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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.56 by jsr166, Mon Nov 28 02:35:46 2005 UTC vs.
Revision 1.78 by jsr166, Sun Nov 18 18:03:10 2012 UTC

#	Line 1 | Line 1
1		/*
2	<	* @(#)PriorityQueue.java       1.8 05/08/27
2	>	* 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 2005 Sun Microsystems, Inc. All rights reserved.
6	<	* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
5	>	* This code is free software; you can redistribute it and/or modify it
6	>	* 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;
9	–	import java.util.*; // for javadoc (till 6280605 is fixed)
27
28		/**
29	<	* An unbounded priority {@linkplain Queue queue} based on a priority
30	<	* heap.  The elements of the priority queue are ordered according to
31	<	* their {@linkplain Comparable natural ordering}, or by a {@link
32	<	* Comparator} provided at queue construction time, depending on which
33	<	* constructor is used.  A priority queue does not permit
34	<	* <tt>null</tt> elements.  A priority queue relying on natural
35	<	* ordering also does not permit insertion of non-comparable objects
36	<	* (doing so may result in <tt>ClassCastException</tt>).
29	>	* An unbounded priority {@linkplain Queue queue} based on a priority heap.
30	>	* The elements of the priority queue are ordered according to their
31	>	* {@linkplain Comparable natural ordering}, or by a {@link Comparator}
32	>	* provided at queue construction time, depending on which constructor is
33	>	* used.  A priority queue does not permit {@code null} elements.
34	>	* A priority queue relying on natural ordering also does not permit
35	>	* insertion of non-comparable objects (doing so may result in
36	>	* {@code ClassCastException}).
37		*
38		* <p>The <em>head</em> of this queue is the <em>least</em> element
39		* with respect to the specified ordering.  If multiple elements are
40		* tied for least value, the head is one of those elements -- ties are
41	<	* broken arbitrarily.  The queue retrieval operations <tt>poll</tt>,
42	<	* <tt>remove</tt>, <tt>peek</tt>, and <tt>element</tt> access the
41	>	* broken arbitrarily.  The queue retrieval operations {@code poll},
42	>	* {@code remove}, {@code peek}, and {@code element} access the
43		* element at the head of the queue.
44		*
45		* <p>A priority queue is unbounded, but has an internal
#	Line 37 | Line 54 | import java.util.*; // for javadoc (till
54		* Iterator} interfaces.  The Iterator provided in method {@link
55		* #iterator()} is <em>not</em> guaranteed to traverse the elements of
56		* the priority queue in any particular order. If you need ordered
57	<	* traversal, consider using <tt>Arrays.sort(pq.toArray())</tt>.
57	>	* traversal, consider using {@code Arrays.sort(pq.toArray())}.
58		*
59	<	* <p> <strong>Note that this implementation is not synchronized.</strong>
60	<	* Multiple threads should not access a <tt>PriorityQueue</tt>
61	<	* instance concurrently if any of the threads modifies the list
62	<	* structurally. Instead, use the thread-safe {@link
59	>	* <p><strong>Note that this implementation is not synchronized.</strong>
60	>	* Multiple threads should not access a {@code PriorityQueue}
61	>	* instance concurrently if any of the threads modifies the queue.
62	>	* Instead, use the thread-safe {@link
63		* java.util.concurrent.PriorityBlockingQueue} class.
64		*
65	<	* <p>Implementation note: this implementation provides O(log(n)) time
66	<	* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>,
67	<	* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the
68	<	* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and
69	<	* constant time for the retrieval methods (<tt>peek</tt>,
70	<	* <tt>element</tt>, and <tt>size</tt>).
65	>	* <p>Implementation note: this implementation provides
66	>	* O(log(n)) time for the enqueing and dequeing methods
67	>	* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
68	>	* linear time for the {@code remove(Object)} and {@code contains(Object)}
69	>	* methods; and constant time for the retrieval methods
70	>	* ({@code peek}, {@code element}, and {@code size}).
71		*
72		* <p>This class is a member of the
73	<	* <a href="{@docRoot}/../guide/collections/index.html">
73	>	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
74		* Java Collections Framework</a>.
