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/* |
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* %W% %E% |
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* |
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* Copyright 2005 Sun Microsystems, Inc. All rights reserved. |
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* Copyright 2006 Sun Microsystems, Inc. All rights reserved. |
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* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. |
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*/ |
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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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* @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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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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* 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(Object)} 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(Object)} 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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/** |
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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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/** |
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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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/** |
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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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* {@code (o==null ? e==null : o.equals(e))}. |
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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 and |
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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 |
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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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public boolean contains(Object o) { |
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return m.containsKey(o); |
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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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* {@code (e==null ? e2==null : e.equals(e2))}. |
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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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< |
* @throws NullPointerException if the specified element is null and |
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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 |
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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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public boolean add(E e) { |
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return m.put(e, PRESENT)==null; |
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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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* {@code (o==null ? e==null : o.equals(e))}, |
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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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< |
* @throws NullPointerException if the specified element is null and |
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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 |
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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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public boolean remove(Object o) { |
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return m.remove(o)==PRESENT; |
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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 |
| 302 |
> |
* does not permit null elements |
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|
* @throws IllegalArgumentException {@inheritDoc} |
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+ |
* @since 1.6 |
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*/ |
| 306 |
< |
public NavigableSet<E> navigableSubSet(E fromElement, E toElement) { |
| 307 |
< |
return new TreeSet<E>(m.navigableSubMap(fromElement, toElement)); |
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> |
public NavigableSet<E> subSet(E fromElement, boolean fromInclusive, |
| 307 |
> |
E toElement, boolean toInclusive) { |
| 308 |
> |
return new TreeSet<E>(m.subMap(fromElement, fromInclusive, |
| 309 |
> |
toElement, toInclusive)); |
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} |
| 311 |
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|
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/** |
| 313 |
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* @throws ClassCastException {@inheritDoc} |
| 314 |
< |
* @throws NullPointerException if <tt>toElement</tt> is null and |
| 314 |
> |
* @throws NullPointerException if {@code toElement} is null and |
| 315 |
|
* this set uses natural ordering, or its comparator does |
| 316 |
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* not permit null elements |
| 317 |
|
* @throws IllegalArgumentException {@inheritDoc} |
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+ |
* @since 1.6 |
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*/ |
| 320 |
< |
public NavigableSet<E> navigableHeadSet(E toElement) { |
| 321 |
< |
return new TreeSet<E>(m.navigableHeadMap(toElement)); |
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> |
public NavigableSet<E> headSet(E toElement, boolean inclusive) { |
| 321 |
> |
return new TreeSet<E>(m.headMap(toElement, inclusive)); |
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} |
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|
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/** |
| 325 |
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* @throws ClassCastException {@inheritDoc} |
| 326 |
< |
* @throws NullPointerException if <tt>fromElement</tt> is null and |
| 326 |
> |
* @throws NullPointerException if {@code fromElement} is null and |
| 327 |
|
* this set uses natural ordering, or its comparator does |
| 328 |
|
* not permit null elements |
| 329 |
|
* @throws IllegalArgumentException {@inheritDoc} |
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+ |
* @since 1.6 |
| 331 |
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*/ |
| 332 |
< |
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) { |
| 333 |
> |
return new TreeSet<E>(m.tailMap(fromElement, inclusive)); |
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|
} |
| 335 |
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|
| 336 |
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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 |
– |
* |
| 337 |
|
