--- jsr166/src/main/java/util/TreeSet.java 2005/05/17 07:29:01 1.13
+++ jsr166/src/main/java/util/TreeSet.java 2010/09/05 21:32:19 1.31
@@ -1,8 +1,26 @@
/*
- * %W% %E%
+ * Copyright (c) 1998, 2008, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
- * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
- * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
*/
package java.util;
@@ -14,33 +32,34 @@ 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
@@ -49,34 +68,34 @@ 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
*
* @author Josh Bloch
- * @version %I%, %G%
- * @see Collection
- * @see Set
- * @see HashSet
+ * @see Collection
+ * @see Set
+ * @see HashSet
* @see Comparable
* @see Comparator
- * @see Collections#synchronizedSortedSet(SortedSet)
- * @see TreeMap
+ * @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 +103,7 @@ public class TreeSet
/**
* Constructs a set backed by the specified navigable map.
*/
- private TreeSet(NavigableMap m) {
+ TreeSet(NavigableMap m) {
this.m = m;
}
@@ -93,33 +112,33 @@ 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());
+ 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
+ * 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
- * add(Object) call will throw a ClassCastException.
+ * {@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 super E> comparator) {
- this(new TreeMap(comparator));
+ this(new TreeMap(comparator));
}
/**
@@ -127,12 +146,12 @@ public class TreeSet
* 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.
+ * 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
*/
@@ -150,7 +169,7 @@ public class TreeSet
*/
public TreeSet(SortedSet s) {
this(s.comparator());
- addAll(s);
+ addAll(s);
}
/**
@@ -159,16 +178,24 @@ public class TreeSet
* @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 in descending order.
*
* @return an iterator over the elements in this set in descending order
+ * @since 1.6
*/
public Iterator descendingIterator() {
- return m.descendingKeySet().iterator();
+ return m.descendingKeySet().iterator();
+ }
+
+ /**
+ * @since 1.6
+ */
+ public NavigableSet descendingSet() {
+ return new TreeSet(m.descendingMap());
}
/**
@@ -177,62 +204,76 @@ public class TreeSet
* @return the number of elements in this set (its cardinality)
*/
public int size() {
- return m.size();
+ return m.size();
}
/**
- * 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();
+ 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);
+ return m.containsKey(o);
}
/**
* 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;
+ return m.put(e, PRESENT)==null;
}
/**
* 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;
+ return m.remove(o)==PRESENT;
}
/**
@@ -240,14 +281,14 @@ public class TreeSet
* The set will be empty after this call returns.
*/
public void clear() {
- m.clear();
+ m.clear();
}
/**
* 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
@@ -257,7 +298,7 @@ public class TreeSet
public boolean addAll(Collection extends E> c) {
// Use linear-time version if applicable
if (m.size()==0 && c.size() > 0 &&
- c instanceof SortedSet &&
+ c instanceof SortedSet &&
m instanceof TreeMap) {
SortedSet extends E> set = (SortedSet extends E>) c;
TreeMap map = (TreeMap) m;
@@ -273,83 +314,73 @@ 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() {
@@ -374,9 +405,10 @@ 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);
@@ -384,9 +416,10 @@ 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);
@@ -394,9 +427,10 @@ 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);
@@ -404,49 +438,55 @@ 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
*/
public Object clone() {
TreeSet clone = null;
- try {
- clone = (TreeSet) super.clone();
- } catch (CloneNotSupportedException e) {
- throw new InternalError();
- }
+ try {
+ clone = (TreeSet) super.clone();
+ } catch (CloneNotSupportedException e) {
+ throw new InternalError();
+ }
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
@@ -455,8 +495,8 @@ public class TreeSet
*/
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException {
- // Write out any hidden stuff
- s.defaultWriteObject();
+ // Write out any hidden stuff
+ s.defaultWriteObject();
// Write out Comparator
s.writeObject(m.comparator());
@@ -464,30 +504,30 @@ public class TreeSet
// Write out size
s.writeInt(m.size());
- // Write out all elements in the proper order.
- for (Iterator i=m.keySet().iterator(); i.hasNext(); )
- s.writeObject(i.next());
+ // Write out all elements in the proper order.
+ for (E e : m.keySet())
+ s.writeObject(e);
}
/**
- * 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)
throws java.io.IOException, ClassNotFoundException {
- // Read in any hidden stuff
- s.defaultReadObject();
+ // Read in any hidden stuff
+ s.defaultReadObject();
// Read in Comparator
Comparator super E> c = (Comparator super E>) s.readObject();
// Create backing TreeMap
- TreeMap tm;
- if (c==null)
- tm = new TreeMap();
- else
- tm = new TreeMap(c);
- m = tm;
+ TreeMap tm;
+ if (c==null)
+ tm = new TreeMap();
+ else
+ tm = new TreeMap(c);
+ m = tm;
// Read in size
int size = s.readInt();