75	+	*
76		* @since 1.5
77	<	* @version 1.8, 08/27/05
60	<	* @author Josh Bloch
77	>	* @author Josh Bloch, Doug Lea
78		* @param <E> the type of elements held in this collection
79		*/
80	+	@SuppressWarnings("unchecked")
81		public class PriorityQueue<E> extends AbstractQueue<E>
82		implements java.io.Serializable {
83
#	Line 95 | Line 113 | public class PriorityQueue<E> extends Ab
113		private transient int modCount = 0;
114
115		/**
116	<	* Creates a <tt>PriorityQueue</tt> with the default initial
116	>	* Creates a {@code PriorityQueue} with the default initial
117		* capacity (11) that orders its elements according to their
118		* {@linkplain Comparable natural ordering}.
119		*/
#	Line 104 | Line 122 | public class PriorityQueue<E> extends Ab
122		}
123
124		/**
125	<	* Creates a <tt>PriorityQueue</tt> with the specified initial
125	>	* Creates a {@code PriorityQueue} with the specified initial
126		* capacity that orders its elements according to their
127		* {@linkplain Comparable natural ordering}.
128		*
129		* @param initialCapacity the initial capacity for this priority queue
130	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
131	<	* than 1
130	>	* @throws IllegalArgumentException if {@code initialCapacity} is less
131	>	*         than 1
132		*/
133		public PriorityQueue(int initialCapacity) {
134		this(initialCapacity, null);
135		}
136
137		/**
138	<	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
138	>	* Creates a {@code PriorityQueue} with the specified initial capacity
139		* that orders its elements according to the specified comparator.
140		*
141		* @param  initialCapacity the initial capacity for this priority queue
142	<	* @param  comparator the comparator that will be used to order
143	<	*         this priority queue.  If <tt>null</tt>, the <i>natural
144	<	*         ordering</i> of the elements will be used.
145	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is
142	>	* @param  comparator the comparator that will be used to order this
143	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
144	>	*         natural ordering} of the elements will be used.
145	>	* @throws IllegalArgumentException if {@code initialCapacity} is
146		*         less than 1
147		*/
148		public PriorityQueue(int initialCapacity,
#	Line 138 | Line 156 | public class PriorityQueue<E> extends Ab
156		}
157
158		/**
159	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
160	<	* specified collection.   If the specified collection is an
161	<	* instance of a {@link java.util.SortedSet} or is another
162	<	* <tt>PriorityQueue</tt>, the priority queue will be ordered
163	<	* according to the same ordering.  Otherwise, this priority queue
164	<	* will be ordered according to the natural ordering of its elements.
159	>	* Creates a {@code PriorityQueue} containing the elements in the
160	>	* specified collection.  If the specified collection is an instance of
161	>	* a {@link SortedSet} or is another {@code PriorityQueue}, this
162	>	* priority queue will be ordered according to the same ordering.
163	>	* Otherwise, this priority queue will be ordered according to the
164	>	* {@linkplain Comparable natural ordering} of its elements.
165		*
166		* @param  c the collection whose elements are to be placed
167		*         into this priority queue
#	Line 153 | Line 171 | public class PriorityQueue<E> extends Ab
171		* @throws NullPointerException if the specified collection or any
172		*         of its elements are null
173		*/
174	+	@SuppressWarnings("unchecked")
175		public PriorityQueue(Collection<? extends E> c) {
176	<	initFromCollection(c);
177	<	if (c instanceof SortedSet)
178	<	comparator = (Comparator<? super E>)
179	<	((SortedSet<? extends E>)c).comparator();
180	<	else if (c instanceof PriorityQueue)
181	<	comparator = (Comparator<? super E>)
182	<	((PriorityQueue<? extends E>)c).comparator();
176	>	if (c instanceof SortedSet<?>) {
177	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
178	>	this.comparator = (Comparator<? super E>) ss.comparator();
179	>	initElementsFromCollection(ss);
180	>	}
181	>	else if (c instanceof PriorityQueue<?>) {
182	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
183	>	this.comparator = (Comparator<? super E>) pq.comparator();
184	>	initFromPriorityQueue(pq);
185	>	}
186		else {
187	<	comparator = null;
188	<	heapify();
187	>	this.comparator = null;
188	>	initFromCollection(c);
189		}
190		}
191
192		/**
193	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
193	>	* Creates a {@code PriorityQueue} containing the elements in the
194		* specified priority queue.  This priority queue will be
195		* ordered according to the same ordering as the given priority
196		* queue.