* @throws ClassCastException {@inheritDoc} |
| 338 |
< |
* @throws NullPointerException if <tt>fromElement</tt> or |
| 339 |
< |
* <tt>toElement</tt> is null and this set uses natural ordering, |
| 338 |
> |
* @throws NullPointerException if {@code fromElement} or |
| 339 |
> |
* {@code toElement} is null and this set uses natural ordering, |
| 340 |
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* or its comparator does not permit null elements |
| 341 |
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* @throws IllegalArgumentException {@inheritDoc} |
| 342 |
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*/ |
| 343 |
|
public SortedSet<E> subSet(E fromElement, E toElement) { |
| 344 |
< |
return new TreeSet<E>(m.navigableSubMap(fromElement, toElement)); |
| 344 |
> |
return subSet(fromElement, true, toElement, false); |
| 345 |
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} |
| 346 |
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|
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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 |
– |
* |
| 348 |
|
* @throws ClassCastException {@inheritDoc} |
| 349 |
< |
* @throws NullPointerException if <tt>toElement</tt> is null |
| 349 |
> |
* @throws NullPointerException if {@code toElement} is null |
| 350 |
|
* and this set uses natural ordering, or its comparator does |
| 351 |
|
* not permit null elements |
| 352 |
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* @throws IllegalArgumentException {@inheritDoc} |
| 353 |
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*/ |
| 354 |
|
public SortedSet<E> headSet(E toElement) { |
| 355 |
< |
return new TreeSet<E>(m.navigableHeadMap(toElement)); |
| 355 |
> |
return headSet(toElement, false); |
| 356 |
|
} |
| 357 |
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|
| 358 |
|
/** |
| 340 |
– |
* Equivalent to {@link #navigableTailSet} but with a return type |
| 341 |
– |
* conforming to the <tt>SortedSet</tt> interface. |
| 342 |
– |
* |
| 343 |
– |
* <p>{@inheritDoc} |
| 344 |
– |
* |
| 359 |
|
* @throws ClassCastException {@inheritDoc} |
| 360 |
< |
* @throws NullPointerException if <tt>fromElement</tt> is null |
| 360 |
> |
* @throws NullPointerException if {@code fromElement} is null |
| 361 |
|
* and this set uses natural ordering, or its comparator does |
| 362 |
|
* not permit null elements |
| 363 |
|
* @throws IllegalArgumentException {@inheritDoc} |
| 364 |
|
*/ |
| 365 |
|
public SortedSet<E> tailSet(E fromElement) { |
| 366 |
< |
return new TreeSet<E>(m.navigableTailMap(fromElement)); |
| 366 |
> |
return tailSet(fromElement, true); |
| 367 |
|
} |
| 368 |
|
|
| 369 |
|
public Comparator<? super E> comparator() { |
| 388 |
|
|
| 389 |
|
/** |
| 390 |
|
* @throws ClassCastException {@inheritDoc} |
| 391 |
< |
* @throws NullPointerException if the specified element is null and |
| 392 |
< |
* this set uses natural ordering and is non-empty, |
| 393 |
< |
* or its comparator does not permit null elements |
| 391 |
> |
* @throws NullPointerException if the specified element is null |
| 392 |
> |
* and this set uses natural ordering, or its comparator |
| 393 |
> |
* does not permit null elements |
| 394 |
> |
* @since 1.6 |
| 395 |
|
*/ |
| 396 |
|
public E lower(E e) { |
| 397 |
|
return m.lowerKey(e); |
| 399 |
|
|
| 400 |
|
/** |
| 401 |
|
* @throws ClassCastException {@inheritDoc} |
| 402 |
< |
* @throws NullPointerException if the specified element is null and |
| 403 |
< |
* this set uses natural ordering and is non-empty, |
| 404 |
< |
* or its comparator does not permit null elements |
| 402 |
> |
* @throws NullPointerException if the specified element is null |
| 403 |
> |
* and this set uses natural ordering, or its comparator |
| 404 |
> |
* does not permit null elements |
| 405 |
> |
* @since 1.6 |
| 406 |
|
*/ |
| 407 |
|
public E floor(E e) { |
| 408 |
|
return m.floorKey(e); |
| 410 |
|
|
| 411 |
|
/** |
| 412 |
|
* @throws ClassCastException {@inheritDoc} |
| 413 |
< |
* @throws NullPointerException if the specified element is null and |
| 414 |
< |
* this set uses natural ordering and is non-empty, |
| 415 |
< |
* or its comparator does not permit null elements |
| 413 |
> |
* @throws NullPointerException if the specified element is null |
| 414 |
> |
* and this set uses natural ordering, or its comparator |
| 415 |
> |
* does not permit null elements |
| 416 |
> |
* @since 1.6 |
| 417 |
|
*/ |
| 418 |
|
public E ceiling(E e) { |
| 419 |
|
return m.ceilingKey(e); |
| 421 |
|
|
| 422 |
|
/** |
| 423 |
|
* @throws ClassCastException {@inheritDoc} |
| 424 |
< |
* @throws NullPointerException if the specified element is null and |
| 425 |
< |
* this set uses natural ordering and is non-empty, |
| 426 |
< |
* or its comparator does not permit null elements |
| 424 |
> |
* @throws NullPointerException if the specified element is null |
| 425 |
> |
* and this set uses natural ordering, or its comparator |
| 426 |
> |
* does not permit null elements |
| 427 |
> |
* @since 1.6 |
| 428 |
|
*/ |
| 429 |
|
public E higher(E e) { |
| 430 |
|
return m.higherKey(e); |
| 431 |
|
} |
| 432 |
|
|
| 433 |
+ |
/** |
| 434 |
+ |
* @since 1.6 |
| 435 |
+ |
*/ |
| 436 |
|
public E pollFirst() { |
| 437 |
|
Map.Entry<E,?> e = m.pollFirstEntry(); |
| 438 |
|
return (e == null)? null : e.getKey(); |
| 439 |
|
} |
| 440 |
|
|
| 441 |
+ |
/** |
| 442 |
+ |
* @since 1.6 |
| 443 |
+ |
*/ |
| 444 |
|
public E pollLast() { |
| 445 |
|
Map.Entry<E,?> e = m.pollLastEntry(); |
| 446 |
|
return (e == null)? null : e.getKey(); |
| 447 |
|
} |
| 448 |
|
|
| 449 |
|
/** |
| 450 |
< |
* Returns a shallow copy of this <tt>TreeSet</tt> instance. (The elements |
| 450 |
> |
* Returns a shallow copy of this {@code TreeSet} instance. (The elements |
| 451 |
|
* themselves are not cloned.) |
| 452 |
|
* |
| 453 |
|
* @return a shallow copy of this set |
| 461 |
|
} |
| 462 |
|
|
| 463 |
|
clone.m = new TreeMap<E,Object>(m); |
| 440 |
– |
|
| 464 |
|
return clone; |
| 465 |
|
} |
| 466 |
|
|
| 467 |
|
/** |
| 468 |
< |
* Save the state of the <tt>TreeSet</tt> instance to a stream (that is, |
| 468 |
> |
* Save the state of the {@code TreeSet} instance to a stream (that is, |
| 469 |
|
* serialize it). |
| 470 |
|
* |
| 471 |
|
* @serialData Emits the comparator used to order this set, or |
| 472 |
< |
* <tt>null</tt> if it obeys its elements' natural ordering |
| 472 |
> |
* {@code null} if it obeys its elements' natural ordering |
| 473 |
|
* (Object), followed by the size of the set (the number of |
| 474 |
|
* elements it contains) (int), followed by all of its |
| 475 |
|
* elements (each an Object) in order (as determined by the |
| 493 |
|
} |
| 494 |
|
|
| 495 |
|
/** |
| 496 |
< |
* Reconstitute the <tt>TreeSet</tt> instance from a stream (that is, |
| 496 |
> |
* Reconstitute the {@code TreeSet} instance from a stream (that is, |
| 497 |
|
* deserialize it). |
| 498 |
|
*/ |
| 499 |
|
private void readObject(java.io.ObjectInputStream s) |
