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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.41 by dl, Sat Sep 13 18:51:06 2003 UTC vs.
Revision 1.127 by jsr166, Sun May 6 23:09:28 2018 UTC

#	Line 1 | Line 1
1		/*
2	<	* %W% %E%
2	>	* Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
3	>	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4		*
5	<	* Copyright 2003 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.  Oracle designates this
8	>	* particular file as subject to the "Classpath" exception as provided
9	>	* by Oracle 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;
27
28	+	import java.util.function.Consumer;
29	+	import jdk.internal.misc.SharedSecrets;
30	+
31		/**
32	<	* An unbounded priority {@linkplain Queue queue} based on a priority
33	<	* heap.  This queue orders elements according to an order specified
34	<	* at construction time, which is specified either according to their
35	<	* <i>natural order</i> (see {@link Comparable}), or according to a
36	<	* {@link java.util.Comparator}, depending on which constructor is
37	<	* used. A priority queue does not permit <tt>null</tt> elements.
32	>	* An unbounded priority {@linkplain Queue queue} based on a priority heap.
33	>	* The elements of the priority queue are ordered according to their
34	>	* {@linkplain Comparable natural ordering}, or by a {@link Comparator}
35	>	* provided at queue construction time, depending on which constructor is
36	>	* used.  A priority queue does not permit {@code null} elements.
37	>	* A priority queue relying on natural ordering also does not permit
38	>	* insertion of non-comparable objects (doing so may result in
39	>	* {@code ClassCastException}).
40		*
41		* <p>The <em>head</em> of this queue is the <em>least</em> element
42		* with respect to the specified ordering.  If multiple elements are
43		* tied for least value, the head is one of those elements -- ties are
44	<	* broken arbitrarily.  The {@link #remove()} and {@link #poll()}
45	<	* methods remove and return the head of the queue, and the {@link
46	<	* #element()} and {@link #peek()} methods return, but do not delete,
24	<	* the head of the queue.
44	>	* broken arbitrarily.  The queue retrieval operations {@code poll},
45	>	* {@code remove}, {@code peek}, and {@code element} access the
46	>	* element at the head of the queue.
47		*
48		* <p>A priority queue is unbounded, but has an internal
49		* <i>capacity</i> governing the size of an array used to store the
#	Line 30 | Line 52 | package java.util;
52		* grows automatically.  The details of the growth policy are not
53		* specified.
54		*
55	<	* <p>This class implements all of the <em>optional</em> methods of
56	<	* the {@link Collection} and {@link Iterator} interfaces.  The
57	<	* Iterator provided in method {@link #iterator()} is <em>not</em>
58	<	* guaranteed to traverse the elements of the PriorityQueue in any
59	<	* particular order. If you need ordered traversal, consider using
60	<	* <tt>Arrays.sort(pq.toArray())</tt>.
61	<	*
62	<	* <p> <strong>Note that this implementation is not synchronized.</strong>
63	<	* Multiple threads should not access a <tt>PriorityQueue</tt>
64	<	* instance concurrently if any of the threads modifies the list
65	<	* structurally. Instead, use the thread-safe {@link
55	>	* <p>This class and its iterator implement all of the
56	>	* <em>optional</em> methods of the {@link Collection} and {@link
57	>	* Iterator} interfaces.  The Iterator provided in method {@link
58	>	* #iterator()} and the Spliterator provided in method {@link #spliterator()}
59	>	* are <em>not</em> guaranteed to traverse the elements of
60	>	* the priority queue in any particular order. If you need ordered
61	>	* traversal, consider using {@code Arrays.sort(pq.toArray())}.
62	>	*
63	>	* <p><strong>Note that this implementation is not synchronized.</strong>
64	>	* Multiple threads should not access a {@code PriorityQueue}
65	>	* instance concurrently if any of the threads modifies the queue.
66	>	* Instead, use the thread-safe {@link
67		* java.util.concurrent.PriorityBlockingQueue} class.
68		*
69	<	*
70	<	* <p>Implementation note: this implementation provides O(log(n)) time
71	<	* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>,
72	<	* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the
73	<	* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and
74	<	* constant time for the retrieval methods (<tt>peek</tt>,
52	<	* <tt>element</tt>, and <tt>size</tt>).
69	>	* <p>Implementation note: this implementation provides
70	>	* O(log(n)) time for the enqueuing and dequeuing methods
71	>	* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
72	>	* linear time for the {@code remove(Object)} and {@code contains(Object)}
73	>	* methods; and constant time for the retrieval methods
74	>	* ({@code peek}, {@code element}, and {@code size}).
75		*
76		* <p>This class is a member of the
77	<	* <a href="{@docRoot}/../guide/collections/index.html">
77	>	* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
78		* Java Collections Framework</a>.
79	+	*
80		* @since 1.5
81	<	* @version %I%, %G%
82	<	* @author Josh Bloch
81	>	* @author Josh Bloch, Doug Lea
82	>	* @param <E> the type of elements held in this queue
83		*/
84	+	@SuppressWarnings("unchecked")
85		public class PriorityQueue<E> extends AbstractQueue<E>
86	<	implements Queue<E>, java.io.Serializable {
86	>	implements java.io.Serializable {
87
88		private static final long serialVersionUID = -7720805057305804111L;
89
90		private static final int DEFAULT_INITIAL_CAPACITY = 11;
91
92		/**
93	<	* Priority queue represented as a balanced binary heap: the two children
94	<	* of queue[n] are queue[2*n] and queue[2*n + 1].  The priority queue is
95	<	* ordered by comparator, or by the elements' natural ordering, if
96	<	* comparator is null:  For each node n in the heap and each descendant d
97	<	* of n, n <= d.
98	<	*
75	<	* The element with the lowest value is in queue[1], assuming the queue is
76	<	* nonempty.  (A one-based array is used in preference to the traditional
77	<	* zero-based array to simplify parent and child calculations.)
78	<	*
79	<	* queue.length must be >= 2, even if size == 0.
93	>	* Priority queue represented as a balanced binary heap: the two
94	>	* children of queue[n] are queue[2*n+1] and queue[2*(n+1)].  The
95	>	* priority queue is ordered by comparator, or by the elements'
96	>	* natural ordering, if comparator is null: For each node n in the
97	>	* heap and each descendant d of n, n <= d.  The element with the
98	>	* lowest value is in queue[0], assuming the queue is nonempty.