197		*
198		* @param  c the priority queue whose elements are to be placed
199		*         into this priority queue
200	<	* @throws ClassCastException if elements of <tt>c</tt> cannot be
201	<	*         compared to one another according to <tt>c</tt>'s
200	>	* @throws ClassCastException if elements of {@code c} cannot be
201	>	*         compared to one another according to {@code c}'s
202		*         ordering
203		* @throws NullPointerException if the specified priority queue or any
204		*         of its elements are null
205		*/
206	+	@SuppressWarnings("unchecked")
207		public PriorityQueue(PriorityQueue<? extends E> c) {
208	<	comparator = (Comparator<? super E>)c.comparator();
209	<	initFromCollection(c);
208	>	this.comparator = (Comparator<? super E>) c.comparator();
209	>	initFromPriorityQueue(c);
210		}
211
212		/**
213	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
214	<	* specified sorted set.  This priority queue will be ordered
213	>	* Creates a {@code PriorityQueue} containing the elements in the
214	>	* specified sorted set.   This priority queue will be ordered
215		* according to the same ordering as the given sorted set.
216		*
217		* @param  c the sorted set whose elements are to be placed
218	<	*         into this priority queue.
218	>	*         into this priority queue
219		* @throws ClassCastException if elements of the specified sorted
220		*         set cannot be compared to one another according to the
221		*         sorted set's ordering
222		* @throws NullPointerException if the specified sorted set or any
223		*         of its elements are null
224		*/
225	+	@SuppressWarnings("unchecked")
226		public PriorityQueue(SortedSet<? extends E> c) {
227	<	comparator = (Comparator<? super E>)c.comparator();
228	<	initFromCollection(c);
227	>	this.comparator = (Comparator<? super E>) c.comparator();
228	>	initElementsFromCollection(c);
229		}
230
231	<	/**
232	<	* Initialize queue array with elements from the given Collection.
233	<	* @param c the collection
234	<	*/
235	<	private void initFromCollection(Collection<? extends E> c) {
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);
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	<	queue = a;
246	<	size = a.length;
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.
256	+	*
257	+	* @param c the collection
258	+	*/
259	+	private void initFromCollection(Collection<? extends E> c) {
260	+	initElementsFromCollection(c);
261	+	heapify();
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.
274		*
275		* @param minCapacity the desired minimum capacity
276		*/
277		private void grow(int minCapacity) {
278	<	if (minCapacity < 0) // overflow
227	<	throw new OutOfMemoryError();
228	<	int oldCapacity = queue.length;
278	>	int oldCapacity = queue.length;
279		// Double size if small; else grow by 50%
280	<	int newCapacity = ((oldCapacity < 64)?
281	<	((oldCapacity + 1) * 2):
282	<	((oldCapacity * 3) / 2));
283	<	if (newCapacity < minCapacity)
284	<	newCapacity = minCapacity;
280	>	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
281	>	(oldCapacity + 2) :
282	>	(oldCapacity >> 1));
283	>	// overflow-conscious code
284	>	if (newCapacity - MAX_ARRAY_SIZE > 0)
285	>	newCapacity = hugeCapacity(minCapacity);
286		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.
299		*
300	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
300	>	* @return {@code true} (as specified by {@link Collection#add})
301		* @throws ClassCastException if the specified element cannot be
302		*         compared with elements currently in this priority queue
303		*         according to the priority queue's ordering
#	Line 251 | Line 310 | public class PriorityQueue<E> extends Ab
310		/**
311		* Inserts the specified element into this priority queue.
312		*
313	<	* @return <tt>true</tt> (as specified by {@link Queue#offer})
313	>	* @return {@code true} (as specified by {@link Queue#offer})
314		* @throws ClassCastException if the specified element cannot be
315		*         compared with elements currently in this priority queue
316		*         according to the priority queue's ordering
#	Line 273 | Line 332 | public class PriorityQueue<E> extends Ab
332		}
333
334		public E peek() {
335	<	if (size == 0)
277	<	return null;
278	<	return (E) queue[0];
335	>	return (size == 0) ? null : (E) queue[0];
336		}
337
338		private int indexOf(Object o) {
339	<	if (o != null) {
339	>	if (o != null) {
340		for (int i = 0; i < size; i++)
341		if (o.equals(queue[i]))
342		return i;
#	Line 289 | Line 346 | public class PriorityQueue<E> extends Ab
346
347		/**
348		* Removes a single instance of the specified element from this queue,
349	<	* if it is present.  More formally, removes an element <tt>e</tt> such
350	<	* that <tt>o.equals(e)</tt>, if this queue contains one or more such
351	<	* elements.  Returns true if this queue contained the specified element
352	<	* (or equivalently, if this queue changed as a result of the call).
