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revision 1.66, Sun Jan 7 07:38:27 2007 UTC revision 1.79, Sat Dec 15 22:26:29 2012 UTC
# Line 1  Line 1 
1  /*  /*
2   * %W% %E%   * Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
3     * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4   *   *
5   * Copyright 2007 Sun Microsystems, Inc. All rights reserved.   * This code is free software; you can redistribute it and/or modify it
6   * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.   * under the terms of the GNU General Public License version 2 only, as
7     * published by the Free Software Foundation.  Sun designates this
8     * particular file as subject to the "Classpath" exception as provided
9     * by Sun in the LICENSE file that accompanied this code.
10     *
11     * This code is distributed in the hope that it will be useful, but WITHOUT
12     * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13     * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14     * version 2 for more details (a copy is included in the LICENSE file that
15     * accompanied this code).
16     *
17     * You should have received a copy of the GNU General Public License version
18     * 2 along with this work; if not, write to the Free Software Foundation,
19     * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20     *
21     * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22     * or visit www.oracle.com if you need additional information or have any
23     * questions.
24   */   */
25    
26  package java.util;  package java.util;
# Line 45  Line 63 
63   * java.util.concurrent.PriorityBlockingQueue} class.   * java.util.concurrent.PriorityBlockingQueue} class.
64   *   *
65   * <p>Implementation note: this implementation provides   * <p>Implementation note: this implementation provides
66   * O(log(n)) time for the enqueing and dequeing methods   * O(log(n)) time for the enqueuing and dequeuing methods
67   * ({@code offer}, {@code poll}, {@code remove()} and {@code add});   * ({@code offer}, {@code poll}, {@code remove()} and {@code add});
68   * linear time for the {@code remove(Object)} and {@code contains(Object)}   * linear time for the {@code remove(Object)} and {@code contains(Object)}
69   * methods; and constant time for the retrieval methods   * methods; and constant time for the retrieval methods
# Line 56  Line 74 
74   * Java Collections Framework</a>.   * Java Collections Framework</a>.
75   *   *
76   * @since 1.5   * @since 1.5
  * @version %I%, %G%  
77   * @author Josh Bloch, Doug Lea   * @author Josh Bloch, Doug Lea
78   * @param <E> the type of elements held in this collection   * @param <E> the type of elements held in this collection
79   */   */
80    @SuppressWarnings("unchecked")
81  public class PriorityQueue<E> extends AbstractQueue<E>  public class PriorityQueue<E> extends AbstractQueue<E>
82      implements java.io.Serializable {      implements java.io.Serializable {
83    
# Line 153  Line 171 
171       * @throws NullPointerException if the specified collection or any       * @throws NullPointerException if the specified collection or any
172       *         of its elements are null       *         of its elements are null
173       */       */
174        @SuppressWarnings("unchecked")
175      public PriorityQueue(Collection<? extends E> c) {      public PriorityQueue(Collection<? extends E> c) {
176          initFromCollection(c);          if (c instanceof SortedSet<?>) {
177          if (c instanceof SortedSet)              SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
178              comparator = (Comparator<? super E>)              this.comparator = (Comparator<? super E>) ss.comparator();
179                  ((SortedSet<? extends E>)c).comparator();              initElementsFromCollection(ss);
180          else if (c instanceof PriorityQueue)          }
181              comparator = (Comparator<? super E>)          else if (c instanceof PriorityQueue<?>) {
182                  ((PriorityQueue<? extends E>)c).comparator();              PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
183                this.comparator = (Comparator<? super E>) pq.comparator();
184                initFromPriorityQueue(pq);
185            }
186          else {          else {
187              comparator = null;              this.comparator = null;
188              heapify();              initFromCollection(c);
189          }          }
190      }      }
191    
# Line 181  Line 203 
203       * @throws NullPointerException if the specified priority queue or any       * @throws NullPointerException if the specified priority queue or any
204       *         of its elements are null       *         of its elements are null
205       */       */
206        @SuppressWarnings("unchecked")
207      public PriorityQueue(PriorityQueue<? extends E> c) {      public PriorityQueue(PriorityQueue<? extends E> c) {
208          comparator = (Comparator<? super E>)c.comparator();          this.comparator = (Comparator<? super E>) c.comparator();
209          initFromCollection(c);          initFromPriorityQueue(c);
210      }      }
211    
212      /**      /**
# Line 199  Line 222 
222       * @throws NullPointerException if the specified sorted set or any       * @throws NullPointerException if the specified sorted set or any
223       *         of its elements are null       *         of its elements are null
224       */       */
225        @SuppressWarnings("unchecked")
226      public PriorityQueue(SortedSet<? extends E> c) {      public PriorityQueue(SortedSet<? extends E> c) {
227          comparator = (Comparator<? super E>)c.comparator();          this.comparator = (Comparator<? super E>) c.comparator();
228            initElementsFromCollection(c);
229        }
230    
231        private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
232            if (c.getClass() == PriorityQueue.class) {
233                this.queue = c.toArray();
234                this.size = c.size();
235            } else {
236          initFromCollection(c);          initFromCollection(c);
237      }      }
238        }
239    
240        private void initElementsFromCollection(Collection<? extends E> c) {
241            Object[] a = c.toArray();
242            // If c.toArray incorrectly doesn't return Object[], copy it.
