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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 1.62 by jsr166, Thu Feb 16 08:17:21 2006 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
8		package java.util;
9	–	import java.util.*; // for javadoc (till 6280605 is fixed)
9
10		/**
11		* An unbounded priority {@linkplain Queue queue} based on a priority
#	Line 56 | Line 55 | import java.util.*; // for javadoc (till
55		* <a href="{@docRoot}/../guide/collections/index.html">
56		* Java Collections Framework</a>.
57		* @since 1.5
58	<	* @version 1.8, 08/27/05
58	>	* @version %I%, %G%
59		* @author Josh Bloch
60		* @param <E> the type of elements held in this collection
61		*/
#	Line 68 | Line 67 | public class PriorityQueue<E> extends Ab
67		private static final int DEFAULT_INITIAL_CAPACITY = 11;
68
69		/**
70	<	* Priority queue represented as a balanced binary heap: the two children
71	<	* of queue[n] are queue[2*n] and queue[2*n + 1].  The priority queue is
72	<	* ordered by comparator, or by the elements' natural ordering, if
73	<	* comparator is null:  For each node n in the heap and each descendant d
74	<	* of n, n <= d.
75	<	*
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.
70	>	* Priority queue represented as a balanced binary heap: the two
71	>	* children of queue[n] are queue[2*n+1] and queue[2*(n+1)].  The
72	>	* priority queue is ordered by comparator, or by the elements'
73	>	* natural ordering, if comparator is null: For each node n in the
74	>	* heap and each descendant d of n, n <= d.  The element with the
75	>	* lowest value is in queue[0], assuming the queue is nonempty.
76		*/
77		private transient Object[] queue;
78
#	Line 134 | Line 128 | public class PriorityQueue<E> extends Ab
128		*/
129		public PriorityQueue(int initialCapacity,
130		Comparator<? super E> comparator) {
131	+	// Note: This restriction of at least one is not actually needed,
132	+	// but continues for 1.5 compatibility
133		if (initialCapacity < 1)
134		throw new IllegalArgumentException();
135	<	this.queue = new Object[initialCapacity + 1];
135	>	this.queue = new Object[initialCapacity];
136		this.comparator = comparator;
137		}
138
139		/**
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	–	/**
140		* Creates a <tt>PriorityQueue</tt> containing the elements in the
141	<	* 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
141	>	* specified collection.   If the specified collection is an
142		* instance of a {@link java.util.SortedSet} or is another
143		* <tt>PriorityQueue</tt>, the priority queue will be ordered
144		* according to the same ordering.  Otherwise, this priority queue
#	Line 202 | Line 153 | public class PriorityQueue<E> extends Ab
153		*         of its elements are null
154		*/
155		public PriorityQueue(Collection<? extends E> c) {
156	<	initializeArray(c);
157	<	if (c instanceof SortedSet) {
158	<	SortedSet<? extends E> s = (SortedSet<? extends E>)c;
159	<	comparator = (Comparator<? super E>)s.comparator();
160	<	fillFromSorted(s);
161	<	} else if (c instanceof PriorityQueue) {
162	<	PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c;
163	<	comparator = (Comparator<? super E>)s.comparator();
213	<	fillFromSorted(s);
214	<	} else {
156	>	initFromCollection(c);
157	>	if (c instanceof SortedSet)
158	>	comparator = (Comparator<? super E>)
159	>	((SortedSet<? extends E>)c).comparator();
160	>	else if (c instanceof PriorityQueue)
161	>	comparator = (Comparator<? super E>)
162	>	((PriorityQueue<? extends E>)c).comparator();
163	>	else {
164		comparator = null;
165	<	fillFromUnsorted(c);
165	>	heapify();
166		}
167		}
168
169		/**
170		* Creates a <tt>PriorityQueue</tt> containing the elements in the
171	<	* 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
171	>	* specified priority queue.  This priority queue will be
172		* ordered according to the same ordering as the given priority
173		* queue.