349	>	* if it is present.  More formally, removes an element {@code e} such
350	>	* that {@code o.equals(e)}, if this queue contains one or more such
351	>	* elements.  Returns {@code true} if and only if this queue contained
352	>	* the specified element (or equivalently, if this queue changed as a
353	>	* result of the call).
354		*
355		* @param o element to be removed from this queue, if present
356	<	* @return <tt>true</tt> if this queue changed as a result of the call
356	>	* @return {@code true} if this queue changed as a result of the call
357		*/
358		public boolean remove(Object o) {
359	<	int i = indexOf(o);
360	<	if (i == -1)
361	<	return false;
362	<	else {
363	<	removeAt(i);
364	<	return true;
365	<	}
359	>	int i = indexOf(o);
360	>	if (i == -1)
361	>	return false;
362	>	else {
363	>	removeAt(i);
364	>	return true;
365	>	}
366		}
367
368		/**
369		* Version of remove using reference equality, not equals.
370	<	* Needed by iterator.remove
370	>	* Needed by iterator.remove.
371		*
372		* @param o element to be removed from this queue, if present
373	<	* @return <tt>true</tt> if removed.
373	>	* @return {@code true} if removed
374		*/
375		boolean removeEq(Object o) {
376	<	for (int i = 0; i < size; i++) {
377	<	if (o == queue[i]) {
376	>	for (int i = 0; i < size; i++) {
377	>	if (o == queue[i]) {
378		removeAt(i);
379		return true;
380		}
#	Line 325 | Line 383 | public class PriorityQueue<E> extends Ab
383		}
384
385		/**
386	<	* Returns <tt>true</tt> if this queue contains the specified element.
387	<	* More formally, returns <tt>true</tt> if and only if this queue contains
388	<	* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
386	>	* Returns {@code true} if this queue contains the specified element.
387	>	* More formally, returns {@code true} if and only if this queue contains
388	>	* at least one element {@code e} such that {@code o.equals(e)}.
389		*
390		* @param o object to be checked for containment in this queue
391	<	* @return <tt>true</tt> if this queue contains the specified element
391	>	* @return {@code true} if this queue contains the specified element
392		*/
393		public boolean contains(Object o) {
394	<	return indexOf(o) != -1;
394	>	return indexOf(o) != -1;
395		}
396
397		/**
398	<	* Returns an array containing all of the elements in this queue,
398	>	* Returns an array containing all of the elements in this queue.
399		* The elements are in no particular order.
400		*
401		* <p>The returned array will be "safe" in that no references to it are
402	<	* maintained by this list.  (In other words, this method must allocate
402	>	* maintained by this queue.  (In other words, this method must allocate
403		* a new array).  The caller is thus free to modify the returned array.
404		*
405	<	* @return an array containing all of the elements in this queue.
405	>	* <p>This method acts as bridge between array-based and collection-based
406	>	* APIs.
407	>	*
408	>	* @return an array containing all of the elements in this queue
409		*/
410		public Object[] toArray() {
411		return Arrays.copyOf(queue, size);
412		}
413
414		/**
415	<	* Returns an array containing all of the elements in this queue.
416	<	* The elements are in no particular order.  The runtime type of
417	<	* the returned array is that of the specified array.  If the queue
418	<	* fits in the specified array, it is returned therein.
419	<	* Otherwise, a new array is allocated with the runtime type of
420	<	* the specified array and the size of this queue.
415	>	* Returns an array containing all of the elements in this queue; the
416	>	* runtime type of the returned array is that of the specified array.
417	>	* The returned array elements are in no particular order.
418	>	* If the queue fits in the specified array, it is returned therein.
419	>	* Otherwise, a new array is allocated with the runtime type of the
420	>	* specified array and the size of this queue.
421		*
422		* <p>If the queue fits in the specified array with room to spare
423		* (i.e., the array has more elements than the queue), the element in
424		* the array immediately following the end of the collection is set to
425	<	* <tt>null</tt>.  (This is useful in determining the length of the
426	<	* queue <i>only</i> if the caller knows that the queue does not contain
427	<	* any null elements.)
425	>	* {@code null}.
426	>	*
427	>	* <p>Like the {@link #toArray()} method, this method acts as bridge between
428	>	* array-based and collection-based APIs.  Further, this method allows
429	>	* precise control over the runtime type of the output array, and may,
430	>	* under certain circumstances, be used to save allocation costs.