99		*/
100	<	private transient Object[] queue;
100	>	transient Object[] queue; // non-private to simplify nested class access
101
102		/**
103		* The number of elements in the priority queue.
104		*/
105	<	private int size = 0;
105	>	int size;
106
107		/**
108		* The comparator, or null if priority queue uses elements'
#	Line 95 | Line 114 | public class PriorityQueue<E> extends Ab
114		* The number of times this priority queue has been
115		* <i>structurally modified</i>.  See AbstractList for gory details.
116		*/
117	<	private transient int modCount = 0;
117	>	transient int modCount;     // non-private to simplify nested class access
118
119		/**
120	<	* Creates a <tt>PriorityQueue</tt> with the default initial capacity
121	<	* (11) that orders its elements according to their natural
122	<	* ordering (using <tt>Comparable</tt>).
120	>	* Creates a {@code PriorityQueue} with the default initial
121	>	* capacity (11) that orders its elements according to their
122	>	* {@linkplain Comparable natural ordering}.
123		*/
124		public PriorityQueue() {
125		this(DEFAULT_INITIAL_CAPACITY, null);
126		}
127
128		/**
129	<	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
130	<	* that orders its elements according to their natural ordering
131	<	* (using <tt>Comparable</tt>).
132	<	*
133	<	* @param initialCapacity the initial capacity for this priority queue.
134	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
135	<	* than 1
129	>	* Creates a {@code PriorityQueue} with the specified initial
130	>	* capacity that orders its elements according to their
131	>	* {@linkplain Comparable natural ordering}.
132	>	*
133	>	* @param initialCapacity the initial capacity for this priority queue
134	>	* @throws IllegalArgumentException if {@code initialCapacity} is less
135	>	*         than 1
136		*/
137		public PriorityQueue(int initialCapacity) {
138		this(initialCapacity, null);
139		}
140
141		/**
142	<	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
142	>	* Creates a {@code PriorityQueue} with the default initial capacity and
143	>	* whose elements are ordered according to the specified comparator.
144	>	*
145	>	* @param  comparator the comparator that will be used to order this
146	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
147	>	*         natural ordering} of the elements will be used.
148	>	* @since 1.8
149	>	*/
150	>	public PriorityQueue(Comparator<? super E> comparator) {
151	>	this(DEFAULT_INITIAL_CAPACITY, comparator);
152	>	}
153	>
154	>	/**
155	>	* Creates a {@code PriorityQueue} with the specified initial capacity
156		* that orders its elements according to the specified comparator.
157		*
158	<	* @param initialCapacity the initial capacity for this priority queue.
159	<	* @param comparator the comparator used to order this priority queue.
160	<	* If <tt>null</tt> then the order depends on the elements' natural
161	<	* ordering.
162	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
163	<	* than 1
158	>	* @param  initialCapacity the initial capacity for this priority queue
159	>	* @param  comparator the comparator that will be used to order this
160	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
161	>	*         natural ordering} of the elements will be used.
162	>	* @throws IllegalArgumentException if {@code initialCapacity} is
163	>	*         less than 1
164		*/
165	<	public PriorityQueue(int initialCapacity,
165	>	public PriorityQueue(int initialCapacity,
166		Comparator<? super E> comparator) {
167	+	// Note: This restriction of at least one is not actually needed,
168	+	// but continues for 1.5 compatibility
169		if (initialCapacity < 1)
170		throw new IllegalArgumentException();
171	<	this.queue = new Object[initialCapacity + 1];
171	>	this.queue = new Object[initialCapacity];
172		this.comparator = comparator;
173		}
174
175		/**
176	<	* Common code to initialize underlying queue array across
177	<	* constructors below.
176	>	* Creates a {@code PriorityQueue} containing the elements in the
177	>	* specified collection.  If the specified collection is an instance of
178	>	* a {@link SortedSet} or is another {@code PriorityQueue}, this
179	>	* priority queue will be ordered according to the same ordering.
180	>	* Otherwise, this priority queue will be ordered according to the
181	>	* {@linkplain Comparable natural ordering} of its elements.
182	>	*
183	>	* @param  c the collection whose elements are to be placed
184	>	*         into this priority queue
185	>	* @throws ClassCastException if elements of the specified collection
186	>	*         cannot be compared to one another according to the priority
187	>	*         queue's ordering
188	>	* @throws NullPointerException if the specified collection or any
189	>	*         of its elements are null
190		*/
191	<	private void initializeArray(Collection<? extends E> c) {
192	<	int sz = c.size();
193	<	int initialCapacity = (int)Math.min((sz * 110L) / 100,
194	<	Integer.MAX_VALUE - 1);
195	<	if (initialCapacity < 1)
196	<	initialCapacity = 1;
197	<
198	<	this.queue = new Object[initialCapacity + 1];
191	>	public PriorityQueue(Collection<? extends E> c) {
192	>	if (c instanceof SortedSet<?>) {
193	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
194	>	this.comparator = (Comparator<? super E>) ss.comparator();
195	>	initElementsFromCollection(ss);
196	>	}
197	>	else if (c instanceof PriorityQueue<?>) {
198	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
199	>	this.comparator = (Comparator<? super E>) pq.comparator();
200	>	initFromPriorityQueue(pq);
201	>	}
202	>	else {
203	>	this.comparator = null;
204	>	initFromCollection(c);
205	>	}
206		}
207
208		/**
209	<	* Initially fill elements of the queue array under the
210	<	* knowledge that it is sorted or is another PQ, in which
211	<	* case we can just place the elements in the order presented.
209	>	* Creates a {@code PriorityQueue} containing the elements in the
210	>	* specified priority queue.  This priority queue will be
211	>	* ordered according to the same ordering as the given priority
212	>	* queue.
213	>	*
214	>	* @param  c the priority queue whose elements are to be placed
215	>	*         into this priority queue
216	>	* @throws ClassCastException if elements of {@code c} cannot be
217	>	*         compared to one another according to {@code c}'s
218	>	*         ordering
219	>	* @throws NullPointerException if the specified priority queue or any
220	>	*         of its elements are null
221		*/
222	<	private void fillFromSorted(Collection<? extends E> c) {
223	<	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
224	<	queue[++size] = i.next();
222	>	public PriorityQueue(PriorityQueue<? extends E> c) {
223	>	this.comparator = (Comparator<? super E>) c.comparator();
224	>	initFromPriorityQueue(c);
225		}
226
227		/**
228	<	* Initially fill elements of the queue array that is not to our knowledge
229	<	* sorted, so we must rearrange the elements to guarantee the heap
230	<	* invariant.