174		*
#	Line 234 | Line 181 | public class PriorityQueue<E> extends Ab
181		*         of its elements are null
182		*/
183		public PriorityQueue(PriorityQueue<? extends E> c) {
237	–	initializeArray(c);
184		comparator = (Comparator<? super E>)c.comparator();
185	<	fillFromSorted(c);
185	>	initFromCollection(c);
186		}
187
188		/**
189		* Creates a <tt>PriorityQueue</tt> containing the elements in the
190	<	* 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
190	>	* specified sorted set.  This priority queue will be ordered
191		* according to the same ordering as the given sorted set.
192		*
193		* @param  c the sorted set whose elements are to be placed
#	Line 255 | Line 199 | public class PriorityQueue<E> extends Ab
199		*         of its elements are null
200		*/
201		public PriorityQueue(SortedSet<? extends E> c) {
258	–	initializeArray(c);
202		comparator = (Comparator<? super E>)c.comparator();
203	<	fillFromSorted(c);
203	>	initFromCollection(c);
204		}
205
206		/**
207	<	* Resize array, if necessary, to be able to hold given index.
207	>	* Initialize queue array with elements from the given Collection.
208	>	* @param c the collection
209		*/
210	<	private void grow(int index) {
211	<	int newlen = queue.length;
212	<	if (index < newlen) // don't need to grow
213	<	return;
214	<	if (index == Integer.MAX_VALUE)
210	>	private void initFromCollection(Collection<? extends E> c) {
211	>	Object[] a = c.toArray();
212	>	// If c.toArray incorrectly doesn't return Object[], copy it.
213	>	if (a.getClass() != Object[].class)
214	>	a = Arrays.copyOf(a, a.length, Object[].class);
215	>	queue = a;
216	>	size = a.length;
217	>	}
218	>
219	>	/**
220	>	* Increases the capacity of the array.
221	>	*
222	>	* @param minCapacity the desired minimum capacity
223	>	*/
224	>	private void grow(int minCapacity) {
225	>	if (minCapacity < 0) // overflow
226		throw new OutOfMemoryError();
227	<	while (newlen <= index) {
228	<	if (newlen >= Integer.MAX_VALUE / 2)  // avoid overflow
229	<	newlen = Integer.MAX_VALUE;
230	<	else
231	<	newlen <<= 2;
232	<	}
233	<	queue = Arrays.copyOf(queue, newlen);
227	>	int oldCapacity = queue.length;
228	>	// Double size if small; else grow by 50%
229	>	int newCapacity = ((oldCapacity < 64)?
230	>	((oldCapacity + 1) * 2):
231	>	((oldCapacity / 2) * 3));
232	>	if (newCapacity < 0) // overflow
233	>	newCapacity = Integer.MAX_VALUE;
234	>	if (newCapacity < minCapacity)
235	>	newCapacity = minCapacity;
236	>	queue = Arrays.copyOf(queue, newCapacity);
237		}
238
239		/**
#	Line 304 | Line 262 | public class PriorityQueue<E> extends Ab
262		if (e == null)
263		throw new NullPointerException();
264		modCount++;
265	<	++size;
266	<
267	<	// Grow backing store if necessary
268	<	if (size >= queue.length)
269	<	grow(size);
270	<
271	<	queue[size] = e;
272	<	fixUp(size);
265	>	int i = size;
266	>	if (i >= queue.length)
267	>	grow(i + 1);
268	>	size = i + 1;
269	>	if (i == 0)
270	>	queue[0] = e;
271	>	else
272	>	siftUp(i, e);
273		return true;
274		}
275
276		public E peek() {
277		if (size == 0)
278		return null;
279	<	return (E) queue[1];
279	>	return (E) queue[0];
280		}
281
282		private int indexOf(Object o) {
283	<	if (o == null)
284	<	return -1;
285	<	for (int i = 1; i <= size; i++)
286	<	if (o.equals(queue[i]))
287	<	return i;
283	>	if (o != null) {
284	>	for (int i = 0; i < size; i++)
285	>	if (o.equals(queue[i]))
286	>	return i;
287	>	}
288		return -1;
289		}
290
#	Line 351 | Line 309 | public class PriorityQueue<E> extends Ab
309		}
310
311		/**
312	+	* Version of remove using reference equality, not equals.
