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root/jsr166/jsr166/src/main/java/util/PriorityQueue.java

Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.18 by dholmes, Mon Aug 4 01:48:39 2003 UTC vs.
Revision 1.36 by dl, Sat Aug 30 11:40:04 2003 UTC

#	Line 1 | Line 1
1		package java.util;
2
3		/**
4	<	* A priority queue based on a priority heap.  This queue orders
5	<	* elements according to an order specified at construction time, which is
6	<	* specified in the same manner as {@link java.util.TreeSet} and
7	<	* {@link java.util.TreeMap}: elements are ordered
8	<	* either according to their <i>natural order</i> (see {@link Comparable}), or
9	<	* according to a {@link java.util.Comparator}, depending on which
10	<	* constructor is used.
11	<	* <p>The <em>head</em> of this queue is the <em>least</em> element with
12	<	* respect to the specified ordering.
13	<	* If multiple elements are tied for least value, the
14	<	* head is one of those elements. A priority queue does not permit
4	>	* An unbounded priority {@linkplain Queue queue} based on a priority heap.
5	>	* This queue orders elements according to an order specified at construction
6	>	* time, which is specified in the same manner as {@link java.util.TreeSet}
7	>	* and {@link java.util.TreeMap}: elements are ordered either according to
8	>	* their <i>natural order</i> (see {@link Comparable}), or according to a
9	>	* {@link java.util.Comparator}, depending on which constructor is used.
10	>	* <p>The <em>head</em> of this queue is the <em>least</em> element with
11	>	* respect to the specified ordering.  If multiple elements are tied for least
12	>	* value, the head is one of those elements. A priority queue does not permit
13		* <tt>null</tt> elements.
14		*
15		* <p>The {@link #remove()} and {@link #poll()} methods remove and
#	Line 22 | Line 20
20		*
21		* <p>A priority queue has a <i>capacity</i>.  The capacity is the
22		* size of the array used internally to store the elements on the
23	<	* queue, and is limited to <tt>Integer.MAX_VALUE-1</tt>.
23	>	* queue.
24		* It is always at least as large as the queue size.  As
25		* elements are added to a priority queue, its capacity grows
26		* automatically.  The details of the growth policy are not specified.
27		*
28	+	* <p>The Iterator provided in method {@link #iterator()} is <em>not</em>
29	+	* guaranteed to traverse the elements of the PriorityQueue in any
30	+	* particular order. If you need ordered traversal, consider using
31	+	* <tt>Arrays.sort(pq.toArray())</tt>.
32	+	*
33	+	* <p> <strong>Note that this implementation is not synchronized.</strong>
34	+	* Multiple threads should not access a <tt>PriorityQueue</tt>
35	+	* instance concurrently if any of the threads modifies the list
36	+	* structurally. Instead, use the thread-safe {@link
37	+	* java.util.concurrent.PriorityBlockingQueue} class.
38	+	*
39	+	*
40		* <p>Implementation note: this implementation provides O(log(n)) time
41		* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>,
42		* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the
#	Line 41 | Line 51
51		* @author Josh Bloch
52		*/
53		public class PriorityQueue<E> extends AbstractQueue<E>
54	<	implements Sorted, Queue<E>, java.io.Serializable {
54	>	implements Queue<E>, java.io.Serializable {
55	>
56	>	private static final long serialVersionUID = -7720805057305804111L;
57
58		private static final int DEFAULT_INITIAL_CAPACITY = 11;
59
#	Line 78 | Line 90 | public class PriorityQueue<E> extends Ab
90		private transient int modCount = 0;
91
92		/**
93	<	* Create a <tt>PriorityQueue</tt> with the default initial capacity
93	>	* Creates a <tt>PriorityQueue</tt> with the default initial capacity
94		* (11) that orders its elements according to their natural
95	<	* ordering (using <tt>Comparable</tt>.)
95	>	* ordering (using <tt>Comparable</tt>).
96		*/
97		public PriorityQueue() {
98		this(DEFAULT_INITIAL_CAPACITY, null);
99		}
100
101		/**
102	<	* Create a <tt>PriorityQueue</tt> with the specified initial capacity
102	>	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
103		* that orders its elements according to their natural ordering
104	<	* (using <tt>Comparable</tt>.)