228	>	* Creates a {@code PriorityQueue} containing the elements in the
229	>	* specified sorted set.   This priority queue will be ordered
230	>	* according to the same ordering as the given sorted set.
231	>	*
232	>	* @param  c the sorted set whose elements are to be placed
233	>	*         into this priority queue
234	>	* @throws ClassCastException if elements of the specified sorted
235	>	*         set cannot be compared to one another according to the
236	>	*         sorted set's ordering
237	>	* @throws NullPointerException if the specified sorted set or any
238	>	*         of its elements are null
239		*/
240	<	private void fillFromUnsorted(Collection<? extends E> c) {
241	<	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
242	<	queue[++size] = i.next();
173	<	heapify();
240	>	public PriorityQueue(SortedSet<? extends E> c) {
241	>	this.comparator = (Comparator<? super E>) c.comparator();
242	>	initElementsFromCollection(c);
243		}
244
245	<	/**
246	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
247	<	* specified collection.  The priority queue has an initial
248	<	* capacity of 110% of the size of the specified collection or 1
249	<	* if the collection is empty.  If the specified collection is an
250	<	* instance of a {@link java.util.SortedSet} or is another
251	<	* <tt>PriorityQueue</tt>, the priority queue will be sorted
252	<	* according to the same comparator, or according to its elements'
253	<	* natural order if the collection is sorted according to its
185	<	* elements' natural order.  Otherwise, the priority queue is
186	<	* ordered according to its elements' natural order.
187	<	*
188	<	* @param c the collection whose elements are to be placed
189	<	*        into this priority queue.
190	<	* @throws ClassCastException if elements of the specified collection
191	<	*         cannot be compared to one another according to the priority
192	<	*         queue's ordering.
193	<	* @throws NullPointerException if <tt>c</tt> or any element within it
194	<	* is <tt>null</tt>
195	<	*/
196	<	public PriorityQueue(Collection<? extends E> c) {
197	<	initializeArray(c);
198	<	if (c instanceof SortedSet) {
199	<	// @fixme double-cast workaround for compiler
200	<	SortedSet<? extends E> s = (SortedSet<? extends E>) (SortedSet)c;
201	<	comparator = (Comparator<? super E>)s.comparator();
202	<	fillFromSorted(s);
203	<	} else if (c instanceof PriorityQueue) {
204	<	PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c;
205	<	comparator = (Comparator<? super E>)s.comparator();
206	<	fillFromSorted(s);
245	>	/** Ensures that queue[0] exists, helping peek() and poll(). */
246	>	private static Object[] ensureNonEmpty(Object[] es) {
247	>	return (es.length > 0) ? es : new Object[1];
248	>	}
249	>
250	>	private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
251	>	if (c.getClass() == PriorityQueue.class) {
252	>	this.queue = ensureNonEmpty(c.toArray());
253	>	this.size = c.size();
254		} else {
255	<	comparator = null;
209	<	fillFromUnsorted(c);
255	>	initFromCollection(c);
256		}
257		}
258
259	+	private void initElementsFromCollection(Collection<? extends E> c) {
260	+	Object[] es = c.toArray();
261	+	int len = es.length;
262	+	// If c.toArray incorrectly doesn't return Object[], copy it.
263	+	if (es.getClass() != Object[].class)
264	+	es = Arrays.copyOf(es, len, Object[].class);
265	+	if (len == 1 || this.comparator != null)
266	+	for (Object e : es)
267	+	if (e == null)
268	+	throw new NullPointerException();
269	+	this.queue = ensureNonEmpty(es);
270	+	this.size = len;
271	+	}
272	+
273		/**
274	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
215	<	* specified collection.  The priority queue has an initial
216	<	* capacity of 110% of the size of the specified collection or 1
217	<	* if the collection is empty.  This priority queue will be sorted
218	<	* according to the same comparator as the given collection, or
219	<	* according to its elements' natural order if the collection is
220	<	* sorted according to its elements' natural order.
274	>	* Initializes queue array with elements from the given Collection.
275		*
276	<	* @param c the collection whose elements are to be placed
223	<	*        into this priority queue.
224	<	* @throws ClassCastException if elements of the specified collection
225	<	*         cannot be compared to one another according to the priority
226	<	*         queue's ordering.
227	<	* @throws NullPointerException if <tt>c</tt> or any element within it
228	<	* is <tt>null</tt>
276	>	* @param c the collection
277		*/
278	<	public PriorityQueue(PriorityQueue<? extends E> c) {
279	<	initializeArray(c);
280	<	comparator = (Comparator<? super E>)c.comparator();
233	<	fillFromSorted(c);
278	>	private void initFromCollection(Collection<? extends E> c) {
279	>	initElementsFromCollection(c);
280	>	heapify();
281		}
282
283		/**
284	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
285	<	* specified collection.  The priority queue has an initial
286	<	* capacity of 110% of the size of the specified collection or 1
287	<	* if the collection is empty.  This priority queue will be sorted
288	<	* according to the same comparator as the given collection, or
289	<	* according to its elements' natural order if the collection is
290	<	* sorted according to its elements' natural order.
284	>	* The maximum size of array to allocate.
285	>	* Some VMs reserve some header words in an array.
286	>	* Attempts to allocate larger arrays may result in
287	>	* OutOfMemoryError: Requested array size exceeds VM limit
288	>	*/
289	>	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
290	>
291	>	/**
292	>	* Increases the capacity of the array.
293		*
294	<	* @param c the collection whose elements are to be placed
246	<	*        into this priority queue.
247	<	* @throws ClassCastException if elements of the specified collection
248	<	*         cannot be compared to one another according to the priority
249	<	*         queue's ordering.
