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/* |
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* %W% %E% |
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* |
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jsr166 |
1.6 |
* Copyright 2005 Sun Microsystems, Inc. All rights reserved. |
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1.1 |
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. |
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*/ |
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1.8 |
package java.util; |
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/** |
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1.11 |
* A {@link NavigableSet} implementation based on a {@link TreeMap}. |
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* The elements are ordered using their {@linkplain Comparable natural |
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* ordering}, or by a {@link Comparator} provided at set creation |
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* time, depending on which constructor is used. |
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1.1 |
* |
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1.11 |
* <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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* |
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* <p>Note that the ordering maintained by a set (whether or not an explicit |
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1.1 |
* 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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* 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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1.11 |
* just fails to obey the general contract of the <tt>Set</tt> interface. |
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* |
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1.11 |
* <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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1.11 |
* </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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* <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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* 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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* an undetermined time in the future. |
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* |
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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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* 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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1.10 |
* should be used only to detect bugs.</i> |
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1.1 |
* |
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1.10 |
* <p>This class is a member of the |
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* <a href="{@docRoot}/../guide/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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* |
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* @author Josh Bloch |
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* @version %I%, %G% |
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* @see Collection |
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* @see 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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public class TreeSet<E> |
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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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// 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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1.11 |
* 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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this.m = m; |
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} |
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/** |
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1.11 |
* Constructs a new, empty tree set, sorted according to the |
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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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1.11 |
* <tt>e2</tt> 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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*/ |
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public TreeSet() { |
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this(new TreeMap<E,Object>()); |
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} |
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/** |
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1.12 |
* 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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* 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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1.11 |
* |
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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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* 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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this(new TreeMap<E,Object>(comparator)); |
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1.1 |
} |
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/** |
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jsr166 |
1.12 |
* Constructs a new tree set containing the elements in the specified |
