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/* |
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* %W% %E% |
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* Copyright 1998-2006 Sun Microsystems, Inc. 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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* Copyright 2005 Sun Microsystems, Inc. All rights reserved. |
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* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. |
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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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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* CA 95054 USA or visit www.sun.com if you need additional information or |
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* have any questions. |
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*/ |
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package java.util; |
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* time, depending on which constructor is used. |
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* |
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* <p>This implementation provides guaranteed log(n) time cost for the basic |
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* operations (<tt>add</tt>, <tt>remove</tt> and <tt>contains</tt>). |
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* operations ({@code add}, {@code remove} and {@code contains}). |
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* |
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* <p>Note that the ordering maintained by a set (whether or not an explicit |
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* comparator is provided) must be <i>consistent with equals</i> if it is to |
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* correctly implement the <tt>Set</tt> interface. (See <tt>Comparable</tt> |
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* or <tt>Comparator</tt> for a precise definition of <i>consistent with |
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* equals</i>.) This is so because the <tt>Set</tt> interface is defined in |
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* terms of the <tt>equals</tt> operation, but a <tt>TreeSet</tt> instance |
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* performs all element comparisons using its <tt>compareTo</tt> (or |
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* <tt>compare</tt>) method, so two elements that are deemed equal by this method |
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* correctly implement the {@code Set} interface. (See {@code Comparable} |
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* or {@code Comparator} for a precise definition of <i>consistent with |
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* equals</i>.) This is so because the {@code Set} interface is defined in |
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* terms of the {@code equals} operation, but a {@code TreeSet} instance |
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* performs all element comparisons using its {@code compareTo} (or |
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* {@code compare}) method, so two elements that are deemed equal by this method |
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* are, from the standpoint of the set, equal. The behavior of a set |
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* <i>is</i> well-defined even if its ordering is inconsistent with equals; it |
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* just fails to obey the general contract of the <tt>Set</tt> interface. |
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* just fails to obey the general contract of the {@code Set} interface. |
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* |
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* <p><b>Note that this implementation is not synchronized.</b> If multiple |
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* threads access a set concurrently, and at least one of the threads modifies |
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* the set, it <i>must</i> be synchronized externally. This is typically |
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* accomplished by synchronizing on some object that naturally encapsulates |
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* the set. If no such object exists, the set should be "wrapped" using the |
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* <tt>Collections.synchronizedSet</tt> method. This is best done at creation |
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* time, to prevent accidental unsynchronized access to the set: <pre> |
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* SortedSet s = Collections.synchronizedSortedSet(new TreeSet(...)); |
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* </pre> |
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* <p><strong>Note that this implementation is not synchronized.</strong> |
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* If multiple threads access a tree set concurrently, and at least one |
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* of the threads modifies the set, it <i>must</i> be synchronized |
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* externally. This is typically accomplished by synchronizing on some |
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* object that naturally encapsulates the set. |
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* If no such object exists, the set should be "wrapped" using the |
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* {@link Collections#synchronizedSortedSet Collections.synchronizedSortedSet} |
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* method. This is best done at creation time, to prevent accidental |
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* unsynchronized access to the set: <pre> |
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* SortedSet s = Collections.synchronizedSortedSet(new TreeSet(...));</pre> |
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* |
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* <p>The iterators returned by this class's <tt>iterator</tt> method are |
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* <p>The iterators returned by this class's {@code iterator} method are |
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* <i>fail-fast</i>: if the set is modified at any time after the iterator is |
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* created, in any way except through the iterator's own <tt>remove</tt> |
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* created, in any way except through the iterator's own {@code remove} |
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* method, the iterator will throw a {@link ConcurrentModificationException}. |
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* Thus, in the face of concurrent modification, the iterator fails quickly |
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* and cleanly, rather than risking arbitrary, non-deterministic behavior at |
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* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed |
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* as it is, generally speaking, impossible to make any hard guarantees in the |
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* presence of unsynchronized concurrent modification. Fail-fast iterators |
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* throw <tt>ConcurrentModificationException</tt> on a best-effort basis. |
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* throw {@code ConcurrentModificationException} on a best-effort basis. |
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* Therefore, it would be wrong to write a program that depended on this |
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* exception for its correctness: <i>the fail-fast behavior of iterators |
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* should be used only to detect bugs.</i> |
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* |
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* <p>This class is a member of the |
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* <a href="{@docRoot}/../guide/collections/index.html"> |
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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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* @param <E> the type of elements maintained by this set |
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* @see HashSet |
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* @see Comparable |
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* @see Comparator |
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* @see Collections#synchronizedSortedSet(SortedSet) |
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* @see TreeMap |
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* @since 1.2 |
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*/ |
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|
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public class TreeSet<E> |
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extends AbstractSet<E> |
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public class TreeSet<E> extends AbstractSet<E> |
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implements NavigableSet<E>, Cloneable, java.io.Serializable |
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{ |
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private transient NavigableMap<E,Object> m; // The backing Map |
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/** |
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* The backing map. |
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*/ |
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private transient NavigableMap<E,Object> m; |
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|
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// Dummy value to associate with an Object in the backing Map |
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private static final Object PRESENT = new Object(); |
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/** |
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* Constructs a set backed by the specified navigable map. |
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*/ |
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private TreeSet(NavigableMap<E,Object> m) { |
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TreeSet(NavigableMap<E,Object> m) { |
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this.m = m; |
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} |
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|
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* natural ordering of its elements. All elements inserted into |
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* the set must implement the {@link Comparable} interface. |
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* Furthermore, all such elements must be <i>mutually |
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* comparable</i>: <tt>e1.compareTo(e2)</tt> must not throw a |
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* <tt>ClassCastException</tt> for any elements <tt>e1</tt> and |
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* <tt>e2</tt> in the set. If the user attempts to add an element |
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* comparable</i>: {@code e1.compareTo(e2)} must not throw a |
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* {@code ClassCastException} for any elements {@code e1} and |
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* {@code e2} in the set. If the user attempts to add an element |
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* to the set that violates this constraint (for example, the user |
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* attempts to add a string element to a set whose elements are |
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* integers), the <tt>add(Object)</tt> call will throw a |
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* <tt>ClassCastException</tt>. |
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* integers), the {@code add} call will throw a |
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* {@code ClassCastException}. |
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*/ |
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public TreeSet() { |
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this(new TreeMap<E,Object>()); |
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/** |
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* Constructs a new, empty tree set, sorted according to the specified |
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* comparator. All elements inserted into the set must be <i>mutually |
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* comparable</i> by the specified comparator: <tt>comparator.compare(e1, |
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* e2)</tt> must not throw a <tt>ClassCastException</tt> for any elements |
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* <tt>e1</tt> and <tt>e2</tt> in the set. If the user attempts to add |
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* comparable</i> by the specified comparator: {@code comparator.compare(e1, |
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* e2)} must not throw a {@code ClassCastException} for any elements |
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* {@code e1} and {@code e2} in the set. If the user attempts to add |
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* an element to the set that violates this constraint, the |
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* <tt>add(Object)</tt> call will throw a <tt>ClassCastException</tt>. |
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* {@code add} call will throw a {@code ClassCastException}. |
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* |
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* @param comparator the comparator that will be used to order this set. |
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* If <tt>null</tt>, the {@linkplain Comparable natural |
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* If {@code null}, the {@linkplain Comparable natural |
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* ordering} of the elements will be used. |