250	<	* @throws NullPointerException if <tt>c</tt> or any element within it
251	<	* is <tt>null</tt>
294	>	* @param minCapacity the desired minimum capacity
295		*/
296	<	public PriorityQueue(SortedSet<? extends E> c) {
297	<	initializeArray(c);
298	<	comparator = (Comparator<? super E>)c.comparator();
299	<	fillFromSorted(c);
296	>	private void grow(int minCapacity) {
297	>	int oldCapacity = queue.length;
298	>	// Double size if small; else grow by 50%
299	>	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
300	>	(oldCapacity + 2) :
301	>	(oldCapacity >> 1));
302	>	// overflow-conscious code
303	>	if (newCapacity - MAX_ARRAY_SIZE > 0)
304	>	newCapacity = hugeCapacity(minCapacity);
305	>	queue = Arrays.copyOf(queue, newCapacity);
306	>	}
307	>
308	>	private static int hugeCapacity(int minCapacity) {
309	>	if (minCapacity < 0) // overflow
310	>	throw new OutOfMemoryError();
311	>	return (minCapacity > MAX_ARRAY_SIZE) ?
312	>	Integer.MAX_VALUE :
313	>	MAX_ARRAY_SIZE;
314		}
315
316		/**
317	<	* Resize array, if necessary, to be able to hold given index
317	>	* Inserts the specified element into this priority queue.
318	>	*
319	>	* @return {@code true} (as specified by {@link Collection#add})
320	>	* @throws ClassCastException if the specified element cannot be
321	>	*         compared with elements currently in this priority queue
322	>	*         according to the priority queue's ordering
323	>	* @throws NullPointerException if the specified element is null
324		*/
325	<	private void grow(int index) {
326	<	int newlen = queue.length;
264	<	if (index < newlen) // don't need to grow
265	<	return;
266	<	if (index == Integer.MAX_VALUE)
267	<	throw new OutOfMemoryError();
268	<	while (newlen <= index) {
269	<	if (newlen >= Integer.MAX_VALUE / 2)  // avoid overflow
270	<	newlen = Integer.MAX_VALUE;
271	<	else
272	<	newlen <<= 2;
273	<	}
274	<	Object[] newQueue = new Object[newlen];
275	<	System.arraycopy(queue, 0, newQueue, 0, queue.length);
276	<	queue = newQueue;
325	>	public boolean add(E e) {
326	>	return offer(e);
327		}
278	–
328
329		/**
330	<	* Inserts the specified element to this priority queue.
330	>	* Inserts the specified element into this priority queue.
331		*
332	<	* @return <tt>true</tt>
333	<	* @throws ClassCastException if the specified element cannot be compared
334	<	* with elements currently in the priority queue according
335	<	* to the priority queue's ordering.
336	<	* @throws NullPointerException if the specified element is <tt>null</tt>.
332	>	* @return {@code true} (as specified by {@link Queue#offer})
333	>	* @throws ClassCastException if the specified element cannot be
334	>	*         compared with elements currently in this priority queue
335	>	*         according to the priority queue's ordering
336	>	* @throws NullPointerException if the specified element is null
337		*/
338	<	public boolean offer(E o) {
339	<	if (o == null)
338	>	public boolean offer(E e) {
339	>	if (e == null)
340		throw new NullPointerException();
341		modCount++;
342	<	++size;
343	<
344	<	// Grow backing store if necessary
345	<	if (size >= queue.length)
346	<	grow(size);
298	<
299	<	queue[size] = o;
300	<	fixUp(size);
342	>	int i = size;
343	>	if (i >= queue.length)
344	>	grow(i + 1);
345	>	siftUp(i, e);
346	>	size = i + 1;
347		return true;
348		}
349
350		public E peek() {
351	<	if (size == 0)
306	<	return null;
307	<	return (E) queue[1];
308	<	}
309	<
310	<	// Collection Methods - the first two override to update docs
311	<
312	<	/**
313	<	* Adds the specified element to this queue.
314	<	* @return <tt>true</tt> (as per the general contract of
315	<	* <tt>Collection.add</tt>).
316	<	*
317	<	* @throws NullPointerException if the specified element is <tt>null</tt>.
318	<	* @throws ClassCastException if the specified element cannot be compared
319	<	* with elements currently in the priority queue according
320	<	* to the priority queue's ordering.
321	<	*/
322	<	public boolean add(E o) {
323	<	return offer(o);
324	<	}
325	<
326	<
327	<	/**
328	<	* Adds all of the elements in the specified collection to this queue.
329	<	* The behavior of this operation is undefined if
330	<	* the specified collection is modified while the operation is in
331	<	* progress.  (This implies that the behavior of this call is undefined if
332	<	* the specified collection is this queue, and this queue is nonempty.)
333	<	* <p>
334	<	* This implementation iterates over the specified collection, and adds
335	<	* each object returned by the iterator to this collection, in turn.
336	<	* @param c collection whose elements are to be added to this queue
337	<	* @return <tt>true</tt> if this queue changed as a result of the
338	<	*         call.
339	<	* @throws NullPointerException if <tt>c</tt> or any element in <tt>c</tt>
340	<	* is <tt>null</tt>
341	<	* @throws ClassCastException if any element cannot be compared
342	<	* with elements currently in the priority queue according
343	<	* to the priority queue's ordering.
344	<	*/
345	<	public boolean addAll(Collection<? extends E> c) {
346	<	return super.addAll(c);
351	>	return (E) queue[0];
352		}
353
354	+	private int indexOf(Object o) {
355	+	if (o != null) {
356	+	final Object[] es = queue;
357	+	for (int i = 0, n = size; i < n; i++)
358	+	if (o.equals(es[i]))
359	+	return i;
360	+	}
361	+	return -1;
362	+	}
363	+
364	+	/**
365	+	* Removes a single instance of the specified element from this queue,
366	+	* if it is present.  More formally, removes an element {@code e} such
367	+	* that {@code o.equals(e)}, if this queue contains one or more such
368	+	* elements.  Returns {@code true} if and only if this queue contained
369	+	* the specified element (or equivalently, if this queue changed as a
370	+	* result of the call).
371	+	*
372	+	* @param o element to be removed from this queue, if present
373	+	* @return {@code true} if this queue changed as a result of the call
374	+	*/
375		public boolean remove(Object o) {
376	<	if (o == null)
376	>	int i = indexOf(o);
377	>	if (i == -1)
378		return false;
379	+	else {
380	+	removeAt(i);
381	+	return true;
382	+	}
383	+	}
384
385	<	if (comparator == null) {
386	<	for (int i = 1; i <= size; i++) {
387	<	if (((Comparable<E>)queue[i]).compareTo((E)o) == 0) {
388	<	removeAt(i);
389	<	return true;
390	<	}
391	<	}
392	<	} else {
393	<	for (int i = 1; i <= size; i++) {
394	<	if (comparator.compare((E)queue[i], (E)o) == 0) {
395	<	removeAt(i);
364	<	return true;
365	<	}
385	>	/**
386	>	* Identity-based version for use in Itr.remove.
