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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.52 by dl, Tue Nov 22 11:44:47 2005 UTC vs.
Revision 1.60 by jsr166, Mon Dec 5 02:56:59 2005 UTC

#	Line 1 | Line 1
1		/*
2	<	* @(#)PriorityQueue.java       1.8 05/08/27
2	>	* %W% %E%
3		*
4	<	* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
4	>	* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
5		* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6		*/
7
#	Line 68 | Line 68 | public class PriorityQueue<E> extends Ab
68		private static final int DEFAULT_INITIAL_CAPACITY = 11;
69
70		/**
71	<	* Priority queue represented as a balanced binary heap: the two children
72	<	* of queue[n] are queue[2*n] and queue[2*n + 1].  The priority queue is
73	<	* ordered by comparator, or by the elements' natural ordering, if
74	<	* comparator is null:  For each node n in the heap and each descendant d
75	<	* of n, n <= d.
76	<	*
77	<	* The element with the lowest value is in queue[1], assuming the queue is
78	<	* nonempty.  (A one-based array is used in preference to the traditional
79	<	* zero-based array to simplify parent and child calculations.)
80	<	*
81	<	* queue.length must be >= 2, even if size == 0.
71	>	* Priority queue represented as a balanced binary heap: the two
72	>	* children of queue[n] are queue[2*n+1] and queue[2*(n+1)].  The
73	>	* priority queue is ordered by comparator, or by the elements'
74	>	* natural ordering, if comparator is null: For each node n in the
75	>	* heap and each descendant d of n, n <= d.  The element with the
76	>	* lowest value is in queue[0], assuming the queue is nonempty.
77		*/
78		private transient Object[] queue;
79
#	Line 134 | Line 129 | public class PriorityQueue<E> extends Ab
129		*/
130		public PriorityQueue(int initialCapacity,
131		Comparator<? super E> comparator) {
132	+	// Note: This restriction of at least one is not actually needed,
133	+	// but continues for 1.5 compatibility
134		if (initialCapacity < 1)
135		throw new IllegalArgumentException();
136	<	this.queue = new Object[initialCapacity + 1];
136	>	this.queue = new Object[initialCapacity];
137		this.comparator = comparator;
138		}
139
140		/**
144	–	* Common code to initialize underlying queue array across
145	–	* constructors below.
146	–	*/
147	–	private void initializeArray(Collection<? extends E> c) {
148	–	int sz = c.size();
149	–	int initialCapacity = (int)Math.min((sz * 110L) / 100,
150	–	Integer.MAX_VALUE - 1);
151	–	if (initialCapacity < 1)
152	–	initialCapacity = 1;
153	–
154	–	this.queue = new Object[initialCapacity + 1];
155	–	}
156	–
157	–	/**
158	–	* Initially fill elements of the queue array under the
159	–	* knowledge that it is sorted or is another PQ, in which
160	–	* case we can just place the elements in the order presented.
161	–	*/
162	–	private void fillFromSorted(Collection<? extends E> c) {
163	–	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) {
164	–	int k = ++size;
165	–	if (k >= queue.length)
166	–	grow(k);
167	–	queue[k] = i.next();
168	–	}
169	–	}
170	–
171	–	/**
172	–	* Initially fill elements of the queue array that is not to our knowledge
173	–	* sorted, so we must rearrange the elements to guarantee the heap
174	–	* invariant.