431	>	*
432	>	* <p>Suppose <tt>x</tt> is a queue known to contain only strings.
433	>	* The following code can be used to dump the queue into a newly
434	>	* allocated array of <tt>String</tt>:
435	>	*
436	>	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
437	>	*
438	>	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
439	>	* <tt>toArray()</tt>.
440		*
441		* @param a the array into which the elements of the queue are to
442		*          be stored, if it is big enough; otherwise, a new array of the
443		*          same runtime type is allocated for this purpose.
444	<	* @return an array containing the elements of the queue
444	>	* @return an array containing all of the elements in this queue
445		* @throws ArrayStoreException if the runtime type of the specified array
446		*         is not a supertype of the runtime type of every element in
447		*         this queue
#	Line 378 | Line 451 | public class PriorityQueue<E> extends Ab
451		if (a.length < size)
452		// Make a new array of a's runtime type, but my contents:
453		return (T[]) Arrays.copyOf(queue, size, a.getClass());
454	<	System.arraycopy(queue, 0, a, 0, size);
454	>	System.arraycopy(queue, 0, a, 0, size);
455		if (a.length > size)
456		a[size] = null;
457		return a;
#	Line 417 | Line 490 | public class PriorityQueue<E> extends Ab
490		* after we've completed the "normal" iteration.
491		*
492		* We expect that most iterations, even those involving removals,
493	<	* will not use need to store elements in this field.
493	>	* will not need to store elements in this field.
494		*/
495		private ArrayDeque<E> forgetMeNot = null;
496
#	Line 429 | Line 502 | public class PriorityQueue<E> extends Ab
502
503		/**
504		* The modCount value that the iterator believes that the backing
505	<	* List should have.  If this expectation is violated, the iterator
505	>	* Queue should have.  If this expectation is violated, the iterator
506		* has detected concurrent modification.
507		*/
508		private int expectedModCount = modCount;
#	Line 456 | Line 529 | public class PriorityQueue<E> extends Ab
529		public void remove() {
530		if (expectedModCount != modCount)
531		throw new ConcurrentModificationException();
459	–	if (lastRet == -1 && lastRetElt == null)
460	–	throw new IllegalStateException();
532		if (lastRet != -1) {
533		E moved = PriorityQueue.this.removeAt(lastRet);
534		lastRet = -1;
#	Line 468 | Line 539 | public class PriorityQueue<E> extends Ab
539		forgetMeNot = new ArrayDeque<E>();
540		forgetMeNot.add(moved);
541		}
542	<	} else {
542	>	} else if (lastRetElt != null) {
543		PriorityQueue.this.removeEq(lastRetElt);
544		lastRetElt = null;
545	+	} else {
546	+	throw new IllegalStateException();
547		}
548		expectedModCount = modCount;
549		}
477	–
550		}
551
552		public int size() {
#	Line 497 | Line 569 | public class PriorityQueue<E> extends Ab
569		return null;
570		int s = --size;
571		modCount++;
572	<	E result = (E)queue[0];
573	<	E x = (E)queue[s];
572	>	E result = (E) queue[0];
573	>	E x = (E) queue[s];
574		queue[s] = null;
575		if (s != 0)
576		siftDown(0, x);
#	Line 515 | Line 587 | public class PriorityQueue<E> extends Ab
587		* i.  Under these circumstances, this method returns the element
588		* that was previously at the end of the list and is now at some
589		* position before i. This fact is used by iterator.remove so as to
590	<	* avoid missing traverseing elements.
590	>	* avoid missing traversing elements.