313	+	* Needed by iterator.remove.
314	+	*
315	+	* @param o element to be removed from this queue, if present
316	+	* @return <tt>true</tt> if removed
317	+	*/
318	+	boolean removeEq(Object o) {
319	+	for (int i = 0; i < size; i++) {
320	+	if (o == queue[i]) {
321	+	removeAt(i);
322	+	return true;
323	+	}
324	+	}
325	+	return false;
326	+	}
327	+
328	+	/**
329		* Returns <tt>true</tt> if this queue contains the specified element.
330		* More formally, returns <tt>true</tt> if and only if this queue contains
331		* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
#	Line 370 | Line 345 | public class PriorityQueue<E> extends Ab
345		* maintained by this list.  (In other words, this method must allocate
346		* a new array).  The caller is thus free to modify the returned array.
347		*
348	<	* @return an array containing all of the elements in this queue.
348	>	* @return an array containing all of the elements in this queue
349		*/
350		public Object[] toArray() {
351	<	return Arrays.copyOfRange(queue, 1, size+1);
351	>	return Arrays.copyOf(queue, size);
352		}
353
354		/**
#	Line 403 | Line 378 | public class PriorityQueue<E> extends Ab
378		public <T> T[] toArray(T[] a) {
379		if (a.length < size)
380		// Make a new array of a's runtime type, but my contents:
381	<	return (T[]) Arrays.copyOfRange(queue, 1, size+1, a.getClass());
382	<	System.arraycopy(queue, 1, a, 0, size);
381	>	return (T[]) Arrays.copyOf(queue, size, a.getClass());
382	>	System.arraycopy(queue, 0, a, 0, size);
383		if (a.length > size)
384		a[size] = null;
385		return a;
#	Line 420 | Line 395 | public class PriorityQueue<E> extends Ab
395		return new Itr();
396		}
397
398	<	private class Itr implements Iterator<E> {
424	<
398	>	private final class Itr implements Iterator<E> {
399		/**
400		* Index (into queue array) of element to be returned by
401		* subsequent call to next.
402		*/
403	<	private int cursor = 1;
403	>	private int cursor = 0;
404
405		/**
406		* Index of element returned by most recent call to next,
407		* unless that element came from the forgetMeNot list.
408	<	* 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.
408	>	* Set to -1 if element is deleted by a call to remove.
409		*/
410	<	private int expectedModCount = modCount;
410	>	private int lastRet = -1;
411
412		/**
413	<	* A list of elements that were moved from the unvisited portion of
413	>	* A queue of elements that were moved from the unvisited portion of
414		* the heap into the visited portion as a result of "unlucky" element
415		* removals during the iteration.  (Unlucky element removals are those
416	<	* that require a fixup instead of a fixdown.)  We must visit all of
416	>	* that require a siftup instead of a siftdown.)  We must visit all of
417		* the elements in this list to complete the iteration.  We do this
418		* after we've completed the "normal" iteration.
419		*
420		* We expect that most iterations, even those involving removals,
421		* will not use need to store elements in this field.
422		*/
423	<	private ArrayList<E> forgetMeNot = null;
423	>	private ArrayDeque<E> forgetMeNot = null;
424
425		/**
426		* Element returned by the most recent call to next iff that
427		* element was drawn from the forgetMeNot list.
428		*/
429	<	private Object lastRetElt = null;
429	>	private E lastRetElt = null;
430	>
431	>	/**
432	>	* The modCount value that the iterator believes that the backing
433	>	* List should have.  If this expectation is violated, the iterator
434	>	* has detected concurrent modification.