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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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jsr166 |
1.11 |
* <tt>ClassCastException</tt> for any elements <tt>e1</tt> and |
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* <tt>e2</tt> 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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* 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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public TreeSet(Collection<? extends E> c) { |
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this(); |
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addAll(c); |
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} |
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/** |
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jsr166 |
1.11 |
* Constructs a new tree set containing the same elements and |
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* using the same ordering as the specified sorted set. |
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1.1 |
* |
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1.11 |
* @param s sorted set whose elements will comprise the new set |
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* @throws NullPointerException if the specified sorted set is null |
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1.1 |
*/ |
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public TreeSet(SortedSet<E> s) { |
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this(s.comparator()); |
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addAll(s); |
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} |
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/** |
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* Returns an iterator over the elements in this set. The elements |
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* are returned in ascending order. |
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* |
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1.11 |
* @return an iterator over the elements in this set |
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1.1 |
*/ |
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public Iterator<E> iterator() { |
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jsr166 |
1.11 |
return m.keySet().iterator(); |
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1.1 |
} |
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/** |
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* Returns an iterator over the elements in this set. The elements |
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* are returned in descending order. |
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* |
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jsr166 |
1.11 |
* @return an iterator over the elements in this set |
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1.1 |
*/ |
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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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* Returns the number of elements in this set (its cardinality). |
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* |
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1.11 |
* @return the number of elements in this set (its cardinality) |
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1.1 |
*/ |
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public int size() { |
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return m.size(); |
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} |
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/** |
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* Returns <tt>true</tt> if this set contains no elements. |
187 |
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* |
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jsr166 |
1.11 |
* @return <tt>true</tt> if this set contains no elements |
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1.1 |
*/ |
190 |
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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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* Returns <tt>true</tt> if this set contains the specified element. |
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* |
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jsr166 |
1.11 |
* @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 |
199 |
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1.1 |
* @throws ClassCastException if the specified object cannot be compared |
200 |
jsr166 |
1.11 |
* with the elements currently in the set |
201 |
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* @throws NullPointerException if the specified element is null and |
202 |
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* this set uses natural ordering and is non-empty, or its |
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* comparator does not permit null elements |
204 |
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1.1 |
*/ |
205 |
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public boolean contains(Object o) { |
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return m.containsKey(o); |
207 |
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} |
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209 |
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/** |
210 |
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* Adds the specified element to this set if it is not already present. |
211 |
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* |
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jsr166 |