591		*/
592		private E removeAt(int i) {
593	<	assert i >= 0 && i < size;
593	>	// assert i >= 0 && i < size;
594		modCount++;
595		int s = --size;
596		if (s == i) // removed last element
#	Line 560 | Line 632 | public class PriorityQueue<E> extends Ab
632		while (k > 0) {
633		int parent = (k - 1) >>> 1;
634		Object e = queue[parent];
635	<	if (key.compareTo((E)e) >= 0)
635	>	if (key.compareTo((E) e) >= 0)
636		break;
637		queue[k] = e;
638		k = parent;
#	Line 572 | Line 644 | public class PriorityQueue<E> extends Ab
644		while (k > 0) {
645		int parent = (k - 1) >>> 1;
646		Object e = queue[parent];
647	<	if (comparator.compare(x, (E)e) >= 0)
647	>	if (comparator.compare(x, (E) e) >= 0)
648		break;
649		queue[k] = e;
650		k = parent;
#	Line 603 | Line 675 | public class PriorityQueue<E> extends Ab
675		Object c = queue[child];
676		int right = child + 1;
677		if (right < size &&
678	<	((Comparable<? super E>)c).compareTo((E)queue[right]) > 0)
678	>	((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
679		c = queue[child = right];
680	<	if (key.compareTo((E)c) <= 0)
680	>	if (key.compareTo((E) c) <= 0)
681		break;
682		queue[k] = c;
683		k = child;
#	Line 620 | Line 692 | public class PriorityQueue<E> extends Ab
692		Object c = queue[child];
693		int right = child + 1;
694		if (right < size &&
695	<	comparator.compare((E)c, (E)queue[right]) > 0)
695	>	comparator.compare((E) c, (E) queue[right]) > 0)
696		c = queue[child = right];
697	<	if (comparator.compare(x, (E)c) <= 0)
697	>	if (comparator.compare(x, (E) c) <= 0)
698		break;
699		queue[k] = c;
700		k = child;
#	Line 636 | Line 708 | public class PriorityQueue<E> extends Ab
708		*/
709		private void heapify() {
710		for (int i = (size >>> 1) - 1; i >= 0; i--)
711	<	siftDown(i, (E)queue[i]);
711	>	siftDown(i, (E) queue[i]);
712		}
713
714		/**
715		* Returns the comparator used to order the elements in this
716	<	* queue, or <tt>null</tt> if this queue is sorted according to
716	>	* queue, or {@code null} if this queue is sorted according to
717		* the {@linkplain Comparable natural ordering} of its elements.
718		*
719		* @return the comparator used to order this queue, or
720	<	*         <tt>null</tt> if this queue is sorted according to the
721	<	*         natural ordering of its elements.
720	>	*         {@code null} if this queue is sorted according to the
721	>	*         natural ordering of its elements
722		*/
723		public Comparator<? super E> comparator() {
724		return comparator;
725		}
726
727		/**
728	<	* Save the state of the instance to a stream (that
657	<	* is, serialize it).
728	>	* Saves this queue to a stream (that is, serializes it).
729		*
730		* @serialData The length of the array backing the instance is
731	<	* emitted (int), followed by all of its elements (each an
732	<	* <tt>Object</tt>) in the proper order.
662	<	* @param s the stream
731	>	*             emitted (int), followed by all of its elements
732	>	*             (each an {@code Object}) in the proper order.
733		*/
734		private void writeObject(java.io.ObjectOutputStream s)
735	<	throws java.io.IOException{
735	>	throws java.io.IOException {
736		// Write out element count, and any hidden stuff
737		s.defaultWriteObject();
738
739	<	// Write out array length
740	<	// For compatibility with 1.5 version, must be at least 2.
671	<	s.writeInt(Math.max(2, queue.length));
739	>	// Write out array length, for compatibility with 1.5 version
740	>	s.writeInt(Math.max(2, size + 1));
741
742	<	// Write out all elements in the proper order.
743	<	for (int i=0; i<size; i++)
742	>	// Write out all elements in the "proper order".
743	>	for (int i = 0; i < size; i++)
744		s.writeObject(queue[i]);
745		}
746
747		/**
748	<	* Reconstitute the <tt>PriorityQueue</tt> instance from a stream
680	<	* (that is, deserialize it).
681	<	* @param s the stream
748	>	* Reconstitutes this queue from a stream (that is, deserializes it).
749		*/
750		private void readObject(java.io.ObjectInputStream s)
751		throws java.io.IOException, ClassNotFoundException {
752		// Read in size, and any hidden stuff
753		s.defaultReadObject();
754
755	<	// Read in array length and allocate array
756	<	int arrayLength = s.readInt();
757	<	queue = new Object[arrayLength];
758	<
692	<	// Read in all elements in the proper order.
693	<	for (int i=0; i<size; i++)
694	<	queue[i] = (E) s.readObject();
695	<	}
755	>	// Read in (and discard) array length
756	>	s.readInt();
757	>
758	>	queue = new Object[size];
759
760	+	// Read in all elements.
761	+	for (int i = 0; i < size; i++)
762	+	queue[i] = s.readObject();
763	+
764	+	// Elements are guaranteed to be in "proper order", but the
765	+	// spec has never explained what that might be.
766	+	heapify();
767	+	}
768		}

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