243            if (a.getClass() != Object[].class)
244                a = Arrays.copyOf(a, a.length, Object[].class);
245            int len = a.length;
246            if (len == 1 || this.comparator != null)
247                for (int i = 0; i < len; i++)
248                    if (a[i] == null)
249                        throw new NullPointerException();
250            this.queue = a;
251            this.size = a.length;
252        }
253    
254      /**      /**
255       * Initializes queue array with elements from the given Collection.       * Initializes queue array with elements from the given Collection.
# Line 210  Line 257 
257       * @param c the collection       * @param c the collection
258       */       */
259      private void initFromCollection(Collection<? extends E> c) {      private void initFromCollection(Collection<? extends E> c) {
260          Object[] a = c.toArray();          initElementsFromCollection(c);
261          // If c.toArray incorrectly doesn't return Object[], copy it.          heapify();
         if (a.getClass() != Object[].class)  
             a = Arrays.copyOf(a, a.length, Object[].class);  
         queue = a;  
         size = a.length;  
262      }      }
263    
264      /**      /**
265         * The maximum size of array to allocate.
266         * Some VMs reserve some header words in an array.
267         * Attempts to allocate larger arrays may result in
268         * OutOfMemoryError: Requested array size exceeds VM limit
269         */
270        private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
271    
272        /**
273       * Increases the capacity of the array.       * Increases the capacity of the array.
274       *       *
275       * @param minCapacity the desired minimum capacity       * @param minCapacity the desired minimum capacity
276       */       */
277      private void grow(int minCapacity) {      private void grow(int minCapacity) {
         if (minCapacity < 0) // overflow  
             throw new OutOfMemoryError();  
278          int oldCapacity = queue.length;          int oldCapacity = queue.length;
279          // Double size if small; else grow by 50%          // Double size if small; else grow by 50%
280          int newCapacity = ((oldCapacity < 64)?          int newCapacity = oldCapacity + ((oldCapacity < 64) ?
281                             ((oldCapacity + 1) * 2):                                           (oldCapacity + 2) :
282                             ((oldCapacity / 2) * 3));                                           (oldCapacity >> 1));
283          if (newCapacity < 0) // overflow          // overflow-conscious code
284              newCapacity = Integer.MAX_VALUE;          if (newCapacity - MAX_ARRAY_SIZE > 0)
285          if (newCapacity < minCapacity)              newCapacity = hugeCapacity(minCapacity);
             newCapacity = minCapacity;  
286          queue = Arrays.copyOf(queue, newCapacity);          queue = Arrays.copyOf(queue, newCapacity);
287      }      }
288    
289        private static int hugeCapacity(int minCapacity) {
290            if (minCapacity < 0) // overflow
291                throw new OutOfMemoryError();
292            return (minCapacity > MAX_ARRAY_SIZE) ?
293                Integer.MAX_VALUE :
294                MAX_ARRAY_SIZE;
295        }
296    
297      /**      /**
298       * Inserts the specified element into this priority queue.       * Inserts the specified element into this priority queue.
299       *       *
# Line 276  Line 332 
332      }      }
333    
334      public E peek() {      public E peek() {
335          if (size == 0)          return (size == 0) ? null : (E) queue[0];
             return null;  
         return (E) queue[0];  
336      }      }
337    
338      private int indexOf(Object o) {      private int indexOf(Object o) {
# Line 379  Line 433 
433       * The following code can be used to dump the queue into a newly       * The following code can be used to dump the queue into a newly
434       * allocated array of <tt>String</tt>:       * allocated array of <tt>String</tt>:
435       *       *
436       * <pre>       *  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
      *     String[] y = x.toArray(new String[0]);</pre>  
437       *       *
438       * Note that <tt>toArray(new Object[0])</tt> is identical in function to       * Note that <tt>toArray(new Object[0])</tt> is identical in function to
439       * <tt>toArray()</tt>.       * <tt>toArray()</tt>.
# Line 537  Line 590 
590       * avoid missing traversing elements.       * avoid missing traversing elements.
591       */       */
592      private E removeAt(int i) {      private E removeAt(int i) {
593          assert i >= 0 && i < size;          // assert i >= 0 && i < size;
594          modCount++;          modCount++;
595          int s = --size;          int s = --size;
596          if (s == i) // removed last element          if (s == i) // removed last element
# Line 672  Line 725 
725      }      }
726    
727      /**      /**
728       * Saves the state of the instance to a stream (that       * Saves this queue to a stream (that is, serializes it).
      * is, serializes it).  
729       *       *
730       * @serialData The length of the array backing the instance is       * @serialData The length of the array backing the instance is
731       *             emitted (int), followed by all of its elements       *             emitted (int), followed by all of its elements
732       *             (each an {@code Object}) in the proper order.       *             (each an {@code Object}) in the proper order.
      * @param s the stream  
733       */       */
734      private void writeObject(java.io.ObjectOutputStream s)      private void writeObject(java.io.ObjectOutputStream s)
735          throws java.io.IOException{          throws java.io.IOException{
# Line 694  Line 745 
745      }      }
746    
747      /**      /**
748       * Reconstitutes the {@code PriorityQueue} instance from a stream       * Reconstitutes this queue from a stream (that is, deserializes it).
      * (that is, deserializes it).  
      *  
      * @param s the stream  
749       */       */
750      private void readObject(java.io.ObjectInputStream s)      private void readObject(java.io.ObjectInputStream s)
751          throws java.io.IOException, ClassNotFoundException {          throws java.io.IOException, ClassNotFoundException {

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