--- jsr166/src/main/java/util/TreeSet.java 2005/05/16 08:13:36 1.11 +++ jsr166/src/main/java/util/TreeSet.java 2006/05/09 21:55:10 1.24 @@ -1,7 +1,7 @@ /* * %W% %E% * - * Copyright 2005 Sun Microsystems, Inc. All rights reserved. + * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ @@ -14,33 +14,34 @@ package java.util; * time, depending on which constructor is used. * *

This implementation provides guaranteed log(n) time cost for the basic - * operations (add, remove and contains). + * operations ({@code add}, {@code remove} and {@code contains}). * *

Note that the ordering maintained by a set (whether or not an explicit * comparator is provided) must be consistent with equals if it is to - * correctly implement the Set interface. (See Comparable - * or Comparator for a precise definition of consistent with - * equals.) This is so because the Set interface is defined in - * terms of the equals operation, but a TreeSet instance - * performs all element comparisons using its compareTo (or - * compare) method, so two elements that are deemed equal by this method + * correctly implement the {@code Set} interface. (See {@code Comparable} + * or {@code Comparator} for a precise definition of consistent with + * equals.) This is so because the {@code Set} interface is defined in + * terms of the {@code equals} operation, but a {@code TreeSet} instance + * performs all element comparisons using its {@code compareTo} (or + * {@code compare}) method, so two elements that are deemed equal by this method * are, from the standpoint of the set, equal. The behavior of a set * is well-defined even if its ordering is inconsistent with equals; it - * just fails to obey the general contract of the Set interface. + * just fails to obey the general contract of the {@code Set} interface. * - *

Note that this implementation is not synchronized. If multiple - * threads access a set concurrently, and at least one of the threads modifies - * the set, it must be synchronized externally. This is typically - * accomplished by synchronizing on some object that naturally encapsulates - * the set. If no such object exists, the set should be "wrapped" using the - * Collections.synchronizedSet method. This is best done at creation - * time, to prevent accidental unsynchronized access to the set: 

- *     SortedSet s = Collections.synchronizedSortedSet(new TreeSet(...));
- *
+ *

Note that this implementation is not synchronized. + * If multiple threads access a tree set concurrently, and at least one + * of the threads modifies the set, it must be synchronized + * externally. This is typically accomplished by synchronizing on some + * object that naturally encapsulates the set. + * If no such object exists, the set should be "wrapped" using the + * {@link Collections#synchronizedSortedSet Collections.synchronizedSortedSet} + * method. This is best done at creation time, to prevent accidental + * unsynchronized access to the set: 

+ *   SortedSet s = Collections.synchronizedSortedSet(new TreeSet(...));
* - *

The iterators returned by this class's iterator method are + *

The iterators returned by this class's {@code iterator} method are * fail-fast: if the set is modified at any time after the iterator is - * created, in any way except through the iterator's own remove + * created, in any way except through the iterator's own {@code remove} * method, the iterator will throw a {@link ConcurrentModificationException}. * Thus, in the face of concurrent modification, the iterator fails quickly * and cleanly, rather than risking arbitrary, non-deterministic behavior at @@ -49,13 +50,13 @@ package java.util; *

Note that the fail-fast behavior of an iterator cannot be guaranteed * as it is, generally speaking, impossible to make any hard guarantees in the * presence of unsynchronized concurrent modification. Fail-fast iterators - * throw ConcurrentModificationException on a best-effort basis. + * throw {@code ConcurrentModificationException} on a best-effort basis. * Therefore, it would be wrong to write a program that depended on this * exception for its correctness: the fail-fast behavior of iterators * should be used only to detect bugs. * *