387	>	*
388	>	* @param o element to be removed from this queue, if present
389	>	*/
390	>	void removeEq(Object o) {
391	>	final Object[] es = queue;
392	>	for (int i = 0, n = size; i < n; i++) {
393	>	if (o == es[i]) {
394	>	removeAt(i);
395	>	break;
396		}
397		}
398	<	return false;
398	>	}
399	>
400	>	/**
401	>	* Returns {@code true} if this queue contains the specified element.
402	>	* More formally, returns {@code true} if and only if this queue contains
403	>	* at least one element {@code e} such that {@code o.equals(e)}.
404	>	*
405	>	* @param o object to be checked for containment in this queue
406	>	* @return {@code true} if this queue contains the specified element
407	>	*/
408	>	public boolean contains(Object o) {
409	>	return indexOf(o) >= 0;
410	>	}
411	>
412	>	/**
413	>	* Returns an array containing all of the elements in this queue.
414	>	* The elements are in no particular order.
415	>	*
416	>	* <p>The returned array will be "safe" in that no references to it are
417	>	* maintained by this queue.  (In other words, this method must allocate
418	>	* a new array).  The caller is thus free to modify the returned array.
419	>	*
420	>	* <p>This method acts as bridge between array-based and collection-based
421	>	* APIs.
422	>	*
423	>	* @return an array containing all of the elements in this queue
424	>	*/
425	>	public Object[] toArray() {
426	>	return Arrays.copyOf(queue, size);
427	>	}
428	>
429	>	/**
430	>	* Returns an array containing all of the elements in this queue; the
431	>	* runtime type of the returned array is that of the specified array.
432	>	* The returned array elements are in no particular order.
433	>	* If the queue fits in the specified array, it is returned therein.
434	>	* Otherwise, a new array is allocated with the runtime type of the
435	>	* specified array and the size of this queue.
436	>	*
437	>	* <p>If the queue fits in the specified array with room to spare
438	>	* (i.e., the array has more elements than the queue), the element in
439	>	* the array immediately following the end of the collection is set to
440	>	* {@code null}.
441	>	*
442	>	* <p>Like the {@link #toArray()} method, this method acts as bridge between
443	>	* array-based and collection-based APIs.  Further, this method allows
444	>	* precise control over the runtime type of the output array, and may,
445	>	* under certain circumstances, be used to save allocation costs.
446	>	*
447	>	* <p>Suppose {@code x} is a queue known to contain only strings.
448	>	* The following code can be used to dump the queue into a newly
449	>	* allocated array of {@code String}:
450	>	*
451	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
452	>	*
453	>	* Note that {@code toArray(new Object[0])} is identical in function to
454	>	* {@code toArray()}.
455	>	*
456	>	* @param a the array into which the elements of the queue are to
457	>	*          be stored, if it is big enough; otherwise, a new array of the
458	>	*          same runtime type is allocated for this purpose.
459	>	* @return an array containing all of the elements in this queue
460	>	* @throws ArrayStoreException if the runtime type of the specified array
461	>	*         is not a supertype of the runtime type of every element in
462	>	*         this queue
463	>	* @throws NullPointerException if the specified array is null
464	>	*/
465	>	public <T> T[] toArray(T[] a) {
466	>	final int size = this.size;
467	>	if (a.length < size)
468	>	// Make a new array of a's runtime type, but my contents:
469	>	return (T[]) Arrays.copyOf(queue, size, a.getClass());
470	>	System.arraycopy(queue, 0, a, 0, size);
471	>	if (a.length > size)
472	>	a[size] = null;
473	>	return a;
474		}
475
476		/**
477		* Returns an iterator over the elements in this queue. The iterator
478		* does not return the elements in any particular order.
479		*
480	<	* @return an iterator over the elements in this queue.
480	>	* @return an iterator over the elements in this queue
481		*/
482		public Iterator<E> iterator() {
483		return new Itr();
484		}
485
486	<	private class Itr implements Iterator<E> {
382	<
486	>	private final class Itr implements Iterator<E> {
487		/**
488		* Index (into queue array) of element to be returned by
489		* subsequent call to next.
490		*/
491	<	private int cursor = 1;
491	>	private int cursor;
492
493		/**
494		* Index of element returned by most recent call to next,
495		* unless that element came from the forgetMeNot list.
496	<	* Reset to 0 if element is deleted by a call to remove.
496	>	* Set to -1 if element is deleted by a call to remove.
497		*/
498	<	private int lastRet = 0;
498	>	private int lastRet = -1;
499
500		/**
501	<	* The modCount value that the iterator believes that the backing
398	<	* List should have.  If this expectation is violated, the iterator
399	<	* has detected concurrent modification.
400	<	*/
401	<	private int expectedModCount = modCount;
402	<
403	<	/**
404	<	* A list of elements that were moved from the unvisited portion of
501	>	* A queue of elements that were moved from the unvisited portion of
502		* the heap into the visited portion as a result of "unlucky" element
503		* removals during the iteration.  (Unlucky element removals are those
504	<	* that require a fixup instead of a fixdown.)  We must visit all of
504	>	* that require a siftup instead of a siftdown.)  We must visit all of
505		* the elements in this list to complete the iteration.  We do this
506		* after we've completed the "normal" iteration.
507		*
508		* We expect that most iterations, even those involving removals,
509	<	* will not use need to store elements in this field.
509	>	* will not need to store elements in this field.
510		*/
511	<	private ArrayList<E> forgetMeNot = null;
511	>	private ArrayDeque<E> forgetMeNot;
512
513		/**
514		* Element returned by the most recent call to next iff that
515		* element was drawn from the forgetMeNot list.
516		*/
517	<	private Object lastRetElt = null;
517	>	private E lastRetElt;
518	>
519	>	/**
520	>	* The modCount value that the iterator believes that the backing
521	>	* Queue should have.  If this expectation is violated, the iterator
522	>	* has detected concurrent modification.