1.11 |
* @param e element to be added to this set |
213 |
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1.1 |
* @return <tt>true</tt> if the set did not already contain the specified |
214 |
jsr166 |
1.11 |
* element |
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1.1 |
* @throws ClassCastException if the specified object cannot be compared |
216 |
jsr166 |
1.11 |
* with the elements currently in the set |
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* @throws NullPointerException if the specified element is null and |
218 |
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* this set uses natural ordering and is non-empty, or its |
219 |
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* comparator does not permit null elements |
220 |
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1.1 |
*/ |
221 |
jsr166 |
1.7 |
public boolean add(E e) { |
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return m.put(e, PRESENT)==null; |
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1.1 |
} |
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/** |
226 |
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* Removes the specified element from this set if it is present. |
227 |
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* |
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jsr166 |
1.11 |
* @param o object to be removed from this set, if present |
229 |
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* @return <tt>true</tt> if the set contained the specified element |
230 |
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1.1 |
* @throws ClassCastException if the specified object cannot be compared |
231 |
jsr166 |
1.11 |
* with the elements currently in the set |
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* @throws NullPointerException if the specified element is null and |
233 |
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* this set uses natural ordering and is non-empty, or its |
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* comparator does not permit null elements |
235 |
dl |
1.1 |
*/ |
236 |
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public boolean remove(Object o) { |
237 |
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return m.remove(o)==PRESENT; |
238 |
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} |
239 |
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240 |
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/** |
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* Removes all of the elements from this set. |
242 |
jsr166 |
1.11 |
* The set will be empty after this call returns. |
243 |
dl |
1.1 |
*/ |
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public void clear() { |
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m.clear(); |
246 |
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} |
247 |
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248 |
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/** |
249 |
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* Adds all of the elements in the specified collection to this set. |
250 |
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* |
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* @param c elements to be added |
252 |
jsr166 |
1.11 |
* @return <tt>true</tt> if this set changed as a result of the call |
253 |
dl |
1.1 |
* @throws ClassCastException if the elements provided cannot be compared |
254 |
jsr166 |
1.11 |
* with the elements currently in the set |
255 |
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* @throws NullPointerException if the specified collection is null or |
256 |
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* if any element is null and this set uses natural ordering, or |
257 |
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* its comparator does not permit null elements |
258 |
dl |
1.1 |
*/ |
259 |
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public boolean addAll(Collection<? extends E> c) { |
260 |
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// Use linear-time version if applicable |
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if (m.size()==0 && c.size() > 0 && |
262 |
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c instanceof SortedSet && |
263 |
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m instanceof TreeMap) { |
264 |
jsr166 |
1.9 |
SortedSet<? extends E> set = (SortedSet<? extends E>) c; |
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1.1 |
TreeMap<E,Object> map = (TreeMap<E, Object>) m; |
266 |
jsr166 |
1.9 |
Comparator<? super E> cc = (Comparator<? super E>) set.comparator(); |
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1.1 |
Comparator<? super E> mc = map.comparator(); |
268 |
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if (cc==mc || (cc != null && cc.equals(mc))) { |
269 |
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map.addAllForTreeSet(set, PRESENT); |
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return true; |
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} |
272 |
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} |
273 |
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return super.addAll(c); |
274 |
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} |
275 |
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276 |
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/** |
277 |
jsr166 |
1.11 |
* @throws ClassCastException {@inheritDoc} |
278 |
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1.1 |
* @throws NullPointerException if <tt>fromElement</tt> or |
279 |
jsr166 |
1.11 |
