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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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package jsr166x; |
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* ascending order, sorted according to the <i>natural order</i> for |
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* the element's class (see {@link Comparable}), or by the comparator |
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* provided at creation time, depending on which constructor is |
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* used.<p> |
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* used. |
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* |
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* This implementation provides expected average <i>log(n)</i> time |
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* cost for the <tt>contains</tt>, <tt>add</tt>, and <tt>remove</tt> |
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* <p>This implementation provides expected average <i>log(n)</i> time |
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* cost for the {@code contains}, {@code add}, and {@code remove} |
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* operations and their variants. Insertion, removal, and access |
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* operations safely execute concurrently by multiple |
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* threads. Iterators are <i>weakly consistent</i>, returning elements |
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* ConcurrentModificationException}, and may proceed concurrently with |
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* other operations. |
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* |
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* <p>Beware that, unlike in most collections, the <tt>size</tt> |
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* <p>Beware that, unlike in most collections, the {@code size} |
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* method is <em>not</em> a constant-time operation. Because of the |
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* asynchronous nature of these sets, determining the current number |
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* of elements requires a traversal of the elements. Additionally, the |
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* bulk operations <tt>addAll</tt>, <tt>removeAll</tt>, |
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* <<tt>retainAll</tt>, and tt>containsAll</tt> are <em>not</em> |
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* bulk operations {@code addAll}, {@code removeAll}, |
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* {@code retainAll}, and {@code containsAll} are <em>not</em> |
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* guaranteed to be performed atomically. For example, an iterator |
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* operating concurrently with an <tt>addAll</tt> operation might view |
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* operating concurrently with an {@code addAll} operation might view |
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* only some of the added elements. |
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* |
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* <p>This class and its iterators implement all of the |
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* <em>optional</em> methods of the {@link Set} and {@link Iterator} |
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* interfaces. Like most other concurrent collection implementations, |
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* this class does not permit the use of <tt>null</tt> elements. |
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* because <tt>null</tt> arguments and return values cannot be reliably |
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* this class does not permit the use of {@code null} elements. |
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* because {@code null} arguments and return values cannot be reliably |
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* distinguished from the absence of elements. |
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* |
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* @author Doug Lea |
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* comparator. |
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* |
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* @param c the comparator that will be used to sort this set. A |
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* <tt>null</tt> value indicates that the elements' <i>natural |
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* {@code null} value indicates that the elements' <i>natural |
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* ordering</i> should be used. |
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*/ |
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public ConcurrentSkipListSet(Comparator<? super E> c) { |
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* Constructs a new set containing the elements in the specified |
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* collection, sorted according to the elements' <i>natural order</i>. |
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* |
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* @param c The elements that will comprise the new set. |
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* @param c The elements that will comprise the new set |
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* |
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* @throws ClassCastException if the elements in the specified |
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* collection are not comparable, or are not mutually comparable. |
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* collection are not comparable, or are not mutually comparable |
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* @throws NullPointerException if the specified collection is |
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* <tt>null</tt>. |
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* {@code null} |
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*/ |
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public ConcurrentSkipListSet(Collection<? extends E> c) { |
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m = new ConcurrentSkipListMap<E,Object>(); |
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* Constructs a new set containing the same elements as the specified |
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* sorted set, sorted according to the same ordering. |
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* |
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* @param s sorted set whose elements will comprise the new set. |
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* @param s sorted set whose elements will comprise the new set |
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* @throws NullPointerException if the specified sorted set is |
