |
* The comparator specified in the static factory. This will never |
3611 |
* be null, as the static factory returns a ReverseComparator |
3612 |
* instance if its argument is null. |
3613 |
* |
3614 |
* @serial |
3615 |
*/ |
3616 |
final Comparator<T> cmp; |
3617 |
|
3618 |
ReverseComparator2(Comparator<T> cmp) { |
3619 |
assert cmp != null; |
3620 |
this.cmp = cmp; |
3621 |
} |
3622 |
|
3623 |
public int compare(T t1, T t2) { |
3624 |
return cmp.compare(t2, t1); |
3625 |
} |
3626 |
|
3627 |
public boolean equals(Object o) { |
3628 |
return (o == this) || |
3629 |
(o instanceof ReverseComparator2 && |
3630 |
cmp.equals(((ReverseComparator2)o).cmp)); |
3631 |
} |
3632 |
|
3633 |
public int hashCode() { |
3634 |
return cmp.hashCode() ^ Integer.MIN_VALUE; |
3635 |
} |
3636 |
} |
3637 |
|
3638 |
/** |
3639 |
* Returns an enumeration over the specified collection. This provides |
3640 |
* interoperability with legacy APIs that require an enumeration |
3641 |
* as input. |
3642 |
* |
3643 |
* @param c the collection for which an enumeration is to be returned. |
3644 |
* @return an enumeration over the specified collection. |
3645 |
* @see Enumeration |
3646 |
*/ |
3647 |
public static <T> Enumeration<T> enumeration(final Collection<T> c) { |
3648 |
return new Enumeration<T>() { |
3649 |
private final Iterator<T> i = c.iterator(); |
3650 |
|
3651 |
public boolean hasMoreElements() { |
3652 |
return i.hasNext(); |
3653 |
} |
3654 |
|
3655 |
public T nextElement() { |
3656 |
return i.next(); |
3657 |
} |
3658 |
}; |
3659 |
} |
3660 |
|
3661 |
/** |
3662 |
* Returns an array list containing the elements returned by the |
3663 |
* specified enumeration in the order they are returned by the |
3664 |
* enumeration. This method provides interoperability between |
3665 |
* legacy APIs that return enumerations and new APIs that require |
3666 |
* collections. |
3667 |
* |
3668 |
* @param e enumeration providing elements for the returned |
3669 |
* array list |
3670 |
* @return an array list containing the elements returned |
3671 |
* by the specified enumeration. |
3672 |
* @since 1.4 |
3673 |
* @see Enumeration |
3674 |
* @see ArrayList |
3675 |
*/ |
3676 |
public static <T> ArrayList<T> list(Enumeration<T> e) { |
3677 |
ArrayList<T> l = new ArrayList<T>(); |
3678 |
while (e.hasMoreElements()) |
3679 |
l.add(e.nextElement()); |
3680 |
return l; |
3681 |
} |
3682 |
|
3683 |
/** |
3684 |
* Returns true if the specified arguments are equal, or both null. |
3685 |
*/ |
3686 |
static boolean eq(Object o1, Object o2) { |
3687 |
return o1==null ? o2==null : o1.equals(o2); |
3688 |
} |
3689 |
|
3690 |
/** |
3691 |
* Returns the number of elements in the specified collection equal to the |
3692 |
* specified object. More formally, returns the number of elements |
3693 |
* <tt>e</tt> in the collection such that |
3694 |
* <tt>(o == null ? e == null : o.equals(e))</tt>. |
3695 |
* |
3696 |
* @param c the collection in which to determine the frequency |
3697 |
* of <tt>o</tt> |
3698 |
* @param o the object whose frequency is to be determined |
3699 |
* @throws NullPointerException if <tt>c</tt> is null |
3700 |
* @since 1.5 |
3701 |
*/ |
3702 |
public static int frequency(Collection<?> c, Object o) { |
3703 |
int result = 0; |
3704 |
if (o == null) { |
3705 |
for (Object e : c) |
3706 |
if (e == null) |
3707 |
result++; |
3708 |
} else { |
3709 |
for (Object e : c) |
3710 |
if (o.equals(e)) |
3711 |
result++; |
3712 |
} |
3713 |
return result; |
3714 |
} |
3715 |
|
3716 |
/** |
3717 |
* Returns <tt>true</tt> if the two specified collections have no |
3718 |
* elements in common. |
3719 |
* |
3720 |
* <p>Care must be exercised if this method is used on collections that |
3721 |
* do not comply with the general contract for <tt>Collection</tt>. |
3722 |
* Implementations may elect to iterate over either collection and test |
3723 |
* for containment in the other collection (or to perform any equivalent |
3724 |
* computation). If either collection uses a nonstandard equality test |
3725 |
* (as does a {@link SortedSet} whose ordering is not <i>compatible with |
3726 |
* equals</i>, or the key set of an {@link IdentityHashMap}), both |
3727 |
* collections must use the same nonstandard equality test, or the |
3728 |
* result of this method is undefined. |
3729 |
* |
3730 |
* <p>Note that it is permissible to pass the same collection in both |