This class is a member of the - * + * * Java Collections Framework. * * @param the type of elements maintained by this set @@ -67,16 +68,17 @@ package java.util; * @see HashSet * @see Comparable * @see Comparator - * @see Collections#synchronizedSortedSet(SortedSet) * @see TreeMap * @since 1.2 */ -public class TreeSet - extends AbstractSet +public class TreeSet extends AbstractSet implements NavigableSet, Cloneable, java.io.Serializable { - private transient NavigableMap m; // The backing Map + /** + * The backing map. + */ + private transient NavigableMap m; // Dummy value to associate with an Object in the backing Map private static final Object PRESENT = new Object(); @@ -84,7 +86,7 @@ public class TreeSet /** * Constructs a set backed by the specified navigable map. */ - private TreeSet(NavigableMap m) { + TreeSet(NavigableMap m) { this.m = m; } @@ -93,31 +95,29 @@ public class TreeSet * natural ordering of its elements. All elements inserted into * the set must implement the {@link Comparable} interface. * Furthermore, all such elements must be mutually - * comparable: e1.compareTo(e2) must not throw a - * ClassCastException for any elements e1 and - * e2 in the set. If the user attempts to add an element + * comparable: {@code e1.compareTo(e2)} must not throw a + * {@code ClassCastException} for any elements {@code e1} and + * {@code e2} in the set. If the user attempts to add an element * to the set that violates this constraint (for example, the user * attempts to add a string element to a set whose elements are - * integers), the add(Object) call will throw a - * ClassCastException. + * integers), the {@code add} call will throw a + * {@code ClassCastException}. */ public TreeSet() { this(new TreeMap()); } /** - * Constructs a new, empty tree set, sorted according to the - * specified comparator. All elements inserted into the set must - * be mutually comparable by the specified comparator: - * comparator.compare(e1, e2) must not throw a - * ClassCastException for any elements e1 and - * e2 in the set. If the user attempts to add an element - * to the set that violates this constraint, the - * add(Object) call will throw a - * ClassCastException. + * Constructs a new, empty tree set, sorted according to the specified + * comparator. All elements inserted into the set must be mutually + * comparable by the specified comparator: {@code comparator.compare(e1, + * e2)} must not throw a {@code ClassCastException} for any elements + * {@code e1} and {@code e2} in the set. If the user attempts to add + * an element to the set that violates this constraint, the + * {@code add} call will throw a {@code ClassCastException}. * * @param comparator the comparator that will be used to order this set. - * If null, the {@linkplain Comparable natural + * If {@code null}, the {@linkplain Comparable natural * ordering} of the elements will be used. */ public TreeSet(Comparator comparator) { @@ -125,17 +125,16 @@ public class TreeSet } /** - * Constructs a new tree set containing the elements in the - * specified collection, sorted according to the natural - * ordering of its elements. All elements inserted into the - * set must implement the {@link Comparable} interface. - * Furthermore, all such elements must be mutually - * comparable: e1.compareTo(e2) must not throw a - * ClassCastException for any elements e1 and - * e2 in the set. + * Constructs a new tree set containing the elements in the specified + * collection, sorted according to the natural ordering of its + * elements. All elements inserted into the set must implement the + * {@link Comparable} interface. Furthermore, all such elements must be + * mutually comparable: {@code e1.compareTo(e2)} must not throw a + * {@code ClassCastException} for any elements {@code e1} and + * {@code e2} in the set. * * @param c collection whose elements will comprise the new set - * @throws ClassCastException if the elements in c are + * @throws ClassCastException if the elements in {@code c} are * not {@link Comparable}, or are not mutually comparable * @throws NullPointerException if the specified collection is null */ @@ -157,26 +156,32 @@ public class TreeSet } /** - * Returns an iterator over the elements in this set. The elements - * are returned in ascending order. + * Returns an iterator over the elements in this set in ascending order. * - * @return an iterator over the elements in this set + * @return an iterator over the elements in this set in ascending order */ public Iterator iterator() { - return m.keySet().iterator(); + return m.navigableKeySet().iterator(); } /** - * Returns an iterator over the elements in this set. The elements - * are returned in descending order. + * Returns an iterator over the elements in this set in descending order. * - * @return an iterator over the elements in this set + * @return an iterator over the elements in this set in descending order + * @since 1.6 */ public Iterator descendingIterator() { return m.descendingKeySet().iterator(); } /** + * @since 1.6 + */ + public NavigableSet descendingSet() { + return new TreeSet(m.descendingMap()); + } + + /** * Returns the number of elements in this set (its cardinality). * * @return the number of elements in this set (its cardinality) @@ -186,24 +191,27 @@ public class TreeSet } /** - * Returns true if this set contains no elements. + * Returns {@code true} if this set contains no elements. * - * @return true if this set contains no elements + * @return {@code true} if this set contains no elements */ public boolean isEmpty() { return m.isEmpty(); } /** - * Returns true if this set contains the specified element. + * Returns {@code true} if this set contains the specified element. + * More formally, returns {@code true} if and only if this