* <tt>toElement</tt> is null and this set uses natural ordering, |
280 |
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* or its comparator does not permit null elements |
281 |
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* @throws IllegalArgumentException {@inheritDoc} |
282 |
dl |
1.1 |
*/ |
283 |
dl |
1.3 |
public NavigableSet<E> navigableSubSet(E fromElement, E toElement) { |
284 |
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return new TreeSet<E>(m.navigableSubMap(fromElement, toElement)); |
285 |
dl |
1.1 |
} |
286 |
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287 |
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/** |
288 |
jsr166 |
1.11 |
* @throws ClassCastException {@inheritDoc} |
289 |
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* @throws NullPointerException if <tt>toElement</tt> is null and |
290 |
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* this set uses natural ordering, or its comparator does |
291 |
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* not permit null elements |
292 |
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* @throws IllegalArgumentException {@inheritDoc} |
293 |
dl |
1.1 |
*/ |
294 |
dl |
1.3 |
public NavigableSet<E> navigableHeadSet(E toElement) { |
295 |
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return new TreeSet<E>(m.navigableHeadMap(toElement)); |
296 |
dl |
1.1 |
} |
297 |
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298 |
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/** |
299 |
jsr166 |
1.11 |
* @throws ClassCastException {@inheritDoc} |
300 |
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* @throws NullPointerException if <tt>fromElement</tt> is null and |
301 |
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* this set uses natural ordering, or its comparator does |
302 |
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* not permit null elements |
303 |
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* @throws IllegalArgumentException {@inheritDoc} |
304 |
dl |
1.1 |
*/ |
305 |
dl |
1.3 |
public NavigableSet<E> navigableTailSet(E fromElement) { |
306 |
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return new TreeSet<E>(m.navigableTailMap(fromElement)); |
307 |
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} |
308 |
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309 |
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/** |
310 |
jsr166 |
1.11 |
* Equivalent to {@link #navigableSubSet} but with a return type |
311 |
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* conforming to the <tt>SortedSet</tt> interface. |
312 |
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* |
313 |
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* <p>{@inheritDoc} |
314 |
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* |
315 |
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* @throws ClassCastException {@inheritDoc} |
316 |
dl |
1.3 |
* @throws NullPointerException if <tt>fromElement</tt> or |
317 |
jsr166 |
1.11 |
* <tt>toElement</tt> is null and this set uses natural ordering, |
318 |
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* or its comparator does not permit null elements |
319 |
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* @throws IllegalArgumentException {@inheritDoc} |
320 |
dl |
1.3 |
*/ |
321 |
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public SortedSet<E> subSet(E fromElement, E toElement) { |
322 |
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return new TreeSet<E>(m.navigableSubMap(fromElement, toElement)); |
323 |
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} |
324 |
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325 |
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/** |
326 |
jsr166 |
1.11 |
* Equivalent to {@link #navigableHeadSet} but with a return type |
327 |
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* conforming to the <tt>SortedSet</tt> interface. |
328 |
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* |
329 |
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* <p>{@inheritDoc} |
330 |
dl |
1.3 |
* |
331 |
jsr166 |
1.11 |
* @throws ClassCastException {@inheritDoc} |
332 |
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* @throws NullPointerException if <tt>toElement</tt> is null |
333 |
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* and this set uses natural ordering, or its comparator does |
334 |
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* not permit null elements |
335 |
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* @throws IllegalArgumentException {@inheritDoc} |
336 |
dl |
1.3 |
*/ |
337 |
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public SortedSet<E> headSet(E toElement) { |
338 |
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return new TreeSet<E>(m.navigableHeadMap(toElement)); |
339 |
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} |
340 |
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341 |
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/** |
342 |
jsr166 |
1.11 |
* Equivalent to {@link #navigableTailSet} but with a return type |
343 |
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* conforming to the <tt>SortedSet</tt> interface. |
344 |
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* |
345 |
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* <p>{@inheritDoc} |
346 |
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* |
347 |
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* @throws ClassCastException {@inheritDoc} |
348 |
|
|
* @throws NullPointerException if <tt>fromElement</tt> is null |
349 |
|
|