523	>	*/
524	>	private int expectedModCount = modCount;
525	>
526	>	Itr() {}                        // prevent access constructor creation
527
528		public boolean hasNext() {
529	<	return cursor <= size || forgetMeNot != null;
529	>	return cursor < size ||
530	>	(forgetMeNot != null && !forgetMeNot.isEmpty());
531		}
532
533		public E next() {
534	<	checkForComodification();
535	<	E result;
536	<	if (cursor <= size) {
537	<	result = (E) queue[cursor];
538	<	lastRet = cursor++;
539	<	}
540	<	else if (forgetMeNot == null)
541	<	throw new NoSuchElementException();
542	<	else {
436	<	int remaining = forgetMeNot.size();
437	<	result = forgetMeNot.remove(remaining - 1);
438	<	if (remaining == 1)
439	<	forgetMeNot = null;
440	<	lastRet = 0;
441	<	lastRetElt = result;
534	>	if (expectedModCount != modCount)
535	>	throw new ConcurrentModificationException();
536	>	if (cursor < size)
537	>	return (E) queue[lastRet = cursor++];
538	>	if (forgetMeNot != null) {
539	>	lastRet = -1;
540	>	lastRetElt = forgetMeNot.poll();
541	>	if (lastRetElt != null)
542	>	return lastRetElt;
543		}
544	<	return result;
544	>	throw new NoSuchElementException();
545		}
546
547		public void remove() {
548	<	checkForComodification();
549	<
550	<	if (lastRet != 0) {
548	>	if (expectedModCount != modCount)
549	>	throw new ConcurrentModificationException();
550	>	if (lastRet != -1) {
551		E moved = PriorityQueue.this.removeAt(lastRet);
552	<	lastRet = 0;
553	<	if (moved == null) {
552	>	lastRet = -1;
553	>	if (moved == null)
554		cursor--;
555	<	} else {
555	>	else {
556		if (forgetMeNot == null)
557	<	forgetMeNot = new ArrayList<E>();
557	>	forgetMeNot = new ArrayDeque<>();
558		forgetMeNot.add(moved);
559		}
560		} else if (lastRetElt != null) {
561	<	PriorityQueue.this.remove(lastRetElt);
561	>	PriorityQueue.this.removeEq(lastRetElt);
562		lastRetElt = null;
563		} else {
564		throw new IllegalStateException();
565		}
465	–
566		expectedModCount = modCount;
567		}
468	–
469	–	final void checkForComodification() {
470	–	if (modCount != expectedModCount)
471	–	throw new ConcurrentModificationException();
472	–	}
568		}
569
570		public int size() {
#	Line 477 | Line 572 | public class PriorityQueue<E> extends Ab
572		}
573
574		/**
575	<	* Remove all elements from the priority queue.
575	>	* Removes all of the elements from this priority queue.
576	>	* The queue will be empty after this call returns.
577		*/
578		public void clear() {
579		modCount++;
580	<
581	<	// Null out element references to prevent memory leak
582	<	for (int i=1; i<=size; i++)
487	<	queue[i] = null;
488	<
580	>	final Object[] es = queue;
581	>	for (int i = 0, n = size; i < n; i++)
582	>	es[i] = null;
583		size = 0;
584		}
585
586		public E poll() {
587	<	if (size == 0)
588	<	return null;
495	<	modCount++;
496	<
497	<	E result = (E) queue[1];
498	<	queue[1] = queue[size];
499	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
500	<	if (size > 1)
501	<	fixDown(1);
587	>	final Object[] es;
588	>	final E result;
589
590	+	if ((result = (E) ((es = queue)[0])) != null) {
591	+	modCount++;
592	+	final int n;
593	+	final E x = (E) es[(n = --size)];
594	+	es[n] = null;
595	+	if (n > 0) {
596	+	final Comparator<? super E> cmp;
597	+	if ((cmp = comparator) == null)
598	+	siftDownComparable(0, x, es, n);
599	+	else
600	+	siftDownUsingComparator(0, x, es, n, cmp);
601	+	}
602	+	}
603		return result;
604		}
605
606		/**
607	<	* Removes and returns the ith element from queue.  (Recall that queue
508	<	* is one-based, so 1 <= i <= size.)
607	>	* Removes the ith element from queue.
608		*
609	<	* Normally this method leaves the elements at positions from 1 up to i-1,
610	<	* inclusive, untouched.  Under these circumstances, it returns null.
611	<	* Occasionally, in order to maintain the heap invariant, it must move
612	<	* the last element of the list to some index in the range [2, i-1],
613	<	* and move the element previously at position (i/2) to position i.
614	<	* Under these circumstances, this method returns the element that was
615	<	* previously at the end of the list and is now at some position between
616	<	* 2 and i-1 inclusive.
617	<	*/
618	<	private E removeAt(int i) {
619	<	assert i > 0 && i <= size;
609	>	* Normally this method leaves the elements at up to i-1,
610	>	* inclusive, untouched.  Under these circumstances, it returns
611	>	* null.  Occasionally, in order to maintain the heap invariant,
612	>	* it must swap a later element of the list with one earlier than
613	>	* i.  Under these circumstances, this method returns the element
614	>	* that was previously at the end of the list and is now at some
615	>	* position before i. This fact is used by iterator.remove so as to
616	>	* avoid missing traversing elements.
617	>	*/
618	>	E removeAt(int i) {
619	>	// assert i >= 0 && i < size;
620	>	final Object[] es = queue;
621		modCount++;
622	<
623	<	E moved = (E) queue[size];
624	<	queue[i] = moved;
625	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
626	<	if (i <= size) {
627	<	fixDown(i);
628	<	if (queue[i] == moved) {
629	<	fixUp(i);
630	<	if (queue[i] != moved)
622	>	int s = --size;
623	>	if (s == i) // removed last element
624	>	es[i] = null;
625	>	else {
626	>	E moved = (E) es[s];
627	>	es[s] = null;
628	>	siftDown(i, moved);
629	>	if (es[i] == moved) {
630	>	siftUp(i, moved);
631	>	if (es[i] != moved)
632		return moved;
633		}
634		}
#	Line 535 | Line 636 | public class PriorityQueue<E> extends Ab
636		}
637
638		/**
639	<	* Establishes the heap invariant (described above) assuming the heap
640	<	* satisfies the invariant except possibly for the leaf-node indexed by k
641	<	* (which may have a nextExecutionTime less than its parent's).
642	<	*
643	<	* This method functions by "promoting" queue[k] up the hierarchy
644	<	* (by swapping it with its parent) repeatedly until queue[k]
645	<	* is greater than or equal to its parent.