435	>	*/
436	>	private int expectedModCount = modCount;
437
438		public boolean hasNext() {
439	<	return cursor <= size || forgetMeNot != null;
439	>	return cursor < size ||
440	>	(forgetMeNot != null && !forgetMeNot.isEmpty());
441		}
442
443		public E next() {
444	<	checkForComodification();
445	<	E result;
446	<	if (cursor <= size) {
447	<	result = (E) queue[cursor];
448	<	lastRet = cursor++;
449	<	}
450	<	else if (forgetMeNot == null)
451	<	throw new NoSuchElementException();
452	<	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;
444	>	if (expectedModCount != modCount)
445	>	throw new ConcurrentModificationException();
446	>	if (cursor < size)
447	>	return (E) queue[lastRet = cursor++];
448	>	if (forgetMeNot != null) {
449	>	lastRet = -1;
450	>	lastRetElt = forgetMeNot.poll();
451	>	if (lastRetElt != null)
452	>	return lastRetElt;
453		}
454	<	return result;
454	>	throw new NoSuchElementException();
455		}
456
457		public void remove() {
458	<	checkForComodification();
459	<
460	<	if (lastRet != 0) {
458	>	if (expectedModCount != modCount)
459	>	throw new ConcurrentModificationException();
460	>	if (lastRet == -1 && lastRetElt == null)
461	>	throw new IllegalStateException();
462	>	if (lastRet != -1) {
463		E moved = PriorityQueue.this.removeAt(lastRet);
464	<	lastRet = 0;
465	<	if (moved == null) {
464	>	lastRet = -1;
465	>	if (moved == null)
466		cursor--;
467	<	} else {
467	>	else {
468		if (forgetMeNot == null)
469	<	forgetMeNot = new ArrayList<E>();
469	>	forgetMeNot = new ArrayDeque<E>();
470		forgetMeNot.add(moved);
471		}
501	–	} else if (lastRetElt != null) {
502	–	PriorityQueue.this.remove(lastRetElt);
503	–	lastRetElt = null;
472		} else {
473	<	throw new IllegalStateException();
473	>	PriorityQueue.this.removeEq(lastRetElt);
474	>	lastRetElt = null;
475		}
507	–
476		expectedModCount = modCount;
477		}
478
511	–	final void checkForComodification() {
512	–	if (modCount != expectedModCount)
513	–	throw new ConcurrentModificationException();
514	–	}
479		}
480
481		public int size() {
#	Line 524 | Line 488 | public class PriorityQueue<E> extends Ab
488		*/
489		public void clear() {
490		modCount++;
491	<
528	<	// Null out element references to prevent memory leak
529	<	for (int i=1; i<=size; i++)
491	>	for (int i = 0; i < size; i++)
492		queue[i] = null;
531	–
493		size = 0;
494		}
495
496		public E poll() {
497		if (size == 0)
498		return null;
499	+	int s = --size;
500		modCount++;
501	<
502	<	E result = (E) queue[1];
503	<	queue[1] = queue[size];
504	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
505	<	if (size > 1)
544	<	fixDown(1);
545	<
501	>	E result = (E)queue[0];
502	>	E x = (E)queue[s];
503	>	queue[s] = null;
504	>	if (s != 0)
505	>	siftDown(0, x);
506		return result;
507		}
508
509		/**
510	<	* Removes and returns the ith element from queue.  (Recall that queue
551	<	* is one-based, so 1 <= i <= size.)
510	>	* Removes the ith element from queue.
511		*
512	<	* Normally this method leaves the elements at positions from 1 up to i-1,
513	<	* inclusive, untouched.  Under these circumstances, it returns null.
514	<	* Occasionally, in order to maintain the heap invariant, it must move
515	<	* the last element of the list to some index in the range [2, i-1],
516	<	* and move the element previously at position (i/2) to position i.
517	<	* Under these circumstances, this method returns the element that was
518	<	* previously at the end of the list and is now at some position between
519	<	* 2 and i-1 inclusive.