104	>	* (using <tt>Comparable</tt>).
105		*
106		* @param initialCapacity the initial capacity for this priority queue.
107	+	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
108	+	* than 1
109		*/
110		public PriorityQueue(int initialCapacity) {
111		this(initialCapacity, null);
112		}
113
114		/**
115	<	* Create a <tt>PriorityQueue</tt> with the specified initial capacity
115	>	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
116		* that orders its elements according to the specified comparator.
117		*
118		* @param initialCapacity the initial capacity for this priority queue.
#	Line 108 | Line 122 | public class PriorityQueue<E> extends Ab
122		* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
123		* than 1
124		*/
125	<	public PriorityQueue(int initialCapacity, Comparator<? super E> comparator) {
125	>	public PriorityQueue(int initialCapacity,
126	>	Comparator<? super E> comparator) {
127		if (initialCapacity < 1)
128		throw new IllegalArgumentException();
129		this.queue = new Object[initialCapacity + 1];
#	Line 116 | Line 131 | public class PriorityQueue<E> extends Ab
131		}
132
133		/**
134	<	* Create a <tt>PriorityQueue</tt> containing the elements in the specified
135	<	* collection.  The priority queue has an initial capacity of 110% of the
121	<	* size of the specified collection (bounded by
122	<	* <tt>Integer.MAX_VALUE-1</tt>); or 1 if the collection is empty.
123	<	* If the specified collection
124	<	* implements the {@link Sorted} interface, the priority queue will be
125	<	* sorted according to the same comparator, or according to its elements'
126	<	* natural order if the collection is sorted according to its elements'
127	<	* natural order.  If the specified collection does not implement
128	<	* <tt>Sorted</tt>, the priority queue is ordered according to
129	<	* its elements' natural order.
130	<	*
131	<	* @param c the collection whose elements are to be placed
132	<	*        into this priority queue.
133	<	* @throws ClassCastException if elements of the specified collection
134	<	*         cannot be compared to one another according to the priority
135	<	*         queue's ordering.
136	<	* @throws NullPointerException if <tt>c</tt> or any element within it
137	<	* is <tt>null</tt>
134	>	* Common code to initialize underlying queue array across
135	>	* constructors below.
136		*/
137	<	public PriorityQueue(Collection<? extends E> c) {
137	>	private void initializeArray(Collection<? extends E> c) {
138		int sz = c.size();
139		int initialCapacity = (int)Math.min((sz * 110L) / 100,
140		Integer.MAX_VALUE - 1);
#	Line 144 | Line 142 | public class PriorityQueue<E> extends Ab
142		initialCapacity = 1;
143
144		this.queue = new Object[initialCapacity + 1];
145	+	}
146
147	<	// FIXME: if c is larger than Integer.MAX_VALUE we'll
148	<	// overflow the array
147	>	/**
148	>	* Initially fill elements of the queue array under the
149	>	* knowledge that it is sorted or is another PQ, in which
150	>	* case we can just place the elements in the order presented.
151	>	*/
152	>	private void fillFromSorted(Collection<? extends E> c) {
153	>	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
154	>	queue[++size] = i.next();
155	>	}
156	>
157	>	/**
158	>	* Initially fill elements of the queue array that is not to our knowledge
159	>	* sorted, so we must rearrange the elements to guarantee the heap
160	>	* invariant.
161	>	*/
162	>	private void fillFromUnsorted(Collection<? extends E> c) {
163	>	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
164	>	queue[++size] = i.next();
165	>	heapify();
166	>	}
167
168	<	if (c instanceof Sorted) {
169	<	comparator = ((Sorted)c).comparator();
168	>	/**
169	>	* Creates a <tt>PriorityQueue</tt> containing the elements in the
170	>	* specified collection.  The priority queue has an initial
171	>	* capacity of 110% of the size of the specified collection or 1
172	>	* if the collection is empty.  If the specified collection is an
173	>	* instance of a {@link java.util.SortedSet} or is another
174	>	* <tt>PriorityQueue</tt>, the priority queue will be sorted
175	>	* according to the same comparator, or according to its elements'
176	>	* natural order if the collection is sorted according to its
177	>	* elements' natural order.  Otherwise, the priority queue is
178	>	* ordered according to its elements' natural order.