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*/ |
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public TreeSet(Comparator<? super E> comparator) { |
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* collection, sorted according to the <i>natural ordering</i> of its |
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* elements. All elements inserted into the set must implement the |
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* {@link Comparable} interface. Furthermore, all such elements must be |
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* <i>mutually comparable</i>: <tt>e1.compareTo(e2)</tt> must not throw a |
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* <tt>ClassCastException</tt> for any elements <tt>e1</tt> and |
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* <tt>e2</tt> in the set. |
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* <i>mutually comparable</i>: {@code e1.compareTo(e2)} must not throw a |
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* {@code ClassCastException} for any elements {@code e1} and |
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* {@code e2} in the set. |
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* |
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* @param c collection whose elements will comprise the new set |
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* @throws ClassCastException if the elements in <tt>c</tt> are |
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* @throws ClassCastException if the elements in {@code c} are |
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* not {@link Comparable}, or are not mutually comparable |
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* @throws NullPointerException if the specified collection is null |
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*/ |
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* @return an iterator over the elements in this set in ascending order |
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*/ |
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public Iterator<E> iterator() { |
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return m.keySet().iterator(); |
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return m.navigableKeySet().iterator(); |
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} |
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/** |
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* Returns an iterator over the elements in this set in descending order. |
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* |
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* @return an iterator over the elements in this set in descending order |
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* @since 1.6 |
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*/ |
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public Iterator<E> descendingIterator() { |
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return m.descendingKeySet().iterator(); |
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} |
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/** |
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* @since 1.6 |
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*/ |
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public NavigableSet<E> descendingSet() { |
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return new TreeSet(m.descendingMap()); |
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} |
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|
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/** |
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* Returns the number of elements in this set (its cardinality). |
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* |
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* @return the number of elements in this set (its cardinality) |
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} |
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/** |
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* Returns <tt>true</tt> if this set contains no elements. |
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* Returns {@code true} if this set contains no elements. |
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* |
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* @return <tt>true</tt> if this set contains no elements |
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* @return {@code true} if this set contains no elements |
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*/ |
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public boolean isEmpty() { |
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return m.isEmpty(); |
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} |
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|
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/** |
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* Returns <tt>true</tt> if this set contains the specified element. |
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* Returns {@code true} if this set contains the specified element. |
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* More formally, returns {@code true} if and only if this set |
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* contains an element {@code e} such that |
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* <tt>(o==null ? e==null : o.equals(e))</tt>. |
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* |
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* @param o the object to be checked for containment in this set |
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* @return <tt>true</tt> if this set contains the specified element |
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* @param o object to be checked for containment in this set |
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* @return {@code true} if this set contains the specified element |
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* @throws ClassCastException if the specified object cannot be compared |
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* with the elements currently in the set |
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* @throws NullPointerException if the specified element is null |
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|
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/** |
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* Adds the specified element to this set if it is not already present. |
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* More formally, adds the specified element {@code e} to this set if |
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* the set contains no element {@code e2} such that |
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* <tt>(e==null ? e2==null : e.equals(e2))</tt>. |
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* If this set already contains the element, the call leaves the set |
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* unchanged and returns {@code false}. |
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* |
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* @param e element to be added to this set |