3731 |
* parameters, in which case the method will return true if and only if |
3732 |
* the collection is empty. |
3733 |
* |
3734 |
* @param c1 a collection |
3735 |
* @param c2 a collection |
3736 |
* @throws NullPointerException if either collection is null |
3737 |
* @since 1.5 |
3738 |
*/ |
3739 |
public static boolean disjoint(Collection<?> c1, Collection<?> c2) { |
3740 |
/* |
3741 |
* We're going to iterate through c1 and test for inclusion in c2. |
3742 |
* If c1 is a Set and c2 isn't, swap the collections. Otherwise, |
3743 |
* place the shorter collection in c1. Hopefully this heuristic |
3744 |
* will minimize the cost of the operation. |
3745 |
*/ |
3746 |
if ((c1 instanceof Set) && !(c2 instanceof Set) || |
3747 |
(c1.size() > c2.size())) { |
3748 |
Collection<?> tmp = c1; |
3749 |
c1 = c2; |
3750 |
c2 = tmp; |
3751 |
} |
3752 |
|
3753 |
for (Object e : c1) |
3754 |
if (c2.contains(e)) |
3755 |
return false; |
3756 |
return true; |
3757 |
} |
3758 |
|
3759 |
/** |
3760 |
* Adds all of the specified elements to the specified collection. |
3761 |
* Elements to be added may be specified individually or as an array. |
3762 |
* The behavior of this convenience method is identical to that of |
3763 |
* <tt>c.addAll(Arrays.asList(elements))</tt>, but this method is likely |
3764 |
* to run significantly faster under most implementations. |
3765 |
* |
3766 |
* <p>When elements are specified individually, this method provides a |
3767 |
* convenient way to add a few elements to an existing collection: |
3768 |
* <pre> |
3769 |
* Collections.addAll(flavors, "Peaches 'n Plutonium", "Rocky Racoon"); |
3770 |
* </pre> |
3771 |
* |
3772 |
* @param c the collection into which <tt>elements</tt> are to be inserted |
3773 |
* @param elements the elements to insert into <tt>c</tt> |
3774 |
* @return <tt>true</tt> if the collection changed as a result of the call |
3775 |
* @throws UnsupportedOperationException if <tt>c</tt> does not support |
3776 |
* the <tt>add</tt> operation |
3777 |
* @throws NullPointerException if <tt>elements</tt> contains one or more |
3778 |
* null values and <tt>c</tt> does not permit null elements, or |
3779 |
* if <tt>c</tt> or <tt>elements</tt> are <tt>null</tt> |
3780 |
* @throws IllegalArgumentException if some property of a value in |
3781 |
* <tt>elements</tt> prevents it from being added to <tt>c</tt> |
3782 |
* @see Collection#addAll(Collection) |
3783 |
* @since 1.5 |
3784 |
*/ |
3785 |
public static <T> boolean addAll(Collection<? super T> c, T... elements) { |
3786 |
boolean result = false; |
3787 |
for (T element : elements) |
3788 |
result |= c.add(element); |
3789 |
return result; |
3790 |
} |
3791 |
|
3792 |
/** |
3793 |
* Returns a set backed by the specified map. The resulting set displays |
3794 |
* the same ordering, concurrency, and performance characteristics as the |
3795 |
* backing map. In essence, this factory method provides a {@link Set} |
3796 |
* implementation corresponding to any {@link Map} implementation. There |
3797 |
* is no need to use this method on a {@link Map} implementation that |
3798 |
* already has a corresponding {@link Set} implementation (such as {@link |
3799 |
* HashMap} or {@link TreeMap}). |
3800 |
* |
3801 |
* <p>Each method invocation on the set returned by this method results in |
3802 |
* exactly one method invocation on the backing map or its <tt>keySet</tt> |
3803 |
* view, with one exception. The <tt>addAll</tt> method is implemented |
3804 |
* as a sequence of <tt>put</tt> invocations on the backing map. |
3805 |
* |
3806 |
* <p>The specified map must be empty at the time this method is invoked, |
3807 |
* and should not be accessed directly after this method returns. These |
3808 |
* conditions are ensured if the map is created empty, passed directly |
3809 |
* to this method, and no reference to the map is retained, as illustrated |
3810 |
* in the following code fragment: |
3811 |
* <pre> |
3812 |
* Set<Object> weakHashSet = Collections.newSetFromMap( |
3813 |
* new WeakHashMap<Object, Boolean>()); |
3814 |
* </pre> |
3815 |
* |
3816 |
* @param map the backing map |
3817 |
* @return the set backed by the map |
3818 |
* @throws IllegalArgumentException if <tt>map</tt> is not empty |
3819 |
* @since 1.6 |
3820 |
*/ |
3821 |
public static <E> Set<E> newSetFromMap(Map<E, Boolean> map) { |