175	–	*/
176	–	private void fillFromUnsorted(Collection<? extends E> c) {
177	–	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) {
178	–	int k = ++size;
179	–	if (k >= queue.length)
180	–	grow(k);
181	–	queue[k] = i.next();
182	–	}
183	–	heapify();
184	–	}
185	–
186	–	/**
141		* Creates a <tt>PriorityQueue</tt> containing the elements in the
142	<	* specified collection.  The priority queue has an initial
189	<	* capacity of 110% of the size of the specified collection or 1
190	<	* if the collection is empty.  If the specified collection is an
142	>	* specified collection.   If the specified collection is an
143		* instance of a {@link java.util.SortedSet} or is another
144		* <tt>PriorityQueue</tt>, the priority queue will be ordered
145		* according to the same ordering.  Otherwise, this priority queue
#	Line 202 | Line 154 | public class PriorityQueue<E> extends Ab
154		*         of its elements are null
155		*/
156		public PriorityQueue(Collection<? extends E> c) {
157	<	initializeArray(c);
158	<	if (c instanceof SortedSet) {
159	<	SortedSet<? extends E> s = (SortedSet<? extends E>)c;
160	<	comparator = (Comparator<? super E>)s.comparator();
161	<	fillFromSorted(s);
162	<	} else if (c instanceof PriorityQueue) {
163	<	PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c;
164	<	comparator = (Comparator<? super E>)s.comparator();
213	<	fillFromSorted(s);
214	<	} else {
157	>	initFromCollection(c);
158	>	if (c instanceof SortedSet)
159	>	comparator = (Comparator<? super E>)
160	>	((SortedSet<? extends E>)c).comparator();
161	>	else if (c instanceof PriorityQueue)
162	>	comparator = (Comparator<? super E>)
163	>	((PriorityQueue<? extends E>)c).comparator();
164	>	else {
165		comparator = null;
166	<	fillFromUnsorted(c);
166	>	heapify();
167		}
168		}
169
170		/**
171		* Creates a <tt>PriorityQueue</tt> containing the elements in the
172	<	* specified priority queue.  The priority queue has an initial
223	<	* capacity of 110% of the size of the specified priority queue or
224	<	* 1 if the priority queue is empty.  This priority queue will be
172	>	* specified priority queue.  This priority queue will be
173		* ordered according to the same ordering as the given priority
174		* queue.
175		*
#	Line 234 | Line 182 | public class PriorityQueue<E> extends Ab
182		*         of its elements are null
183		*/
184		public PriorityQueue(PriorityQueue<? extends E> c) {
237	–	initializeArray(c);
185		comparator = (Comparator<? super E>)c.comparator();
186	<	fillFromSorted(c);
186	>	initFromCollection(c);
187		}
188
189		/**
190		* Creates a <tt>PriorityQueue</tt> containing the elements in the
191	<	* specified sorted set.  The priority queue has an initial
245	<	* capacity of 110% of the size of the specified sorted set or 1
246	<	* if the sorted set is empty.  This priority queue will be ordered
191	>	* specified sorted set.  This priority queue will be ordered
192		* according to the same ordering as the given sorted set.
193		*
194		* @param  c the sorted set whose elements are to be placed
#	Line 255 | Line 200 | public class PriorityQueue<E> extends Ab
200		*         of its elements are null
201		*/
202		public PriorityQueue(SortedSet<? extends E> c) {
258	–	initializeArray(c);
203		comparator = (Comparator<? super E>)c.comparator();
204	<	fillFromSorted(c);
204	>	initFromCollection(c);
205		}
206
207		/**
208	<	* Resize array, if necessary, to be able to hold given index.
208	>	* Initialize queue array with elements from the given Collection.
209	>	* @param c the collection
210		*/
211	<	private void grow(int index) {
212	<	int newlen = queue.length;
213	<	if (index < newlen) // don't need to grow
214	<	return;
215	<	if (index == Integer.MAX_VALUE)
211	>	private void initFromCollection(Collection<? extends E> c) {
212	>	Object[] a = c.toArray();
213	>	// If c.toArray incorrectly doesn't return Object[], copy it.
214	>	if (a.getClass() != Object[].class)
215	>	a = Arrays.copyOf(a, a.length, Object[].class);
216	>	queue = a;
217	>	size = a.length;
218	>	}
219	>
220	>	/**
221	>	* Increases the capacity of the array.
222	>	*
223	>	* @param minCapacity the desired minimum capacity
224	>	*/
225	>	private void grow(int minCapacity) {
226	>	if (minCapacity < 0) // overflow
227		throw new OutOfMemoryError();
228	<	while (newlen <= index) {
229	<	if (newlen >= Integer.MAX_VALUE / 2)  // avoid overflow
230	<	newlen = Integer.MAX_VALUE;
231	<	else
232	<	newlen <<= 2;
233	<	}
234	<	queue = Arrays.copyOf(queue, newlen);
228	>	int oldCapacity = queue.length;
229	>	// Double size if small; else grow by 50%
230	>	int newCapacity = ((oldCapacity < 64)?