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* <tt>null</tt>. |
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* {@code null} |
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*/ |
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public ConcurrentSkipListSet(SortedSet<E> s) { |
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m = new ConcurrentSkipListMap<E,Object>(s.comparator()); |
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* Returns a shallow copy of this set. (The elements themselves |
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* are not cloned.) |
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* |
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* @return a shallow copy of this set. |
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* @return a shallow copy of this set |
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*/ |
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public Object clone() { |
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ConcurrentSkipListSet<E> clone = null; |
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/** |
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* Returns the number of elements in this set. If this set |
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* contains more than <tt>Integer.MAX_VALUE</tt> elements, it |
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* returns <tt>Integer.MAX_VALUE</tt>. |
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* contains more than {@code Integer.MAX_VALUE} elements, it |
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* returns {@code Integer.MAX_VALUE}. |
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* |
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* <p>Beware that, unlike in most collections, this method is |
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* <em>NOT</em> a constant-time operation. Because of the |
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* will be inaccurate. Thus, this method is typically not very |
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* useful in concurrent applications. |
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* |
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* @return the number of elements in this set. |
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* @return the number of elements in this set |
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*/ |
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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. |
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* @return <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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* @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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* 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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* |
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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 the 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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* |
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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 o is <tt>null</tt>. |
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* with the elements currently in the set |
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* @throws NullPointerException if o is {@code null} |
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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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* Adds the specified element to this set if it is not already present. |
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* |
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* @param o 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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* element. |
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* @param o element to be added to this set |
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* @return {@code true} if the set did not already contain the specified |
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* element |
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* |
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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 o is <tt>null</tt>. |
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* with the elements currently in the set |
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* @throws NullPointerException if o is {@code null} |
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*/ |
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public boolean add(E o) { |
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return m.putIfAbsent(o, Boolean.TRUE) == null; |
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/** |
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* Removes the specified element from this set if it is present. |
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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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* @param o object to be removed from this set, if present |
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* @return {@code true} if the set contained the specified element |
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* |
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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 o is <tt>null</tt>. |
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* with the elements currently in the set |
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* @throws NullPointerException if o is {@code null} |
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*/ |
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public boolean remove(Object o) { |
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return m.removep(o); |
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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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* @return an iterator over the elements in this set. |
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* @return an iterator over the elements in this set |
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*/ |
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public Iterator<E> iterator() { |
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return m.keyIterator(); |
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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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* @return an iterator over the elements in this set. |
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* @return an iterator over the elements in this set |
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*/ |
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public Iterator<E> descendingIterator() { |
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return m.descendingKeyIterator(); |
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/** |