* and this set uses natural ordering, or its comparator does |
350 |
|
|
* not permit null elements |
351 |
|
|
* @throws IllegalArgumentException {@inheritDoc} |
352 |
dl |
1.3 |
*/ |
353 |
|
|
public SortedSet<E> tailSet(E fromElement) { |
354 |
|
|
return new TreeSet<E>(m.navigableTailMap(fromElement)); |
355 |
dl |
1.1 |
} |
356 |
|
|
|
357 |
|
|
public Comparator<? super E> comparator() { |
358 |
|
|
return m.comparator(); |
359 |
|
|
} |
360 |
|
|
|
361 |
|
|
/** |
362 |
jsr166 |
1.11 |
* @throws NoSuchElementException {@inheritDoc} |
363 |
dl |
1.1 |
*/ |
364 |
|
|
public E first() { |
365 |
|
|
return m.firstKey(); |
366 |
|
|
} |
367 |
|
|
|
368 |
|
|
/** |
369 |
jsr166 |
1.11 |
* @throws NoSuchElementException {@inheritDoc} |
370 |
dl |
1.1 |
*/ |
371 |
|
|
public E last() { |
372 |
|
|
return m.lastKey(); |
373 |
|
|
} |
374 |
|
|
|
375 |
|
|
// NavigableSet API methods |
376 |
|
|
|
377 |
|
|
/** |
378 |
jsr166 |
1.11 |
* @throws ClassCastException {@inheritDoc} |
379 |
|
|
* @throws NullPointerException if the specified element is null and |
380 |
|
|
* this set uses natural ordering and is non-empty, |
381 |
|
|
* or its comparator does not permit null elements |
382 |
dl |
1.1 |
*/ |
383 |
jsr166 |
1.11 |
public E lower(E e) { |
384 |
|
|
return m.lowerKey(e); |
385 |
dl |
1.1 |
} |
386 |
|
|
|
387 |
|
|
/** |
388 |
jsr166 |
1.11 |
* @throws ClassCastException {@inheritDoc} |
389 |
|
|
* @throws NullPointerException if the specified element is null and |
390 |
|
|
* this set uses natural ordering and is non-empty, |
391 |
|
|
* or its comparator does not permit null elements |
392 |
dl |
1.1 |
*/ |
393 |
jsr166 |
1.11 |
public E floor(E e) { |
394 |
|
|
return m.floorKey(e); |
395 |
dl |
1.1 |
} |
396 |
|
|
|
397 |
|
|
/** |
398 |
jsr166 |
1.11 |
* @throws ClassCastException {@inheritDoc} |
399 |
|
|
* @throws NullPointerException if the specified element is null and |
400 |
|
|
* this set uses natural ordering and is non-empty, |
401 |
|
|
* or its comparator does not permit null elements |
402 |
dl |
1.1 |
*/ |
403 |
jsr166 |
1.11 |
public E ceiling(E e) { |
404 |
|
|
return m.ceilingKey(e); |
405 |
dl |
1.1 |
} |
406 |
|
|
|
407 |
|
|
/** |
408 |
jsr166 |
1.11 |
* @throws ClassCastException {@inheritDoc} |
409 |
|
|
* @throws NullPointerException if the specified element is null and |
410 |
|
|
* this set uses natural ordering and is non-empty, |
411 |
|
|
* or its comparator does not permit null elements |
412 |
dl |
1.1 |
*/ |
413 |
jsr166 |
1.7 |
public E higher(E e) { |
414 |
|
|
return m.higherKey(e); |
415 |
dl |
1.1 |
} |
416 |
|
|
|
417 |
|
|
public E pollFirst() { |
418 |
|
|
Map.Entry<E,?> e = m.pollFirstEntry(); |
419 |
|
|
return (e == null)? null : e.getKey(); |
420 |
|
|
} |
421 |
|
|
|
422 |
|
|
public E pollLast() { |
423 |
|
|
Map.Entry<E,?> e = m.pollLastEntry(); |
424 |
|
|
return (e == null)? null : e.getKey(); |
425 |
|
|
} |
426 |
|
|
|
427 |
|
|
/** |
428 |
|
|
* Returns a shallow copy of this <tt>TreeSet</tt> instance. (The elements |
429 |
|
|
* themselves are not cloned.) |
430 |
|
|
* |
431 |
jsr166 |
1.11 |
* @return a shallow copy of this set |
432 |
dl |
1.1 |
*/ |
433 |
|
|
public Object clone() { |
434 |
|
|
TreeSet<E> clone = null; |
435 |
|
|
try { |
436 |
|
|
clone = (TreeSet<E>) super.clone(); |
437 |
|
|
} catch (CloneNotSupportedException e) { |
438 |
|
|
throw new InternalError(); |
439 |
|
|
} |
440 |
|
|
|
441 |
|
|
clone.m = new TreeMap<E,Object>(m); |
442 |
|
|
|
443 |
|
|
return clone; |
444 |
|
|
} |
445 |
|
|
|
446 |
|
|
/** |
447 |
|
|
* Save the state of the <tt>TreeSet</tt> instance to a stream (that is, |
448 |
|
|
* serialize it). |
449 |
|
|
* |
450 |
|
|
* @serialData Emits the comparator used to order this set, or |
451 |
jsr166 |
1.11 |
* <tt>null</tt> if it obeys its elements' natural ordering |
452 |
|
|
* (Object), followed by the size of the set (the number of |
453 |
|
|
* elements it contains) (int), followed by all of its |
454 |
|
|
* elements (each an Object) in order (as determined by the |
455 |
|
|
* set's Comparator, or by the elements' natural ordering if |
456 |
dl |
1.1 |
* the set has no Comparator). |
457 |
|
|
*/ |
458 |
|
|
private void writeObject(java.io.ObjectOutputStream s) |
459 |
|
|
throws java.io.IOException { |
460 |
|
|
// Write out any hidden stuff |
461 |
|
|
s.defaultWriteObject(); |
462 |
|
|
|
463 |
|
|
// Write out Comparator |
464 |
|
|
s.writeObject(m.comparator()); |
465 |
|
|
|
466 |
|
|
// Write out size |
467 |
|
|
s.writeInt(m.size()); |
468 |
|
|
|
469 |
|
|
// Write out all elements in the proper order. |
470 |
|
|
for (Iterator i=m.keySet().iterator(); i.hasNext(); ) |
471 |
|
|
s.writeObject(i.next()); |
472 |
|
|
} |
473 |
|
|
|
474 |
|
|
/** |
475 |
|
|
* Reconstitute the <tt>TreeSet</tt> instance from a stream (that is, |
476 |
|
|
* deserialize it). |
477 |
|
|
*/ |
478 |
|
|
private void readObject(java.io.ObjectInputStream s) |
479 |
|
|
throws java.io.IOException, ClassNotFoundException { |
480 |
|
|
// Read in any hidden stuff |
481 |
|
|
s.defaultReadObject(); |
482 |
|
|
|
483 |
|
|
// Read in Comparator |
484 |
jsr166 |
1.9 |
Comparator<? super E> c = (Comparator<? super E>) s.readObject(); |
485 |
dl |
1.1 |
|
486 |
|
|
// Create backing TreeMap |
487 |
|
|
TreeMap<E,Object> tm; |
488 |
|
|
if (c==null) |
489 |
|
|
tm = new TreeMap<E,Object>(); |
490 |
|
|
else |
491 |
|
|
tm = new TreeMap<E,Object>(c); |
492 |
|
|
m = tm; |
493 |
|
|
|
494 |
|
|
// Read in size |
495 |
|
|
int size = s.readInt(); |
496 |
|
|
|
497 |
|
|
tm.readTreeSet(size, s, PRESENT); |
498 |
|
|
} |
499 |
|
|
|
500 |
|
|
private static final long serialVersionUID = -2479143000061671589L; |
501 |
|
|
} |