231	>	((oldCapacity + 1) * 2):
232	>	((oldCapacity / 2) * 3));
233	>	if (newCapacity < 0) // overflow
234	>	newCapacity = Integer.MAX_VALUE;
235	>	if (newCapacity < minCapacity)
236	>	newCapacity = minCapacity;
237	>	queue = Arrays.copyOf(queue, newCapacity);
238		}
239
240		/**
#	Line 304 | Line 263 | public class PriorityQueue<E> extends Ab
263		if (e == null)
264		throw new NullPointerException();
265		modCount++;
266	<	++size;
267	<
268	<	// Grow backing store if necessary
269	<	if (size >= queue.length)
270	<	grow(size);
271	<
272	<	queue[size] = e;
273	<	fixUp(size);
266	>	int i = size;
267	>	if (i >= queue.length)
268	>	grow(i + 1);
269	>	size = i + 1;
270	>	if (i == 0)
271	>	queue[0] = e;
272	>	else
273	>	siftUp(i, e);
274		return true;
275		}
276
277		public E peek() {
278		if (size == 0)
279		return null;
280	<	return (E) queue[1];
280	>	return (E) queue[0];
281		}
282
283		private int indexOf(Object o) {
284	<	if (o == null)
285	<	return -1;
286	<	for (int i = 1; i <= size; i++)
287	<	if (o.equals(queue[i]))
288	<	return i;
284	>	if (o != null) {
285	>	for (int i = 0; i < size; i++)
286	>	if (o.equals(queue[i]))
287	>	return i;
288	>	}
289		return -1;
290		}
291
#	Line 351 | Line 310 | public class PriorityQueue<E> extends Ab
310		}
311
312		/**
313	+	* Version of remove using reference equality, not equals.
314	+	* Needed by iterator.remove.
315	+	*
316	+	* @param o element to be removed from this queue, if present
317	+	* @return <tt>true</tt> if removed
318	+	*/
319	+	boolean removeEq(Object o) {
320	+	for (int i = 0; i < size; i++) {
321	+	if (o == queue[i]) {
322	+	removeAt(i);
323	+	return true;
324	+	}
325	+	}
326	+	return false;
327	+	}
328	+
329	+	/**
330		* Returns <tt>true</tt> if this queue contains the specified element.
331		* More formally, returns <tt>true</tt> if and only if this queue contains
332		* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
#	Line 370 | Line 346 | public class PriorityQueue<E> extends Ab
346		* maintained by this list.  (In other words, this method must allocate
347		* a new array).  The caller is thus free to modify the returned array.
348		*
349	<	* @return an array containing all of the elements in this queue.
349	>	* @return an array containing all of the elements in this queue
350		*/
351		public Object[] toArray() {
352	<	return Arrays.copyOfRange(queue, 1, size+1);
352	>	return Arrays.copyOf(queue, size);
353		}
354
355		/**
#	Line 403 | Line 379 | public class PriorityQueue<E> extends Ab
379		public <T> T[] toArray(T[] a) {
380		if (a.length < size)
381		// Make a new array of a's runtime type, but my contents:
382	<	return (T[]) Arrays.copyOfRange(queue, 1, size+1, a.getClass());
383	<	System.arraycopy(queue, 1, a, 0, size);
382	>	return (T[]) Arrays.copyOf(queue, size, a.getClass());
383	>	System.arraycopy(queue, 0, a, 0, size);
384		if (a.length > size)
385		a[size] = null;
386		return a;
#	Line 420 | Line 396 | public class PriorityQueue<E> extends Ab
396		return new Itr();
397		}
398
399	<	private class Itr implements Iterator<E> {
424	<
399	>	private final class Itr implements Iterator<E> {
400		/**
401		* Index (into queue array) of element to be returned by
402		* subsequent call to next.
403		*/
404	<	private int cursor = 1;
404	>	private int cursor = 0;
405
406		/**
407		* Index of element returned by most recent call to next,
408		* unless that element came from the forgetMeNot list.
409	<	* Reset to 0 if element is deleted by a call to remove.
435	<	*/
436	<	private int lastRet = 0;
437	<
438	<	/**
439	<	* The modCount value that the iterator believes that the backing
440	<	* List should have.  If this expectation is violated, the iterator
441	<	* has detected concurrent modification.
409	>	* Set to -1 if element is deleted by a call to remove.
410		*/
411	<	private int expectedModCount = modCount;
411	>	private int lastRet = -1;
412
413		/**
414	<	* A list of elements that were moved from the unvisited portion of
414	>	* A queue of elements that were moved from the unvisited portion of
415		* the heap into the visited portion as a result of "unlucky" element
416		* removals during the iteration.  (Unlucky element removals are those
417	<	* that require a fixup instead of a fixdown.)  We must visit all of
417	>	* that require a siftup instead of a siftdown.)  We must visit all of
418		* the elements in this list to complete the iteration.  We do this
419		* after we've completed the "normal" iteration.