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* Compares the specified object with this set for equality. Returns |
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* <tt>true</tt> if the specified object is also a set, the two sets |
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* {@code true} if the specified object is also a set, the two sets |
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* have the same size, and every member of the specified set is |
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* contained in this set (or equivalently, every member of this set is |
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* contained in the specified set). This definition ensures that the |
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* equals method works properly across different implementations of the |
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* set interface. |
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* |
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* @param o Object to be compared for equality with this set. |
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* @return <tt>true</tt> if the specified Object is equal to this set. |
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* @param o Object to be compared for equality with this set |
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* @return {@code true} if the specified Object is equal to this set |
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*/ |
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public boolean equals(Object o) { |
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// Override AbstractSet version to avoid calling size() |
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Collection c = (Collection) o; |
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try { |
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return containsAll(c) && c.containsAll(this); |
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} catch (ClassCastException unused) { |
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} catch (ClassCastException unused) { |
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return false; |
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} catch (NullPointerException unused) { |
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return false; |
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* value is the <i>asymmetric set difference</i> of the two sets. |
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* |
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* @param c collection that defines which elements will be removed from |
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* this set. |
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* @return <tt>true</tt> if this set changed as a result of the call. |
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* this set |
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* @return {@code true} if this set changed as a result of the call |
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* |
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* @throws ClassCastException if the types of one or more elements in this |
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* set are incompatible with the specified collection |
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* @throws NullPointerException if the specified collection, or any |
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* of its elements are <tt>null</tt>. |
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* of its elements are {@code null} |
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*/ |
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public boolean removeAll(Collection<?> c) { |
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// Override AbstractSet version to avoid unnecessary call to size() |
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|
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/** |
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* Returns an element greater than or equal to the given element, or |
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* <tt>null</tt> if there is no such element. |
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* {@code null} if there is no such element. |
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* |
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* @param o the value to match |
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* @return an element greater than or equal to given element, or |
295 |
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* <tt>null</tt> if there is no such element. |
295 |
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* {@code null} if there is no such element |
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* @throws ClassCastException if o cannot be compared with the elements |
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* currently in the set. |
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* @throws NullPointerException if o is <tt>null</tt> |
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* currently in the set |
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* @throws NullPointerException if o is {@code null} |
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*/ |
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public E ceiling(E o) { |
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return m.ceilingKey(o); |
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|
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/** |
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* Returns an element strictly less than the given element, or |
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* <tt>null</tt> if there is no such element. |
306 |
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* {@code null} if there is no such element. |
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* |
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* @param o the value to match |
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* @return the greatest element less than the given element, or |
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* <tt>null</tt> if there is no such element. |
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* {@code null} if there is no such element |
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* @throws ClassCastException if o cannot be compared with the elements |
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* currently in the set. |
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* @throws NullPointerException if o is <tt>null</tt>. |
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* currently in the set |
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* @throws NullPointerException if o is {@code null} |
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*/ |
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public E lower(E o) { |
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return m.lowerKey(o); |
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|
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/** |