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* @return <tt>true</tt> if the set did not already contain the specified |
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* @return {@code true} if this set did not already contain the specified |
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* element |
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* @throws ClassCastException if the specified object cannot be compared |
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* with the elements currently in the set |
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* with the elements currently in this set |
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* @throws NullPointerException if the specified element is null |
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* and this set uses natural ordering, or its comparator |
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* does not permit null elements |
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|
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/** |
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* Removes the specified element from this set if it is present. |
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* More formally, removes an element {@code e} such that |
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* <tt>(o==null ? e==null : o.equals(e))</tt>, |
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* if this set contains such an element. Returns {@code true} if |
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* this set contained the element (or equivalently, if this set |
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* changed as a result of the call). (This set will not contain the |
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* element once the call returns.) |
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* |
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* @param o object to be removed from this set, if present |
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* @return <tt>true</tt> if the set contained the specified element |
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* @return {@code true} if this set contained the specified element |
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* @throws ClassCastException if the specified object cannot be compared |
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* with the elements currently in the set |
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* with the elements currently in this set |
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* @throws NullPointerException if the specified element is null |
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* and this set uses natural ordering, or its comparator |
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* does not permit null elements |
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* Adds all of the elements in the specified collection to this set. |
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* |
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* @param c collection containing elements to be added to this set |
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* @return <tt>true</tt> if this set changed as a result of the call |
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* @return {@code true} if this set changed as a result of the call |
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* @throws ClassCastException if the elements provided cannot be compared |
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* with the elements currently in the set |
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* @throws NullPointerException if the specified collection is null or |
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|
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/** |
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* @throws ClassCastException {@inheritDoc} |
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* @throws NullPointerException if <tt>fromElement</tt> or |
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* <tt>toElement</tt> is null and this set uses natural ordering, |
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* or its comparator does not permit null elements |
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* @throws NullPointerException if {@code fromElement} or {@code toElement} |
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* is null and this set uses natural ordering, or its comparator |
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* does not permit null elements |
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* @throws IllegalArgumentException {@inheritDoc} |
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* @since 1.6 |
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*/ |
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public NavigableSet<E> navigableSubSet(E fromElement, E toElement) { |
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return new TreeSet<E>(m.navigableSubMap(fromElement, toElement)); |
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public NavigableSet<E> subSet(E fromElement, boolean fromInclusive, |
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E toElement, boolean toInclusive) { |
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return new TreeSet<E>(m.subMap(fromElement, fromInclusive, |
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toElement, toInclusive)); |
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} |
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|
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/** |
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* @throws ClassCastException {@inheritDoc} |
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* @throws NullPointerException if <tt>toElement</tt> is null and |
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* @throws NullPointerException if {@code toElement} is null and |
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* this set uses natural ordering, or its comparator does |
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* not permit null elements |
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* @throws IllegalArgumentException {@inheritDoc} |
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+ |
* @since 1.6 |
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*/ |
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public NavigableSet<E> navigableHeadSet(E toElement) { |
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return new TreeSet<E>(m.navigableHeadMap(toElement)); |
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public NavigableSet<E> headSet(E toElement, boolean inclusive) { |
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return new TreeSet<E>(m.headMap(toElement, inclusive)); |
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} |
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|
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/** |
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* @throws ClassCastException {@inheritDoc} |
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* @throws NullPointerException if <tt>fromElement</tt> is null and |
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* @throws NullPointerException if {@code fromElement} is null and |