3822 |
return new SetFromMap<E>(map); |
3823 |
} |
3824 |
|
3825 |
/** |
3826 |
* @serial include |
3827 |
*/ |
3828 |
private static class SetFromMap<E> extends AbstractSet<E> |
3829 |
implements Set<E>, Serializable |
3830 |
{ |
3831 |
private final Map<E, Boolean> m; // The backing map |
3832 |
private transient Set<E> s; // Its keySet |
3833 |
|
3834 |
SetFromMap(Map<E, Boolean> map) { |
3835 |
if (!map.isEmpty()) |
3836 |
throw new IllegalArgumentException("Map is non-empty"); |
3837 |
m = map; |
3838 |
s = map.keySet(); |
3839 |
} |
3840 |
|
3841 |
public void clear() { m.clear(); } |
3842 |
public int size() { return m.size(); } |
3843 |
public boolean isEmpty() { return m.isEmpty(); } |
3844 |
public boolean contains(Object o) { return m.containsKey(o); } |
3845 |
public boolean remove(Object o) { return m.remove(o) != null; } |
3846 |
public boolean add(E e) { return m.put(e, Boolean.TRUE) == null; } |
3847 |
public Iterator<E> iterator() { return s.iterator(); } |
3848 |
public Object[] toArray() { return s.toArray(); } |
3849 |
public <T> T[] toArray(T[] a) { return s.toArray(a); } |
3850 |
public String toString() { return s.toString(); } |
3851 |
public int hashCode() { return s.hashCode(); } |
3852 |
public boolean equals(Object o) { return o == this || s.equals(o); } |
3853 |
public boolean containsAll(Collection<?> c) {return s.containsAll(c);} |
3854 |
public boolean removeAll(Collection<?> c) {return s.removeAll(c);} |
3855 |
public boolean retainAll(Collection<?> c) {return s.retainAll(c);} |
3856 |
// addAll is the only inherited implementation |
3857 |
|
3858 |
private static final long serialVersionUID = 2454657854757543876L; |
3859 |
|
3860 |
private void readObject(java.io.ObjectInputStream stream) |
3861 |
throws IOException, ClassNotFoundException |
3862 |
{ |
3863 |
stream.defaultReadObject(); |
3864 |
s = m.keySet(); |
3865 |
} |
3866 |
} |
3867 |
|
3868 |
/** |
3869 |
* Returns a view of a {@link Deque} as a Last-in-first-out (Lifo) |
3870 |
* {@link Queue}. Method <tt>add</tt> is mapped to <tt>push</tt>, |
3871 |
* <tt>remove</tt> is mapped to <tt>pop</tt> and so on. This |
3872 |
* view can be useful when you would like to use a method |
3873 |
* requiring a <tt>Queue</tt> but you need Lifo ordering. |
3874 |
* |
3875 |
* <p>Each method invocation on the queue returned by this method |
3876 |
* results in exactly one method invocation on the backing deque, with |
3877 |
* one exception. The {@link Queue#addAll addAll} method is |
3878 |
* implemented as a sequence of {@link Deque#addFirst addFirst} |
3879 |
* invocations on the backing deque. |
3880 |
* |
3881 |
* @param deque the deque |
3882 |
* @return the queue |
3883 |
* @since 1.6 |
3884 |
*/ |
3885 |
public static <T> Queue<T> asLifoQueue(Deque<T> deque) { |
3886 |
return new AsLIFOQueue<T>(deque); |
3887 |
} |
3888 |
|
3889 |
/** |
3890 |
* @serial include |
3891 |
*/ |
3892 |
static class AsLIFOQueue<E> extends AbstractQueue<E> |
3893 |
implements Queue<E>, Serializable { |
3894 |
private static final long serialVersionUID = 1802017725587941708L; |
3895 |
private final Deque<E> q; |
3896 |
AsLIFOQueue(Deque<E> q) { this.q = q; } |
3897 |
public boolean add(E e) { q.addFirst(e); return true; } |
3898 |
public boolean offer(E e) { return q.offerFirst(e); } |
3899 |
public E poll() { return q.pollFirst(); } |
3900 |
public E remove() { return q.removeFirst(); } |
3901 |
public E peek() { return q.peekFirst(); } |
3902 |
public E element() { return q.getFirst(); } |
3903 |
public void clear() { q.clear(); } |
3904 |
public int size() { return q.size(); } |
3905 |
public boolean isEmpty() { return q.isEmpty(); } |
3906 |
public boolean contains(Object o) { return q.contains(o); } |
3907 |
public boolean remove(Object o) { return q.remove(o); } |
3908 |
public Iterator<E> iterator() { return q.iterator(); } |
3909 |
public Object[] toArray() { return q.toArray(); } |
3910 |
public <T> T[] toArray(T[] a) { return q.toArray(a); } |
3911 |
public String toString() { return q.toString(); } |
3912 |
public boolean containsAll(Collection<?> c) {return q.containsAll(c);} |
3913 |
public boolean removeAll(Collection<?> c) {return q.removeAll(c);} |
3914 |
public boolean retainAll(Collection<?> c) {return q.retainAll(c);} |
3915 |
// We use inherited addAll; forwarding addAll would be wrong |
3916 |
} |
3917 |
} |