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* Returns an element less than or equal to the given element, or |
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* <tt>null</tt> if there is no such element. |
321 |
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* {@code null} if there is no such element. |
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* |
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* @param o the value to match |
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* @return the greatest element less than or equal to given |
325 |
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* element, or <tt>null</tt> if there is no such element. |
325 |
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* element, or {@code null} if there is no such element |
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* @throws ClassCastException if o cannot be compared with the elements |
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* currently in the set. |
328 |
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* @throws NullPointerException if o is <tt>null</tt>. |
327 |
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* currently in the set |
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* @throws NullPointerException if o is {@code null} |
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*/ |
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public E floor(E o) { |
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return m.floorKey(o); |
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|
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/** |
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* Returns an element strictly greater than the given element, or |
336 |
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* <tt>null</tt> if there is no such element. |
336 |
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* {@code null} if there is no such element. |
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* |
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* @param o the value to match |
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* @return the least element greater than the given element, or |
340 |
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* <tt>null</tt> if there is no such element. |
340 |
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* {@code null} if there is no such element |
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* @throws ClassCastException if o cannot be compared with the elements |
342 |
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* currently in the set. |
343 |
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* @throws NullPointerException if o is <tt>null</tt>. |
342 |
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* currently in the set |
343 |
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* @throws NullPointerException if o is {@code null} |
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*/ |
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public E higher(E o) { |
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return m.higherKey(o); |
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/** |
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* Retrieves and removes the first (lowest) element. |
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* |
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* @return the least element, or <tt>null</tt> if empty. |
352 |
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* @return the least element, or {@code null} if empty |
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*/ |
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public E pollFirst() { |
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return m.pollFirstKey(); |
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/** |
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* Retrieves and removes the last (highest) element. |
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* |
361 |
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* @return the last element, or <tt>null</tt> if empty. |
361 |
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* @return the last element, or {@code null} if empty |
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*/ |
363 |
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public E pollLast() { |
364 |
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return m.pollLastKey(); |
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|
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|
371 |
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/** |
372 |
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* Returns the comparator used to order this set, or <tt>null</tt> |
372 |
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* Returns the comparator used to order this set, or {@code null} |
373 |
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* if this set uses its elements natural ordering. |
374 |
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* |
375 |
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* @return the comparator used to order this set, or <tt>null</tt> |
376 |
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* if this set uses its elements natural ordering. |
375 |
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* @return the comparator used to order this set, or {@code null} |
376 |
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* if this set uses its elements natural ordering |
377 |
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*/ |
378 |
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public Comparator<? super E> comparator() { |
379 |
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return m.comparator(); |
382 |
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/** |
383 |
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* Returns the first (lowest) element currently in this set. |
384 |
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* |
385 |
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* @return the first (lowest) element currently in this set. |
386 |
< |
* @throws NoSuchElementException sorted set is empty. |
385 |
> |
* @return the first (lowest) element currently in this set |
386 |
> |
* @throws NoSuchElementException sorted set is empty |
387 |
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*/ |
388 |
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public E first() { |
389 |
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return m.firstKey(); |
392 |
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/** |
393 |
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* Returns the last (highest) element currently in this set. |
394 |
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* |
395 |
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* @return the last (highest) element currently in this set. |
396 |
< |
* @throws NoSuchElementException sorted set is empty. |
395 |
> |
* @return the last (highest) element currently in this set |
396 |
> |
* @throws NoSuchElementException sorted set is empty |
397 |
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*/ |
398 |