179	>	*
180	>	* @param c the collection whose elements are to be placed
181	>	*        into this priority queue.
182	>	* @throws ClassCastException if elements of the specified collection
183	>	*         cannot be compared to one another according to the priority
184	>	*         queue's ordering.
185	>	* @throws NullPointerException if <tt>c</tt> or any element within it
186	>	* is <tt>null</tt>
187	>	*/
188	>	public PriorityQueue(Collection<? extends E> c) {
189	>	initializeArray(c);
190	>	if (c instanceof SortedSet) {
191	>	// @fixme double-cast workaround for compiler
192	>	SortedSet<? extends E> s = (SortedSet<? extends E>) (SortedSet)c;
193	>	comparator = (Comparator<? super E>)s.comparator();
194	>	fillFromSorted(s);
195	>	} else if (c instanceof PriorityQueue) {
196	>	PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c;
197	>	comparator = (Comparator<? super E>)s.comparator();
198	>	fillFromSorted(s);
199		} else {
200		comparator = null;
201	+	fillFromUnsorted(c);
202		}
203	+	}
204
205	<	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
206	<	add(i.next());
205	>	/**
206	>	* Creates a <tt>PriorityQueue</tt> containing the elements in the
207	>	* specified collection.  The priority queue has an initial
208	>	* capacity of 110% of the size of the specified collection or 1
209	>	* if the collection is empty.  This priority queue will be sorted
210	>	* according to the same comparator as the given collection, or
211	>	* according to its elements' natural order if the collection is
212	>	* sorted according to its elements' natural order.
213	>	*
214	>	* @param c the collection whose elements are to be placed
215	>	*        into this priority queue.
216	>	* @throws ClassCastException if elements of the specified collection
217	>	*         cannot be compared to one another according to the priority
218	>	*         queue's ordering.
219	>	* @throws NullPointerException if <tt>c</tt> or any element within it
220	>	* is <tt>null</tt>
221	>	*/
222	>	public PriorityQueue(PriorityQueue<? extends E> c) {
223	>	initializeArray(c);
224	>	comparator = (Comparator<? super E>)c.comparator();
225	>	fillFromSorted(c);
226	>	}
227	>
228	>	/**
229	>	* Creates a <tt>PriorityQueue</tt> containing the elements in the
230	>	* specified collection.  The priority queue has an initial
231	>	* capacity of 110% of the size of the specified collection or 1
232	>	* if the collection is empty.  This priority queue will be sorted
233	>	* according to the same comparator as the given collection, or
234	>	* according to its elements' natural order if the collection is
235	>	* sorted according to its elements' natural order.
236	>	*
237	>	* @param c the collection whose elements are to be placed
238	>	*        into this priority queue.
239	>	* @throws ClassCastException if elements of the specified collection
240	>	*         cannot be compared to one another according to the priority
241	>	*         queue's ordering.
242	>	* @throws NullPointerException if <tt>c</tt> or any element within it
243	>	* is <tt>null</tt>
244	>	*/
245	>	public PriorityQueue(SortedSet<? extends E> c) {
246	>	initializeArray(c);
247	>	comparator = (Comparator<? super E>)c.comparator();
248	>	fillFromSorted(c);
249	>	}
250	>
251	>	/**
252	>	* Resize array, if necessary, to be able to hold given index
253	>	*/
254	>	private void grow(int index) {
255	>	int newlen = queue.length;
256	>	if (index < newlen) // don't need to grow
257	>	return;
258	>	if (index == Integer.MAX_VALUE)
259	>	throw new OutOfMemoryError();
260	>	while (newlen <= index) {
261	>	if (newlen >= Integer.MAX_VALUE / 2)  // avoid overflow
262	>	newlen = Integer.MAX_VALUE;
263	>	else
264	>	newlen <<= 2;
265	>	}
266	>	Object[] newQueue = new Object[newlen];
267	>	System.arraycopy(queue, 0, newQueue, 0, queue.length);
268	>	queue = newQueue;
269		}
270	+
271
272		// Queue Methods
273
#	Line 176 | Line 287 | public class PriorityQueue<E> extends Ab
287		++size;
288
289		// Grow backing store if necessary
290	<	// FIXME: watch for overflow
291	<	// FIXME: what if we're full?