512	>	* Normally this method leaves the elements at up to i-1,
513	>	* inclusive, untouched.  Under these circumstances, it returns
514	>	* null.  Occasionally, in order to maintain the heap invariant,
515	>	* it must swap a later element of the list with one earlier than
516	>	* i.  Under these circumstances, this method returns the element
517	>	* that was previously at the end of the list and is now at some
518	>	* position before i. This fact is used by iterator.remove so as to
519	>	* avoid missing traverseing elements.
520		*/
521		private E removeAt(int i) {
522	<	assert i > 0 && i <= size;
522	>	assert i >= 0 && i < size;
523		modCount++;
524	<
525	<	E moved = (E) queue[size];
526	<	queue[i] = moved;
527	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
528	<	if (i <= size) {
529	<	fixDown(i);
524	>	int s = --size;
525	>	if (s == i) // removed last element
526	>	queue[i] = null;
527	>	else {
528	>	E moved = (E) queue[s];
529	>	queue[s] = null;
530	>	siftDown(i, moved);
531		if (queue[i] == moved) {
532	<	fixUp(i);
532	>	siftUp(i, moved);
533		if (queue[i] != moved)
534		return moved;
535		}
#	Line 578 | Line 538 | public class PriorityQueue<E> extends Ab
538		}
539
540		/**
541	<	* Establishes the heap invariant (described above) assuming the heap
542	<	* satisfies the invariant except possibly for the leaf-node indexed by k
543	<	* (which may have a nextExecutionTime less than its parent's).
544	<	*
545	<	* This method functions by "promoting" queue[k] up the hierarchy
546	<	* (by swapping it with its parent) repeatedly until queue[k]
547	<	* is greater than or equal to its parent.
548	<	*/
549	<	private void fixUp(int k) {
550	<	if (comparator == null) {
551	<	while (k > 1) {
552	<	int j = k >> 1;
553	<	if (((Comparable<? super E>)queue[j]).compareTo((E)queue[k]) <= 0)
554	<	break;
555	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
556	<	k = j;
557	<	}
558	<	} else {
559	<	while (k > 1) {
560	<	int j = k >>> 1;
561	<	if (comparator.compare((E)queue[j], (E)queue[k]) <= 0)
562	<	break;
563	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
564	<	k = j;
565	<	}
566	<	}
567	<	}
568	<
569	<	/**
570	<	* Establishes the heap invariant (described above) in the subtree
571	<	* rooted at k, which is assumed to satisfy the heap invariant except
572	<	* possibly for node k itself (which may be greater than its children).
573	<	*
574	<	* This method functions by "demoting" queue[k] down the hierarchy
575	<	* (by swapping it with its smaller child) repeatedly until queue[k]
576	<	* is less than or equal to its children.
577	<	*/
578	<	private void fixDown(int k) {
579	<	int j;
580	<	if (comparator == null) {
581	<	while ((j = k << 1) <= size && (j > 0)) {
582	<	if (j<size &&
583	<	((Comparable<? super E>)queue[j]).compareTo((E)queue[j+1]) > 0)
584	<	j++; // j indexes smallest kid
585	<
586	<	if (((Comparable<? super E>)queue[k]).compareTo((E)queue[j]) <= 0)
587	<	break;
588	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
589	<	k = j;
590	<	}
591	<	} else {
592	<	while ((j = k << 1) <= size && (j > 0)) {
593	<	if (j<size &&
594	<	comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
595	<	j++; // j indexes smallest kid
596	<	if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
597	<	break;
598	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
599	<	k = j;
600	<	}
541	>	* Inserts item x at position k, maintaining heap invariant by
542	>	* promoting x up the tree until it is greater than or equal to
543	>	* its parent, or is the root.
544	>	*
545	>	* To simplify and speed up coercions and comparisons. the
546	>	* Comparable and Comparator versions are separated into different
547	>	* methods that are otherwise identical. (Similarly for siftDown.)