420		*
421		* We expect that most iterations, even those involving removals,
422		* will not use need to store elements in this field.
423		*/
424	<	private ArrayList<E> forgetMeNot = null;
424	>	private ArrayDeque<E> forgetMeNot = null;
425
426		/**
427		* Element returned by the most recent call to next iff that
428		* element was drawn from the forgetMeNot list.
429		*/
430	<	private Object lastRetElt = null;
430	>	private E lastRetElt = null;
431	>
432	>	/**
433	>	* The modCount value that the iterator believes that the backing
434	>	* List should have.  If this expectation is violated, the iterator
435	>	* has detected concurrent modification.
436	>	*/
437	>	private int expectedModCount = modCount;
438
439		public boolean hasNext() {
440	<	return cursor <= size || forgetMeNot != null;
440	>	return cursor < size ||
441	>	(forgetMeNot != null && !forgetMeNot.isEmpty());
442		}
443
444		public E next() {
445	<	checkForComodification();
446	<	E result;
447	<	if (cursor <= size) {
448	<	result = (E) queue[cursor];
449	<	lastRet = cursor++;
450	<	}
451	<	else if (forgetMeNot == null)
452	<	throw new NoSuchElementException();
453	<	else {
478	<	int remaining = forgetMeNot.size();
479	<	result = forgetMeNot.remove(remaining - 1);
480	<	if (remaining == 1)
481	<	forgetMeNot = null;
482	<	lastRet = 0;
483	<	lastRetElt = result;
445	>	if (expectedModCount != modCount)
446	>	throw new ConcurrentModificationException();
447	>	if (cursor < size)
448	>	return (E) queue[lastRet = cursor++];
449	>	if (forgetMeNot != null) {
450	>	lastRet = -1;
451	>	lastRetElt = forgetMeNot.poll();
452	>	if (lastRetElt != null)
453	>	return lastRetElt;
454		}
455	<	return result;
455	>	throw new NoSuchElementException();
456		}
457
458		public void remove() {
459	<	checkForComodification();
460	<
461	<	if (lastRet != 0) {
459	>	if (expectedModCount != modCount)
460	>	throw new ConcurrentModificationException();
461	>	if (lastRet == -1 && lastRetElt == null)
462	>	throw new IllegalStateException();
463	>	if (lastRet != -1) {
464		E moved = PriorityQueue.this.removeAt(lastRet);
465	<	lastRet = 0;
466	<	if (moved == null) {
465	>	lastRet = -1;
466	>	if (moved == null)
467		cursor--;
468	<	} else {
468	>	else {
469		if (forgetMeNot == null)
470	<	forgetMeNot = new ArrayList<E>();
470	>	forgetMeNot = new ArrayDeque<E>();
471		forgetMeNot.add(moved);
472		}
501	–	} else if (lastRetElt != null) {
502	–	PriorityQueue.this.remove(lastRetElt);
503	–	lastRetElt = null;
473		} else {
474	<	throw new IllegalStateException();
474	>	PriorityQueue.this.removeEq(lastRetElt);
475	>	lastRetElt = null;
476		}
507	–
477		expectedModCount = modCount;
478		}
479
511	–	final void checkForComodification() {
512	–	if (modCount != expectedModCount)
513	–	throw new ConcurrentModificationException();
514	–	}
480		}
481
482		public int size() {
#	Line 524 | Line 489 | public class PriorityQueue<E> extends Ab
489		*/
490		public void clear() {
491		modCount++;
492	<
528	<	// Null out element references to prevent memory leak
529	<	for (int i=1; i<=size; i++)
492	>	for (int i = 0; i < size; i++)
493		queue[i] = null;
531	–
494		size = 0;
495		}
496
497		public E poll() {
498		if (size == 0)
499		return null;
500	+	int s = --size;
501		modCount++;
502	<
503	<	E result = (E) queue[1];
504	<	queue[1] = queue[size];
505	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
506	<	if (size > 1)
544	<	fixDown(1);
545	<
502	>	E result = (E)queue[0];
503	>	E x = (E)queue[s];
504	>	queue[s] = null;
505	>	if (s != 0)
506	>	siftDown(0, x);
507		return result;
508		}
509
510		/**
511	<	* Removes and returns the ith element from queue.  (Recall that queue
551	<	* is one-based, so 1 <= i <= size.)