646	<	*/
647	<	private void fixUp(int k) {
648	<	if (comparator == null) {
649	<	while (k > 1) {
650	<	int j = k >> 1;
651	<	if (((Comparable<E>)queue[j]).compareTo((E)queue[k]) <= 0)
652	<	break;
653	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
654	<	k = j;
655	<	}
656	<	} else {
657	<	while (k > 1) {
658	<	int j = k >>> 1;
659	<	if (comparator.compare((E)queue[j], (E)queue[k]) <= 0)
660	<	break;
661	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
662	<	k = j;
663	<	}
639	>	* Inserts item x at position k, maintaining heap invariant by
640	>	* promoting x up the tree until it is greater than or equal to
641	>	* its parent, or is the root.
642	>	*
643	>	* To simplify and speed up coercions and comparisons, the
644	>	* Comparable and Comparator versions are separated into different
645	>	* methods that are otherwise identical. (Similarly for siftDown.)
646	>	*
647	>	* @param k the position to fill
648	>	* @param x the item to insert
649	>	*/
650	>	private void siftUp(int k, E x) {
651	>	if (comparator != null)
652	>	siftUpUsingComparator(k, x, queue, comparator);
653	>	else
654	>	siftUpComparable(k, x, queue);
655	>	}
656	>
657	>	private static <T> void siftUpComparable(int k, T x, Object[] es) {
658	>	Comparable<? super T> key = (Comparable<? super T>) x;
659	>	while (k > 0) {
660	>	int parent = (k - 1) >>> 1;
661	>	Object e = es[parent];
662	>	if (key.compareTo((T) e) >= 0)
663	>	break;
664	>	es[k] = e;
665	>	k = parent;
666		}
667	+	es[k] = key;
668	+	}
669	+
670	+	private static <T> void siftUpUsingComparator(
671	+	int k, T x, Object[] es, Comparator<? super T> cmp) {
672	+	while (k > 0) {
673	+	int parent = (k - 1) >>> 1;
674	+	Object e = es[parent];
675	+	if (cmp.compare(x, (T) e) >= 0)
676	+	break;
677	+	es[k] = e;
678	+	k = parent;
679	+	}
680	+	es[k] = x;
681		}
682
683		/**
684	<	* Establishes the heap invariant (described above) in the subtree
685	<	* rooted at k, which is assumed to satisfy the heap invariant except
686	<	* possibly for node k itself (which may be greater than its children).
687	<	*
688	<	* This method functions by "demoting" queue[k] down the hierarchy
689	<	* (by swapping it with its smaller child) repeatedly until queue[k]
690	<	* is less than or equal to its children.
691	<	*/
692	<	private void fixDown(int k) {
693	<	int j;
694	<	if (comparator == null) {
695	<	while ((j = k << 1) <= size && (j > 0)) {
696	<	if (j<size &&
697	<	((Comparable<E>)queue[j]).compareTo((E)queue[j+1]) > 0)
698	<	j++; // j indexes smallest kid
699	<
700	<	if (((Comparable<E>)queue[k]).compareTo((E)queue[j]) <= 0)
701	<	break;
702	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
703	<	k = j;
704	<	}
705	<	} else {
706	<	while ((j = k << 1) <= size && (j > 0)) {
707	<	if (j<size &&
708	<	comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
709	<	j++; // j indexes smallest kid
710	<	if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
711	<	break;
712	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
596	<	k = j;
597	<	}
684	>	* Inserts item x at position k, maintaining heap invariant by
685	>	* demoting x down the tree repeatedly until it is less than or
686	>	* equal to its children or is a leaf.
687	>	*
688	>	* @param k the position to fill
689	>	* @param x the item to insert
690	>	*/
691	>	private void siftDown(int k, E x) {
692	>	if (comparator != null)
693	>	siftDownUsingComparator(k, x, queue, size, comparator);
694	>	else
695	>	siftDownComparable(k, x, queue, size);
696	>	}
697	>
698	>	private static <T> void siftDownComparable(int k, T x, Object[] es, int n) {
699	>	// assert n > 0;
700	>	Comparable<? super T> key = (Comparable<? super T>)x;
701	>	int half = n >>> 1;           // loop while a non-leaf
702	>	while (k < half) {
703	>	int child = (k << 1) + 1; // assume left child is least
704	>	Object c = es[child];
705	>	int right = child + 1;
706	>	if (right < n &&
707	>	((Comparable<? super T>) c).compareTo((T) es[right]) > 0)
708	>	c = es[child = right];
709	>	if (key.compareTo((T) c) <= 0)
710	>	break;
711	>	es[k] = c;
712	>	k = child;
713		}
714	+	es[k] = key;
715	+	}
716	+
717	+	private static <T> void siftDownUsingComparator(
718	+	int k, T x, Object[] es, int n, Comparator<? super T> cmp) {
719	+	// assert n > 0;
720	+	int half = n >>> 1;
721	+	while (k < half) {
722	+	int child = (k << 1) + 1;
723	+	Object c = es[child];
724	+	int right = child + 1;
725	+	if (right < n && cmp.compare((T) c, (T) es[right]) > 0)
726	+	c = es[child = right];
727	+	if (cmp.compare(x, (T) c) <= 0)
728	+	break;
729	+	es[k] = c;
730	+	k = child;
731	+	}
732	+	es[k] = x;
733		}
734
735		/**
736		* Establishes the heap invariant (described above) in the entire tree,
737		* assuming nothing about the order of the elements prior to the call.
738	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
739		*/
740		private void heapify() {
741	<	for (int i = size/2; i >= 1; i--)
742	<	fixDown(i);
741	>	final Object[] es = queue;
742	>	int n = size, i = (n >>> 1) - 1;
743	>	final Comparator<? super E> cmp;
744	>	if ((cmp = comparator) == null)
745	>	for (; i >= 0; i--)
746	>	siftDownComparable(i, (E) es[i], es, n);
747	>	else
748	>	for (; i >= 0; i--)
749	>	siftDownUsingComparator(i, (E) es[i], es, n, cmp);
750		}
751
752		/**
753	<	* Returns the comparator used to order this collection, or <tt>null</tt>
754	<	* if this collection is sorted according to its elements natural ordering
755	<	* (using <tt>Comparable</tt>).
