--- jsr166/src/main/java/util/TreeSet.java 2005/05/16 08:13:36 1.11
+++ jsr166/src/main/java/util/TreeSet.java 2006/04/21 03:24:07 1.23
@@ -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
@@ -49,7 +50,7 @@ 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.
@@ -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(Object)} 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(Object)} 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 super E> 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 super E> 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)