511	>	* Removes the ith element from queue.
512		*
513	<	* Normally this method leaves the elements at positions from 1 up to i-1,
514	<	* inclusive, untouched.  Under these circumstances, it returns null.
515	<	* Occasionally, in order to maintain the heap invariant, it must move
516	<	* the last element of the list to some index in the range [2, i-1],
517	<	* and move the element previously at position (i/2) to position i.
518	<	* Under these circumstances, this method returns the element that was
519	<	* previously at the end of the list and is now at some position between
520	<	* 2 and i-1 inclusive.
513	>	* Normally this method leaves the elements at up to i-1,
514	>	* inclusive, untouched.  Under these circumstances, it returns
515	>	* null.  Occasionally, in order to maintain the heap invariant,
516	>	* it must swap a later element of the list with one earlier than
517	>	* i.  Under these circumstances, this method returns the element
518	>	* that was previously at the end of the list and is now at some
519	>	* position before i. This fact is used by iterator.remove so as to
520	>	* avoid missing traverseing elements.
521		*/
522		private E removeAt(int i) {
523	<	assert i > 0 && i <= size;
523	>	assert i >= 0 && i < size;
524		modCount++;
525	<
526	<	E moved = (E) queue[size];
527	<	queue[i] = moved;
528	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
529	<	if (i <= size) {
530	<	fixDown(i);
525	>	int s = --size;
526	>	if (s == i) // removed last element
527	>	queue[i] = null;
528	>	else {
529	>	E moved = (E) queue[s];
530	>	queue[s] = null;
531	>	siftDown(i, moved);
532		if (queue[i] == moved) {
533	<	fixUp(i);
533	>	siftUp(i, moved);
534		if (queue[i] != moved)
535		return moved;
536		}
#	Line 578 | Line 539 | public class PriorityQueue<E> extends Ab
539		}
540
541		/**
542	<	* Establishes the heap invariant (described above) assuming the heap
543	<	* satisfies the invariant except possibly for the leaf-node indexed by k
544	<	* (which may have a nextExecutionTime less than its parent's).
545	<	*
546	<	* This method functions by "promoting" queue[k] up the hierarchy
547	<	* (by swapping it with its parent) repeatedly until queue[k]
548	<	* is greater than or equal to its parent.
549	<	*/
550	<	private void fixUp(int k) {
551	<	if (comparator == null) {
552	<	while (k > 1) {
553	<	int j = k >> 1;
554	<	if (((Comparable<? super E>)queue[j]).compareTo((E)queue[k]) <= 0)
555	<	break;
556	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
557	<	k = j;
558	<	}
559	<	} else {
560	<	while (k > 1) {
561	<	int j = k >>> 1;
562	<	if (comparator.compare((E)queue[j], (E)queue[k]) <= 0)
563	<	break;
564	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
565	<	k = j;
566	<	}
567	<	}
568	<	}
569	<
570	<	/**
571	<	* Establishes the heap invariant (described above) in the subtree
572	<	* rooted at k, which is assumed to satisfy the heap invariant except
573	<	* possibly for node k itself (which may be greater than its children).
574	<	*
575	<	* This method functions by "demoting" queue[k] down the hierarchy
576	<	* (by swapping it with its smaller child) repeatedly until queue[k]
577	<	* is less than or equal to its children.
578	<	*/
579	<	private void fixDown(int k) {
580	<	int j;
581	<	if (comparator == null) {
582	<	while ((j = k << 1) <= size && (j > 0)) {
583	<	if (j<size &&
584	<	((Comparable<? super E>)queue[j]).compareTo((E)queue[j+1]) > 0)
585	<	j++; // j indexes smallest kid
586	<
587	<	if (((Comparable<? super E>)queue[k]).compareTo((E)queue[j]) <= 0)
588	<	break;
589	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
590	<	k = j;
591	<	}
592	<	} else {
593	<	while ((j = k << 1) <= size && (j > 0)) {
594	<	if (j<size &&
595	<	comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
596	<	j++; // j indexes smallest kid
597	<	if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
598	<	break;
599	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
600	<	k = j;
601	<	}
542	>	* Inserts item x at position k, maintaining heap invariant by
543	>	* promoting x up the tree until it is greater than or equal to
544	>	* its parent, or is the root.