756	<	*
757	<	* @return the comparator used to order this collection, or <tt>null</tt>
758	<	* if this collection is sorted according to its elements natural ordering.
753	>	* Returns the comparator used to order the elements in this
754	>	* queue, or {@code null} if this queue is sorted according to
755	>	* the {@linkplain Comparable natural ordering} of its elements.
756	>	*
757	>	* @return the comparator used to order this queue, or
758	>	*         {@code null} if this queue is sorted according to the
759	>	*         natural ordering of its elements
760		*/
761		public Comparator<? super E> comparator() {
762		return comparator;
763		}
764
765		/**
766	<	* Save the state of the instance to a stream (that
624	<	* is, serialize it).
766	>	* Saves this queue to a stream (that is, serializes it).
767		*
626	–	* @serialData The length of the array backing the instance is
627	–	* emitted (int), followed by all of its elements (each an
628	–	* <tt>Object</tt>) in the proper order.
768		* @param s the stream
769	+	* @throws java.io.IOException if an I/O error occurs
770	+	* @serialData The length of the array backing the instance is
771	+	*             emitted (int), followed by all of its elements
772	+	*             (each an {@code Object}) in the proper order.
773		*/
774		private void writeObject(java.io.ObjectOutputStream s)
775	<	throws java.io.IOException{
775	>	throws java.io.IOException {
776		// Write out element count, and any hidden stuff
777		s.defaultWriteObject();
778
779	<	// Write out array length
780	<	s.writeInt(queue.length);
779	>	// Write out array length, for compatibility with 1.5 version
780	>	s.writeInt(Math.max(2, size + 1));
781
782	<	// Write out all elements in the proper order.
783	<	for (int i=1; i<=size; i++)
784	<	s.writeObject(queue[i]);
782	>	// Write out all elements in the "proper order".
783	>	final Object[] es = queue;
784	>	for (int i = 0, n = size; i < n; i++)
785	>	s.writeObject(es[i]);
786		}
787
788		/**
789	<	* Reconstitute the <tt>ArrayList</tt> instance from a stream (that is,
790	<	* deserialize it).
789	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
790	>	* (that is, deserializes it).
791	>	*
792		* @param s the stream
793	+	* @throws ClassNotFoundException if the class of a serialized object
794	+	*         could not be found
795	+	* @throws java.io.IOException if an I/O error occurs
796		*/
797		private void readObject(java.io.ObjectInputStream s)
798		throws java.io.IOException, ClassNotFoundException {
799		// Read in size, and any hidden stuff
800		s.defaultReadObject();
801
802	<	// Read in array length and allocate array
803	<	int arrayLength = s.readInt();
804	<	queue = new Object[arrayLength];
805	<
806	<	// Read in all elements in the proper order.
807	<	for (int i=1; i<=size; i++)
808	<	queue[i] = (E) s.readObject();
802	>	// Read in (and discard) array length
803	>	s.readInt();
804	>
805	>	SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size);
806	>	final Object[] es = queue = new Object[Math.max(size, 1)];
807	>
808	>	// Read in all elements.
809	>	for (int i = 0, n = size; i < n; i++)
810	>	es[i] = s.readObject();
811	>
812	>	// Elements are guaranteed to be in "proper order", but the
813	>	// spec has never explained what that might be.
814	>	heapify();
815		}
816
817	+	/**
818	+	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
819	+	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
820	+	* queue. The spliterator does not traverse elements in any particular order
821	+	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
822	+	*
823	+	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
824	+	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
825	+	* Overriding implementations should document the reporting of additional
826	+	* characteristic values.
827	+	*
828	+	* @return a {@code Spliterator} over the elements in this queue
829	+	* @since 1.8
830	+	*/
831	+	public final Spliterator<E> spliterator() {
832	+	return new PriorityQueueSpliterator(0, -1, 0);
833	+	}
834	+
835	+	final class PriorityQueueSpliterator implements Spliterator<E> {
836	+	private int index;            // current index, modified on advance/split
837	+	private int fence;            // -1 until first use
838	+	private int expectedModCount; // initialized when fence set
839	+
840	+	/** Creates new spliterator covering the given range. */
841	+	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
842	+	this.index = origin;
843	+	this.fence = fence;
844	+	this.expectedModCount = expectedModCount;
845	+	}
846	+
847	+	private int getFence() { // initialize fence to size on first use
848	+	int hi;
849	+	if ((hi = fence) < 0) {
850	+	expectedModCount = modCount;
851	+	hi = fence = size;
852	+	}
853	+	return hi;
854	+	}
855	+
856	+	public PriorityQueueSpliterator trySplit() {
857	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
858	+	return (lo >= mid) ? null :
859	+	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
860	+	}
861	+
862	+	public void forEachRemaining(Consumer<? super E> action) {
863	+	if (action == null)
864	+	throw new NullPointerException();
865	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
866	+	final Object[] es = queue;
867	+	int i, hi; E e;
868	+	for (i = index, index = hi = fence; i < hi; i++) {
869	+	if ((e = (E) es[i]) == null)
870	+	break;      // must be CME
871	+	action.accept(e);
872	+	}
873	+	if (modCount != expectedModCount)
874	+	throw new ConcurrentModificationException();
875	+	}
876	+
877	+	public boolean tryAdvance(Consumer<? super E> action) {
878	+	if (action == null)
879	+	throw new NullPointerException();
880	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
881	+	int i;
882	+	if ((i = index) < fence) {
883	+	index = i + 1;
884	+	E e;
885	+	if ((e = (E) queue[i]) == null
886	+	|| modCount != expectedModCount)
887	+	throw new ConcurrentModificationException();
888	+	action.accept(e);
889	+	return true;
890	+	}
891	+	return false;
892	+	}
893	+
894	+	public long estimateSize() {
895	+	return getFence() - index;
896	+	}
897	+
898	+	public int characteristics() {
899	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
900	+	}
901	+	}
902	+
903	+	/**
904	+	* @throws NullPointerException {@inheritDoc}
905	+	*/
906	+	public void forEach(Consumer<? super E> action) {
907	+	Objects.requireNonNull(action);
908	+	final int expectedModCount = modCount;
909	+	final Object[] es = queue;
910	+	for (int i = 0, n = size; i < n; i++)
911	+	action.accept((E) es[i]);
912	+	if (expectedModCount != modCount)
913	+	throw new ConcurrentModificationException();
914	+	}
915		}

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