set + * contains an element {@code e} such that + * (o==null ? e==null : o.equals(e)). * - * @param o the object to be checked for containment in this set - * @return true if this set contains the specified element + * @param o object to be checked for containment in this set + * @return {@code true} if this set contains the specified element * @throws ClassCastException if the specified object cannot be compared * with the elements currently in the set - * @throws NullPointerException if the specified element is null and - * this set uses natural ordering and is non-empty, or its - * comparator does not permit null elements + * @throws NullPointerException if the specified element is null + * and this set uses natural ordering, or its comparator + * does not permit null elements */ public boolean contains(Object o) { return m.containsKey(o); @@ -211,15 +219,20 @@ public class TreeSet /** * Adds the specified element to this set if it is not already present. + * More formally, adds the specified element {@code e} to this set if + * the set contains no element {@code e2} such that + * (e==null ? e2==null : e.equals(e2)). + * If this set already contains the element, the call leaves the set + * unchanged and returns {@code false}. * * @param e element to be added to this set - * @return true if the set did not already contain the specified + * @return {@code true} if this set did not already contain the specified * element * @throws ClassCastException if the specified object cannot be compared - * with the elements currently in the set - * @throws NullPointerException if the specified element is null and - * this set uses natural ordering and is non-empty, or its - * comparator does not permit null elements + * with the elements currently in this set + * @throws NullPointerException if the specified element is null + * and this set uses natural ordering, or its comparator + * does not permit null elements */ public boolean add(E e) { return m.put(e, PRESENT)==null; @@ -227,14 +240,20 @@ public class TreeSet /** * Removes the specified element from this set if it is present. + * More formally, removes an element {@code e} such that + * (o==null ? e==null : o.equals(e)), + * if this set contains such an element. Returns {@code true} if + * this set contained the element (or equivalently, if this set + * changed as a result of the call). (This set will not contain the + * element once the call returns.) * * @param o object to be removed from this set, if present - * @return true if the set contained the specified element + * @return {@code true} if this set contained the specified element * @throws ClassCastException if the specified object cannot be compared - * with the elements currently in the set - * @throws NullPointerException if the specified element is null and - * this set uses natural ordering and is non-empty, or its - * comparator does not permit null elements + * with the elements currently in this set + * @throws NullPointerException if the specified element is null + * and this set uses natural ordering, or its comparator + * does not permit null elements */ public boolean remove(Object o) { return m.remove(o)==PRESENT; @@ -251,8 +270,8 @@ public class TreeSet /** * Adds all of the elements in the specified collection to this set. * - * @param c elements to be added - * @return true if this set changed as a result of the call + * @param c collection containing elements to be added to this set + * @return {@code true} if this set changed as a result of the call * @throws ClassCastException if the elements provided cannot be compared * with the elements currently in the set * @throws NullPointerException if the specified collection is null or @@ -278,83 +297,73 @@ public class TreeSet /** * @throws ClassCastException {@inheritDoc} - * @throws NullPointerException if fromElement or - * toElement is null and this set uses natural ordering, - * or its comparator does not permit null elements + * @throws NullPointerException if {@code fromElement} or {@code toElement} + * is null and this set uses natural ordering, or its comparator + * does not permit null elements * @throws IllegalArgumentException {@inheritDoc} + * @since 1.6 */ - public NavigableSet navigableSubSet(E fromElement, E toElement) { - return new TreeSet(m.navigableSubMap(fromElement, toElement)); + public NavigableSet subSet(E fromElement, boolean fromInclusive, + E toElement, boolean toInclusive) { + return new TreeSet(m.subMap(fromElement, fromInclusive, + toElement, toInclusive)); } /** * @throws ClassCastException {@inheritDoc} - * @throws NullPointerException if toElement is null and + * @throws NullPointerException if {@code toElement} is null and * this set uses natural ordering, or its comparator does * not permit null elements * @throws IllegalArgumentException {@inheritDoc} + * @since 1.6 */ - public NavigableSet navigableHeadSet(E toElement) { - return new TreeSet(m.navigableHeadMap(toElement)); + public NavigableSet headSet(E toElement, boolean inclusive) { + return new TreeSet(m.headMap(toElement, inclusive)); } /** * @throws ClassCastException {@inheritDoc} - * @throws NullPointerException if fromElement is null and + * @throws NullPointerException if {@code fromElement} is null and * this set uses natural ordering, or its comparator does * not permit null elements * @throws IllegalArgumentException {@inheritDoc} + * @since 1.6 */ - public NavigableSet navigableTailSet(E fromElement) { - return new TreeSet(m.navigableTailMap(fromElement)); + public NavigableSet tailSet(E fromElement, boolean inclusive) { + return new TreeSet(m.tailMap(fromElement, inclusive)); } /** - * Equivalent to {@link #navigableSubSet} but with a return type - * conforming to the SortedSet interface. - * - *