181	<	while (size >= queue.length) {
182	<	Object[] newQueue = new Object[2 * queue.length];
183	<	System.arraycopy(queue, 0, newQueue, 0, queue.length);
184	<	queue = newQueue;
185	<	}
290	>	if (size >= queue.length)
291	>	grow(size);
292
293		queue[size] = o;
294		fixUp(size);
#	Line 192 | Line 298 | public class PriorityQueue<E> extends Ab
298		public E poll() {
299		if (size == 0)
300		return null;
301	<	return (E) remove(1);
301	>	return remove();
302		}
303
304		public E peek() {
305		return (E) queue[1];
306		}
307
308	<	// Collection Methods
203	<
204	<	// these first two override just to get the throws docs
308	>	// Collection Methods - the first two override to update docs
309
310		/**
311	<	* @throws NullPointerException if the specified element is <tt>null</tt>.
311	>	* Adds the specified element to this queue.
312	>	* @return <tt>true</tt> (as per the general contract of
313	>	* <tt>Collection.add</tt>).
314	>	*
315	>	* @throws NullPointerException {@inheritDoc}
316		* @throws ClassCastException if the specified element cannot be compared
317		* with elements currently in the priority queue according
318		* to the priority queue's ordering.
#	Line 213 | Line 321 | public class PriorityQueue<E> extends Ab
321		return super.add(o);
322		}
323
324	+
325		/**
326	+	* Adds all of the elements in the specified collection to this queue.
327	+	* The behavior of this operation is undefined if
328	+	* the specified collection is modified while the operation is in
329	+	* progress.  (This implies that the behavior of this call is undefined if
330	+	* the specified collection is this queue, and this queue is nonempty.)
331	+	* <p>
332	+	* This implementation iterates over the specified collection, and adds
333	+	* each object returned by the iterator to this collection, in turn.
334	+	* @throws NullPointerException {@inheritDoc}
335		* @throws ClassCastException if any element cannot be compared
336		* with elements currently in the priority queue according
337		* to the priority queue's ordering.
220	–	* @throws NullPointerException if <tt>c</tt> or any element in <tt>c</tt>
221	–	* is <tt>null</tt>
338		*/
339		public boolean addAll(Collection<? extends E> c) {
340		return super.addAll(c);
341		}
342
343	+
344	+	/**
345	+	* Removes a single instance of the specified element from this
346	+	* queue, if it is present.  More formally,
347	+	* removes an element <tt>e</tt> such that <tt>(o==null ? e==null :
348	+	* o.equals(e))</tt>, if the queue contains one or more such
349	+	* elements.  Returns <tt>true</tt> if the queue contained the
350	+	* specified element (or equivalently, if the queue changed as a
351	+	* result of the call).
352	+	*
353	+	* <p>This implementation iterates over the queue looking for the
354	+	* specified element.  If it finds the element, it removes the element
355	+	* from the queue using the iterator's remove method.<p>
356	+	*
357	+	*/
358		public boolean remove(Object o) {
359		if (o == null)
360		return false;
#	Line 231 | Line 362 | public class PriorityQueue<E> extends Ab
362		if (comparator == null) {
363		for (int i = 1; i <= size; i++) {
364		if (((Comparable<E>)queue[i]).compareTo((E)o) == 0) {
365	<	remove(i);
365	>	removeAt(i);
366		return true;
367		}
368		}
369		} else {
370		for (int i = 1; i <= size; i++) {
371		if (comparator.compare((E)queue[i], (E)o) == 0) {
372	<	remove(i);
372	>	removeAt(i);
373		return true;
374		}
375		}
#	Line 246 | Line 377 | public class PriorityQueue<E> extends Ab
377		return false;
378		}
379
380	+	/**
381	+	* Returns an iterator over the elements in this queue. The iterator
382	+	* does not return the elements in any particular order.
383	+	*
384	+	* @return an iterator over the elements in this queue.