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* this set uses natural ordering, or its comparator does |
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* not permit null elements |
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* @throws IllegalArgumentException {@inheritDoc} |
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+ |
* @since 1.6 |
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*/ |
350 |
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public NavigableSet<E> navigableTailSet(E fromElement) { |
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return new TreeSet<E>(m.navigableTailMap(fromElement)); |
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> |
public NavigableSet<E> tailSet(E fromElement, boolean inclusive) { |
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> |
return new TreeSet<E>(m.tailMap(fromElement, inclusive)); |
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} |
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|
354 |
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/** |
308 |
– |
* Equivalent to {@link #navigableSubSet} but with a return type |
309 |
– |
* conforming to the <tt>SortedSet</tt> interface. |
310 |
– |
* |
311 |
– |
* <p>{@inheritDoc} |
312 |
– |
* |
355 |
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* @throws ClassCastException {@inheritDoc} |
356 |
< |
* @throws NullPointerException if <tt>fromElement</tt> or |
357 |
< |
* <tt>toElement</tt> is null and this set uses natural ordering, |
356 |
> |
* @throws NullPointerException if {@code fromElement} or |
357 |
> |
* {@code toElement} is null and this set uses natural ordering, |
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* or its comparator does not permit null elements |
359 |
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* @throws IllegalArgumentException {@inheritDoc} |
360 |
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*/ |
361 |
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public SortedSet<E> subSet(E fromElement, E toElement) { |
362 |
< |
return new TreeSet<E>(m.navigableSubMap(fromElement, toElement)); |
362 |
> |
return subSet(fromElement, true, toElement, false); |
363 |
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} |
364 |
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|
365 |
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/** |
324 |
– |
* Equivalent to {@link #navigableHeadSet} but with a return type |
325 |
– |
* conforming to the <tt>SortedSet</tt> interface. |
326 |
– |
* |
327 |
– |
* <p>{@inheritDoc} |
328 |
– |
* |
366 |
|
* @throws ClassCastException {@inheritDoc} |
367 |
< |
* @throws NullPointerException if <tt>toElement</tt> is null |
367 |
> |
* @throws NullPointerException if {@code toElement} is null |
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* and this set uses natural ordering, or its comparator does |
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* not permit null elements |
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* @throws IllegalArgumentException {@inheritDoc} |
371 |
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*/ |
372 |
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public SortedSet<E> headSet(E toElement) { |
373 |
< |
return new TreeSet<E>(m.navigableHeadMap(toElement)); |
373 |
> |
return headSet(toElement, false); |
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} |
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|
376 |
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/** |
340 |
– |
* Equivalent to {@link #navigableTailSet} but with a return type |
341 |
– |
* conforming to the <tt>SortedSet</tt> interface. |
342 |
– |
* |
343 |
– |
* <p>{@inheritDoc} |
344 |
– |
* |
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|
* @throws ClassCastException {@inheritDoc} |
378 |
< |
* @throws NullPointerException if <tt>fromElement</tt> is null |
378 |
> |
* @throws NullPointerException if {@code fromElement} is null |
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* and this set uses natural ordering, or its comparator does |
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* not permit null elements |
381 |
|
* @throws IllegalArgumentException {@inheritDoc} |
382 |
|
*/ |
383 |
|
public SortedSet<E> tailSet(E fromElement) { |
384 |
< |
return new TreeSet<E>(m.navigableTailMap(fromElement)); |
384 |
> |
return tailSet(fromElement, true); |
385 |
|
} |
386 |
|
|
387 |
|
public Comparator<? super E> comparator() { |
409 |
|
* @throws NullPointerException if the specified element is null |
410 |
|
* and this set uses natural ordering, or its comparator |
411 |
|
* does not permit null elements |
412 |
+ |
* @since 1.6 |
413 |
|
*/ |
414 |
|
public E lower(E e) { |
415 |
|
return m.lowerKey(e); |
420 |
|
* @throws NullPointerException if the specified element is null |
421 |
|
* and this set uses natural ordering, or its comparator |
422 |
|
* does not permit null elements |
423 |
+ |
* @since 1.6 |
424 |
|
*/ |
425 |
|
public E floor(E e) { |
426 |
|
return m.floorKey(e); |
431 |
|
* @throws NullPointerException if the specified element is null |
432 |
|
* and this set uses natural ordering, or its comparator |
433 |
|
* does not permit null elements |
434 |
+ |
* @since 1.6 |
435 |
|
*/ |
436 |
|
public E ceiling(E e) { |
437 |
|
return m.ceilingKey(e); |
442 |
|
* @throws NullPointerException if the specified element is null |
443 |
|
* and this set uses natural ordering, or its comparator |
444 |
|
* does not permit null elements |
445 |
+ |
* @since 1.6 |
446 |
|
*/ |
447 |
|
public E higher(E e) { |
448 |
|
return m.higherKey(e); |
449 |
|
} |
450 |
|
|
451 |
+ |
/** |
452 |
+ |
* @since 1.6 |
453 |
+ |
*/ |
454 |
|
public E pollFirst() { |
455 |
|
Map.Entry<E,?> e = m.pollFirstEntry(); |
456 |
|
return (e == null)? null : e.getKey(); |
457 |
|
} |
458 |
|
|
459 |
+ |
/** |
460 |
+ |
* @since 1.6 |
461 |
+ |
*/ |
462 |
|
public E pollLast() { |
463 |
|
Map.Entry<E,?> e = m.pollLastEntry(); |
464 |
|
return (e == null)? null : e.getKey(); |
465 |
|
} |
466 |
|
|
467 |
|
/** |
468 |
< |
* Returns a shallow copy of this <tt>TreeSet</tt> instance. (The elements |
468 |
> |
* Returns a shallow copy of this {@code TreeSet} instance. (The elements |
469 |
|
* themselves are not cloned.) |
470 |
|
* |
471 |
|
* @return a shallow copy of this set |
479 |
|
} |
480 |
|
|
481 |
|
clone.m = new TreeMap<E,Object>(m); |
440 |
– |
|
482 |
|
return clone; |
483 |
|
} |
484 |
|
|
485 |
|
/** |
486 |
< |
* Save the state of the <tt>TreeSet</tt> instance to a stream (that is, |
486 |
> |
* Save the state of the {@code TreeSet} instance to a stream (that is, |
487 |
|
* serialize it). |
488 |
|
* |
489 |
|
* @serialData Emits the comparator used to order this set, or |
490 |
< |
* <tt>null</tt> if it obeys its elements' natural ordering |
490 |
> |
* {@code null} if it obeys its elements' natural ordering |
491 |
|
* (Object), followed by the size of the set (the number of |
492 |
|
* elements it contains) (int), followed by all of its |
493 |
|
* elements (each an Object) in order (as determined by the |
511 |
|
} |
512 |
|
|
513 |
|
/** |
514 |
< |
* Reconstitute the <tt>TreeSet</tt> instance from a stream (that is, |
514 |
> |
* Reconstitute the {@code TreeSet} instance from a stream (that is, |
515 |
|
* deserialize it). |
516 |
|
*/ |
517 |
|
private void readObject(java.io.ObjectInputStream s) |