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public E last() { |
399 |
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return m.lastKey(); |
403 |
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|
404 |
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/** |
405 |
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* Returns a view of the portion of this set whose elements range from |
406 |
< |
* <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>, exclusive. (If |
407 |
< |
* <tt>fromElement</tt> and <tt>toElement</tt> are equal, the returned |
406 |
> |
* {@code fromElement}, inclusive, to {@code toElement}, exclusive. (If |
407 |
> |
* {@code fromElement} and {@code toElement} are equal, the returned |
408 |
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* sorted set is empty.) The returned sorted set is backed by this set, |
409 |
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* so changes in the returned sorted set are reflected in this set, and |
410 |
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* vice-versa. |
411 |
< |
* @param fromElement low endpoint (inclusive) of the subSet. |
412 |
< |
* @param toElement high endpoint (exclusive) of the subSet. |
411 |
> |
* @param fromElement low endpoint (inclusive) of the subSet |
412 |
> |
* @param toElement high endpoint (exclusive) of the subSet |
413 |
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* @return a view of the portion of this set whose elements range from |
414 |
< |
* <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>, |
415 |
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* exclusive. |
416 |
< |
* @throws ClassCastException if <tt>fromElement</tt> and |
417 |
< |
* <tt>toElement</tt> cannot be compared to one another using |
414 |
> |
* {@code fromElement}, inclusive, to {@code toElement}, |
415 |
> |
* exclusive |
416 |
> |
* @throws ClassCastException if {@code fromElement} and |
417 |
> |
* {@code toElement} cannot be compared to one another using |
418 |
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* this set's comparator (or, if the set has no comparator, |
419 |
< |
* using natural ordering). |
420 |
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* @throws IllegalArgumentException if <tt>fromElement</tt> is |
421 |
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* greater than <tt>toElement</tt>. |
422 |
< |
* @throws NullPointerException if <tt>fromElement</tt> or |
423 |
< |
* <tt>toElement</tt> is <tt>null</tt>. |
419 |
> |
* using natural ordering) |
420 |
> |
* @throws IllegalArgumentException if {@code fromElement} is |
421 |
> |
* greater than {@code toElement} |
422 |
> |
* @throws NullPointerException if {@code fromElement} or |
423 |
> |
* {@code toElement} is {@code null} |
424 |
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*/ |
425 |
|
public NavigableSet<E> subSet(E fromElement, E toElement) { |
426 |
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return new ConcurrentSkipListSubSet<E>(m, fromElement, toElement); |
428 |
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|
429 |
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/** |
430 |
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* Returns a view of the portion of this set whose elements are strictly |
431 |
< |
* less than <tt>toElement</tt>. The returned sorted set is backed by |
431 |
> |
* less than {@code toElement}. The returned sorted set is backed by |
432 |
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* this set, so changes in the returned sorted set are reflected in this |
433 |
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* set, and vice-versa. |
434 |
< |
* @param toElement high endpoint (exclusive) of the headSet. |
434 |
> |
* @param toElement high endpoint (exclusive) of the headSet |
435 |
|
* @return a view of the portion of this set whose elements are strictly |
436 |
< |
* less than toElement. |
437 |
< |
* @throws ClassCastException if <tt>toElement</tt> is not compatible |
436 |
> |
* less than toElement |
437 |
> |
* @throws ClassCastException if {@code toElement} is not compatible |
438 |
|
* with this set's comparator (or, if the set has no comparator, |
439 |
< |
* if <tt>toElement</tt> does not implement <tt>Comparable</tt>). |
440 |
< |
* @throws NullPointerException if <tt>toElement</tt> is <tt>null</tt>. |
439 |
> |
* if {@code toElement} does not implement {@code Comparable}) |
440 |
> |
* @throws NullPointerException if {@code toElement} is {@code null} |
441 |
|
*/ |
442 |
|
public NavigableSet<E> headSet(E toElement) { |
443 |
|
return new ConcurrentSkipListSubSet<E>(m, null, toElement); |
446 |
|
|
447 |
|
/** |
448 |
|
* Returns a view of the portion of this set whose elements are |
449 |
< |
* greater than or equal to <tt>fromElement</tt>. The returned |
449 |
> |
* greater than or equal to {@code fromElement}. The returned |
450 |
|
* sorted set is backed by this set, so changes in the returned |
451 |
|
* sorted set are reflected in this set, and vice-versa. |
452 |
< |
* @param fromElement low endpoint (inclusive) of the tailSet. |
452 |
> |
* @param fromElement low endpoint (inclusive) of the tailSet |
453 |
|
* @return a view of the portion of this set whose elements are |
454 |
< |
* greater than or equal to <tt>fromElement</tt>. |
455 |
< |
* @throws ClassCastException if <tt>fromElement</tt> is not |
454 |
> |
* greater than or equal to {@code fromElement} |
455 |
> |
* @throws ClassCastException if {@code fromElement} is not |
456 |
|
* compatible with this set's comparator (or, if the set has no |
457 |
< |
* comparator, if <tt>fromElement</tt> does not implement |
458 |
< |
* <tt>Comparable</tt>). |
459 |
< |
* @throws NullPointerException if <tt>fromElement</tt> is <tt>null</tt>. |
457 |
> |
* comparator, if {@code fromElement} does not implement |
458 |
> |
* {@code Comparable}) |
459 |
> |
* @throws NullPointerException if {@code fromElement} is {@code null} |
460 |
|
*/ |
461 |
|
public NavigableSet<E> tailSet(E fromElement) { |
462 |
|
return new ConcurrentSkipListSubSet<E>(m, fromElement, null); |
469 |
|
* underlying sets, differing in that elements outside their range are |
470 |
|
* ignored, and attempts to add elements outside their ranges result |
471 |
|
* in {@link IllegalArgumentException}. Instances of this class are |
472 |
< |
* constructed only using the <tt>subSet</tt>, <tt>headSet</tt>, and |
473 |
< |
* <tt>tailSet</tt> methods of their underlying sets. |
474 |
< |
* |
472 |
> |
* constructed only using the {@code subSet}, {@code headSet}, and |
473 |
> |
* {@code tailSet} methods of their underlying sets. |
474 |
|
*/ |
475 |
|
static class ConcurrentSkipListSubSet<E> |
476 |
|
extends AbstractSet<E> |
483 |
|
|
484 |
|
/** |
485 |
|
* Creates a new submap. |
486 |
< |
* @param fromElement inclusive least value, or <tt>null</tt> if from start |
487 |
< |
* @param toElement exclusive upper bound or <tt>null</tt> if to end |
486 |
> |
* @param fromElement inclusive least value, or {@code null} if from start |
487 |
> |
* @param toElement exclusive upper bound or {@code null} if to end |
488 |
|
* @throws IllegalArgumentException if fromElement and toElement |
489 |
|
* non-null and fromElement greater than toElement |
490 |
|
*/ |