548	>	*
549	>	* @param k the position to fill
550	>	* @param x the item to insert
551	>	*/
552	>	private void siftUp(int k, E x) {
553	>	if (comparator != null)
554	>	siftUpUsingComparator(k, x);
555	>	else
556	>	siftUpComparable(k, x);
557	>	}
558	>
559	>	private void siftUpComparable(int k, E x) {
560	>	Comparable<? super E> key = (Comparable<? super E>) x;
561	>	while (k > 0) {
562	>	int parent = (k - 1) >>> 1;
563	>	Object e = queue[parent];
564	>	if (key.compareTo((E)e) >= 0)
565	>	break;
566	>	queue[k] = e;
567	>	k = parent;
568	>	}
569	>	queue[k] = key;
570	>	}
571	>
572	>	private void siftUpUsingComparator(int k, E x) {
573	>	while (k > 0) {
574	>	int parent = (k - 1) >>> 1;
575	>	Object e = queue[parent];
576	>	if (comparator.compare(x, (E)e) >= 0)
577	>	break;
578	>	queue[k] = e;
579	>	k = parent;
580	>	}
581	>	queue[k] = x;
582	>	}
583	>
584	>	/**
585	>	* Inserts item x at position k, maintaining heap invariant by
586	>	* demoting x down the tree repeatedly until it is less than or
587	>	* equal to its children or is a leaf.
588	>	*
589	>	* @param k the position to fill
590	>	* @param x the item to insert
591	>	*/
592	>	private void siftDown(int k, E x) {
593	>	if (comparator != null)
594	>	siftDownUsingComparator(k, x);
595	>	else
596	>	siftDownComparable(k, x);
597	>	}
598	>
599	>	private void siftDownComparable(int k, E x) {
600	>	Comparable<? super E> key = (Comparable<? super E>)x;
601	>	int half = size >>> 1;        // loop while a non-leaf
602	>	while (k < half) {
603	>	int child = (k << 1) + 1; // assume left child is least
604	>	Object c = queue[child];
605	>	int right = child + 1;
606	>	if (right < size &&
607	>	((Comparable<? super E>)c).compareTo((E)queue[right]) > 0)
608	>	c = queue[child = right];
609	>	if (key.compareTo((E)c) <= 0)
610	>	break;
611	>	queue[k] = c;
612	>	k = child;
613	>	}
614	>	queue[k] = key;
615	>	}
616	>
617	>	private void siftDownUsingComparator(int k, E x) {
618	>	int half = size >>> 1;
619	>	while (k < half) {
620	>	int child = (k << 1) + 1;
621	>	Object c = queue[child];
622	>	int right = child + 1;
623	>	if (right < size &&
624	>	comparator.compare((E)c, (E)queue[right]) > 0)
625	>	c = queue[child = right];
626	>	if (comparator.compare(x, (E)c) <= 0)
627	>	break;
628	>	queue[k] = c;
629	>	k = child;
630		}
631	+	queue[k] = x;
632		}
633
634		/**
#	Line 646 | Line 636 | public class PriorityQueue<E> extends Ab
636		* assuming nothing about the order of the elements prior to the call.
637		*/
638		private void heapify() {
639	<	for (int i = size/2; i >= 1; i--)
640	<	fixDown(i);
639	>	for (int i = (size >>> 1) - 1; i >= 0; i--)
640	>	siftDown(i, (E)queue[i]);
641		}
642
643		/**
#	Line 678 | Line 668 | public class PriorityQueue<E> extends Ab
668		s.defaultWriteObject();
669
670		// Write out array length
671	<	s.writeInt(queue.length);
671	>	// For compatibility with 1.5 version, must be at least 2.
672	>	s.writeInt(Math.max(2, queue.length));
673
674		// Write out all elements in the proper order.
675	<	for (int i=1; i<=size; i++)
675	>	for (int i=0; i<size; i++)
676		s.writeObject(queue[i]);
677		}
678
#	Line 700 | Line 691 | public class PriorityQueue<E> extends Ab
691		queue = new Object[arrayLength];
692
693		// Read in all elements in the proper order.
694	<	for (int i=1; i<=size; i++)
694	>	for (int i=0; i<size; i++)
695		queue[i] = (E) s.readObject();
696		}
697

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