385	+	*/
386		public Iterator<E> iterator() {
387		return new Itr();
388		}
389
390		private class Itr implements Iterator<E> {
391	+
392		/**
393		* Index (into queue array) of element to be returned by
394		* subsequent call to next.
#	Line 258 | Line 396 | public class PriorityQueue<E> extends Ab
396		private int cursor = 1;
397
398		/**
399	<	* Index of element returned by most recent call to next or
400	<	* previous.  Reset to 0 if this element is deleted by a call
401	<	* to remove.
399	>	* Index of element returned by most recent call to next,
400	>	* unless that element came from the forgetMeNot list.
401	>	* Reset to 0 if element is deleted by a call to remove.
402		*/
403		private int lastRet = 0;
404
#	Line 271 | Line 409 | public class PriorityQueue<E> extends Ab
409		*/
410		private int expectedModCount = modCount;
411
412	+	/**
413	+	* A list 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
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;
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;
430	+
431		public boolean hasNext() {
432	<	return cursor <= size;
432	>	return cursor <= size || forgetMeNot != null;
433		}
434
435		public E next() {
436		checkForComodification();
437	<	if (cursor > size)
437	>	E result;
438	>	if (cursor <= size) {
439	>	result = (E) queue[cursor];
440	>	lastRet = cursor++;
441	>	}
442	>	else if (forgetMeNot == null)
443		throw new NoSuchElementException();
444	<	E result = (E) queue[cursor];
445	<	lastRet = cursor++;
444	>	else {
445	>	int remaining = forgetMeNot.size();
446	>	result = forgetMeNot.remove(remaining - 1);
447	>	if (remaining == 1)
448	>	forgetMeNot = null;
449	>	lastRet = 0;
450	>	lastRetElt = result;
451	>	}
452		return result;
453		}
454
455		public void remove() {
288	–	if (lastRet == 0)
289	–	throw new IllegalStateException();
456		checkForComodification();
457
458	<	PriorityQueue.this.remove(lastRet);
459	<	if (lastRet < cursor)
460	<	cursor--;
461	<	lastRet = 0;
458	>	if (lastRet != 0) {
459	>	E moved = PriorityQueue.this.removeAt(lastRet);
460	>	lastRet = 0;
461	>	if (moved == null) {
462	>	cursor--;
463	>	} else {
464	>	if (forgetMeNot == null)
465	>	forgetMeNot = new ArrayList();
466	>	forgetMeNot.add(moved);
467	>	}
468	>	} else if (lastRetElt != null) {
469	>	PriorityQueue.this.remove(lastRetElt);
470	>	lastRetElt = null;
471	>	} else {
472	>	throw new IllegalStateException();
473	>	}
474	>
475		expectedModCount = modCount;
476		}
477
#	Line 302 | Line 481 | public class PriorityQueue<E> extends Ab
481		}
482		}
483
305	–	/**
306	–	* Returns the number of elements in this priority queue.
307	–	*
308	–	* @return the number of elements in this priority queue.
309	–	*/
484		public int size() {
485		return size;
486		}
#	Line 325 | Line 499 | public class PriorityQueue<E> extends Ab
499		}
500
501		/**
502	<	* Removes and returns the ith element from queue.  Recall
503	<	* that queue is one-based, so 1 <= i <= size.
502	>	* Removes and returns the first element from queue.
503	>	*/
504	>	public E remove() {
505	>	if (size == 0)
506	>	throw new NoSuchElementException();
507	>	modCount++;
508	>
509	>	E result = (E) queue[1];
510	>	queue[1] = queue[size];
511	>	queue[size--] = null;  // Drop extra ref to prevent memory leak
512	>	if (size > 1)
513	>	fixDown(1);
514	>
515	>	return result;
516	>	}
517	>
518	>	/**
519	>	* Removes and returns the ith element from queue.  (Recall that queue
520	>	* is one-based, so 1 <= i <= size.)
521		*
522	<	* XXX: Could further special-case i==size, but is it worth it?
523	<	* XXX: Could special-case i==0, but is it worth it?
522	>	* Normally this method leaves the elements at positions from 1 up to i-1,
523	>	* inclusive, untouched.  Under these circumstances, it returns null.