{@inheritDoc} - * * @throws ClassCastException {@inheritDoc} - * @throws NullPointerException if fromElement or - * toElement is null and this set uses natural ordering, + * @throws NullPointerException if {@code fromElement} or + * {@code toElement} is null and this set uses natural ordering, * or its comparator does not permit null elements * @throws IllegalArgumentException {@inheritDoc} */ public SortedSet subSet(E fromElement, E toElement) { - return new TreeSet(m.navigableSubMap(fromElement, toElement)); + return subSet(fromElement, true, toElement, false); } /** - * Equivalent to {@link #navigableHeadSet} but with a return type - * conforming to the SortedSet interface. - * - *

{@inheritDoc} - * * @throws ClassCastException {@inheritDoc} - * @throws NullPointerException if toElement is null + * @throws NullPointerException if {@code toElement} is null * and this set uses natural ordering, or its comparator does * not permit null elements * @throws IllegalArgumentException {@inheritDoc} */ public SortedSet headSet(E toElement) { - return new TreeSet(m.navigableHeadMap(toElement)); + return headSet(toElement, false); } /** - * Equivalent to {@link #navigableTailSet} but with a return type - * conforming to the SortedSet interface. - * - *

{@inheritDoc} - * * @throws ClassCastException {@inheritDoc} - * @throws NullPointerException if fromElement is null + * @throws NullPointerException if {@code fromElement} is null * and this set uses natural ordering, or its comparator does * not permit null elements * @throws IllegalArgumentException {@inheritDoc} */ public SortedSet tailSet(E fromElement) { - return new TreeSet(m.navigableTailMap(fromElement)); + return tailSet(fromElement, true); } public Comparator comparator() { @@ -379,9 +388,10 @@ public class TreeSet /** * @throws ClassCastException {@inheritDoc} - * @throws NullPointerException if the specified element is null and - * this set uses natural ordering and is non-empty, - * or its comparator does not permit null elements + * @throws NullPointerException if the specified element is null + * and this set uses natural ordering, or its comparator + * does not permit null elements + * @since 1.6 */ public E lower(E e) { return m.lowerKey(e); @@ -389,9 +399,10 @@ public class TreeSet /** * @throws ClassCastException {@inheritDoc} - * @throws NullPointerException if the specified element is null and - * this set uses natural ordering and is non-empty, - * or its comparator does not permit null elements + * @throws NullPointerException if the specified element is null + * and this set uses natural ordering, or its comparator + * does not permit null elements + * @since 1.6 */ public E floor(E e) { return m.floorKey(e); @@ -399,9 +410,10 @@ public class TreeSet /** * @throws ClassCastException {@inheritDoc} - * @throws NullPointerException if the specified element is null and - * this set uses natural ordering and is non-empty, - * or its comparator does not permit null elements + * @throws NullPointerException if the specified element is null + * and this set uses natural ordering, or its comparator + * does not permit null elements + * @since 1.6 */ public E ceiling(E e) { return m.ceilingKey(e); @@ -409,26 +421,33 @@ public class TreeSet /** * @throws ClassCastException {@inheritDoc} - * @throws NullPointerException if the specified element is null and - * this set uses natural ordering and is non-empty, - * or its comparator does not permit null elements + * @throws NullPointerException if the specified element is null + * and this set uses natural ordering, or its comparator + * does not permit null elements + * @since 1.6 */ public E higher(E e) { return m.higherKey(e); } + /** + * @since 1.6 + */ public E pollFirst() { Map.Entry e = m.pollFirstEntry(); return (e == null)? null : e.getKey(); } + /** + * @since 1.6 + */ public E pollLast() { Map.Entry e = m.pollLastEntry(); return (e == null)? null : e.getKey(); } /** - * Returns a shallow copy of this TreeSet instance. (The elements + * Returns a shallow copy of this {@code TreeSet} instance. (The elements * themselves are not cloned.) * * @return a shallow copy of this set @@ -442,16 +461,15 @@ public class TreeSet } clone.m = new TreeMap(m); - return clone; } /** - * Save the state of the TreeSet instance to a stream (that is, + * Save the state of the {@code TreeSet} instance to a stream (that is, * serialize it). * * @serialData Emits the comparator used to order this set, or - * null if it obeys its elements' natural ordering + * {@code null} if it obeys its elements' natural ordering * (Object), followed by the size of the set (the number of * elements it contains) (int), followed by all of its * elements (each an Object) in order (as determined by the @@ -475,7 +493,7 @@ public class TreeSet } /** - * Reconstitute the TreeSet instance from a stream (that is, + * Reconstitute the {@code TreeSet} instance from a stream (that is, * deserialize it). */ private void readObject(java.io.ObjectInputStream s)