545	>	*
546	>	* To simplify and speed up coercions and comparisons. the
547	>	* Comparable and Comparator versions are separated into different
548	>	* methods that are otherwise identical. (Similarly for siftDown.)
549	>	*
550	>	* @param k the position to fill
551	>	* @param x the item to insert
552	>	*/
553	>	private void siftUp(int k, E x) {
554	>	if (comparator != null)
555	>	siftUpUsingComparator(k, x);
556	>	else
557	>	siftUpComparable(k, x);
558	>	}
559	>
560	>	private void siftUpComparable(int k, E x) {
561	>	Comparable<? super E> key = (Comparable<? super E>) x;
562	>	while (k > 0) {
563	>	int parent = (k - 1) >>> 1;
564	>	Object e = queue[parent];
565	>	if (key.compareTo((E)e) >= 0)
566	>	break;
567	>	queue[k] = e;
568	>	k = parent;
569	>	}
570	>	queue[k] = key;
571	>	}
572	>
573	>	private void siftUpUsingComparator(int k, E x) {
574	>	while (k > 0) {
575	>	int parent = (k - 1) >>> 1;
576	>	Object e = queue[parent];
577	>	if (comparator.compare(x, (E)e) >= 0)
578	>	break;
579	>	queue[k] = e;
580	>	k = parent;
581	>	}
582	>	queue[k] = x;
583	>	}
584	>
585	>	/**
586	>	* Inserts item x at position k, maintaining heap invariant by
587	>	* demoting x down the tree repeatedly until it is less than or
588	>	* equal to its children or is a leaf.
589	>	*
590	>	* @param k the position to fill
591	>	* @param x the item to insert
592	>	*/
593	>	private void siftDown(int k, E x) {
594	>	if (comparator != null)
595	>	siftDownUsingComparator(k, x);
596	>	else
597	>	siftDownComparable(k, x);
598	>	}
599	>
600	>	private void siftDownComparable(int k, E x) {
601	>	Comparable<? super E> key = (Comparable<? super E>)x;
602	>	int half = size >>> 1;        // loop while a non-leaf
603	>	while (k < half) {
604	>	int child = (k << 1) + 1; // assume left child is least
605	>	Object c = queue[child];
606	>	int right = child + 1;
607	>	if (right < size &&
608	>	((Comparable<? super E>)c).compareTo((E)queue[right]) > 0)
609	>	c = queue[child = right];
610	>	if (key.compareTo((E)c) <= 0)
611	>	break;
612	>	queue[k] = c;
613	>	k = child;
614	>	}
615	>	queue[k] = key;
616	>	}
617	>
618	>	private void siftDownUsingComparator(int k, E x) {
619	>	int half = size >>> 1;
620	>	while (k < half) {
621	>	int child = (k << 1) + 1;
622	>	Object c = queue[child];
623	>	int right = child + 1;
624	>	if (right < size &&
625	>	comparator.compare((E)c, (E)queue[right]) > 0)
626	>	c = queue[child = right];
627	>	if (comparator.compare(x, (E)c) <= 0)
628	>	break;
629	>	queue[k] = c;
630	>	k = child;
631		}
632	+	queue[k] = x;
633		}
634
635		/**
#	Line 646 | Line 637 | public class PriorityQueue<E> extends Ab
637		* assuming nothing about the order of the elements prior to the call.
638		*/
639		private void heapify() {
640	<	for (int i = size/2; i >= 1; i--)
641	<	fixDown(i);
640	>	for (int i = (size >>> 1) - 1; i >= 0; i--)
641	>	siftDown(i, (E)queue[i]);
642		}
643
644		/**
#	Line 678 | Line 669 | public class PriorityQueue<E> extends Ab
669		s.defaultWriteObject();
670
671		// Write out array length
672	<	s.writeInt(queue.length);
672	>	// For compatibility with 1.5 version, must be at least 2.
673	>	s.writeInt(Math.max(2, queue.length));
674
675		// Write out all elements in the proper order.
676	<	for (int i=1; i<=size; i++)
676	>	for (int i=0; i<size; i++)
677		s.writeObject(queue[i]);
678		}
679
#	Line 700 | Line 692 | public class PriorityQueue<E> extends Ab
692		queue = new Object[arrayLength];
693
694		// Read in all elements in the proper order.
695	<	for (int i=1; i<=size; i++)
695	>	for (int i=0; i<size; i++)
696		queue[i] = (E) s.readObject();
697		}
698

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