524	>	* Occasionally, in order to maintain the heap invariant, it must move
525	>	* the last element of the list to some index in the range [2, i-1],
526	>	* and move the element previously at position (i/2) to position i.
527	>	* Under these circumstances, this method returns the element that was
528	>	* previously at the end of the list and is now at some position between
529	>	* 2 and i-1 inclusive.
530		*/
531	<	private E remove(int i) {
532	<	assert i <= size;
531	>	private E removeAt(int i) {
532	>	assert i > 0 && i <= size;
533		modCount++;
534
535	<	E result = (E) queue[i];
536	<	queue[i] = queue[size];
535	>	E moved = (E) queue[size];
536	>	queue[i] = moved;
537		queue[size--] = null;  // Drop extra ref to prevent memory leak
538	<	if (i <= size)
538	>	if (i <= size) {
539		fixDown(i);
540	<	return result;
540	>	if (queue[i] == moved) {
541	>	fixUp(i);
542	>	if (queue[i] != moved)
543	>	return moved;
544	>	}
545	>	}
546	>	return null;
547		}
548
549		/**
#	Line 363 | Line 566 | public class PriorityQueue<E> extends Ab
566		}
567		} else {
568		while (k > 1) {
569	<	int j = k >> 1;
569	>	int j = k >>> 1;
570		if (comparator.compare((E)queue[j], (E)queue[k]) <= 0)
571		break;
572		Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
#	Line 384 | Line 587 | public class PriorityQueue<E> extends Ab
587		private void fixDown(int k) {
588		int j;
589		if (comparator == null) {
590	<	while ((j = k << 1) <= size) {
591	<	if (j<size && ((Comparable<E>)queue[j]).compareTo((E)queue[j+1]) > 0)
590	>	while ((j = k << 1) <= size && (j > 0)) {
591	>	if (j<size &&
592	>	((Comparable<E>)queue[j]).compareTo((E)queue[j+1]) > 0)
593		j++; // j indexes smallest kid
594	+
595		if (((Comparable<E>)queue[k]).compareTo((E)queue[j]) <= 0)
596		break;
597		Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
598		k = j;
599		}
600		} else {
601	<	while ((j = k << 1) <= size) {
602	<	if (j < size && comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
601	>	while ((j = k << 1) <= size && (j > 0)) {
602	>	if (j<size &&
603	>	comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
604		j++; // j indexes smallest kid
605		if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
606		break;
#	Line 404 | Line 610 | public class PriorityQueue<E> extends Ab
610		}
611		}
612
613	+	/**
614	+	* Establishes the heap invariant (described above) in the entire tree,
615	+	* assuming nothing about the order of the elements prior to the call.
616	+	*/
617	+	private void heapify() {
618	+	for (int i = size/2; i >= 1; i--)
619	+	fixDown(i);
620	+	}
621	+
622	+	/**
623	+	* Returns the comparator used to order this collection, or <tt>null</tt>
624	+	* if this collection is sorted according to its elements natural ordering
625	+	* (using <tt>Comparable</tt>).
626	+	*
627	+	* @return the comparator used to order this collection, or <tt>null</tt>
628	+	* if this collection is sorted according to its elements natural ordering.
629	+	*/
630		public Comparator<? super E> comparator() {
631		return comparator;
632		}
#	Line 417 | Line 640 | public class PriorityQueue<E> extends Ab
640		* <tt>Object</tt>) in the proper order.
641		* @param s the stream
642		*/
643	<	private synchronized void writeObject(java.io.ObjectOutputStream s)
643	>	private void writeObject(java.io.ObjectOutputStream s)
644		throws java.io.IOException{
645		// Write out element count, and any hidden stuff
646		s.defaultWriteObject();
#	Line 435 | Line 658 | public class PriorityQueue<E> extends Ab
658		* deserialize it).
659		* @param s the stream
660		*/
661	<	private synchronized void readObject(java.io.ObjectInputStream s)
661	>	private void readObject(java.io.ObjectInputStream s)
662		throws java.io.IOException, ClassNotFoundException {
663		// Read in size, and any hidden stuff
664		s.defaultReadObject();
#	Line 450 | Line 673 | public class PriorityQueue<E> extends Ab
673		}
674
675		}
453	–

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