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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.54 by jsr166, Thu Nov 24 03:44:57 2005 UTC vs.
Revision 1.124 by jsr166, Sun May 6 19:35:51 2018 UTC

#	Line 1 | Line 1
1		/*
2	<	* @(#)PriorityQueue.java       1.8 05/08/27
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 2005 Sun Microsystems, Inc. All rights reserved.
6	<	* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
5	>	* This code is free software; you can redistribute it and/or modify it
6	>	* under the terms of the GNU General Public License version 2 only, as
7	>	* published by the Free Software Foundation.  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	<	import java.util.*; // for javadoc (till 6280605 is fixed)
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.  The elements of the priority queue are ordered according to
34	<	* their {@linkplain Comparable natural ordering}, or by a {@link
35	<	* Comparator} provided at queue construction time, depending on which
36	<	* constructor is used.  A priority queue does not permit
37	<	* <tt>null</tt> elements.  A priority queue relying on natural
38	<	* ordering also does not permit insertion of non-comparable objects
39	<	* (doing so may result in <tt>ClassCastException</tt>).
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 queue retrieval operations <tt>poll</tt>,
45	<	* <tt>remove</tt>, <tt>peek</tt>, and <tt>element</tt> access the
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
#	Line 35 | Line 55 | import java.util.*; // for javadoc (till
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()} is <em>not</em> guaranteed to traverse the elements of
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 <tt>Arrays.sort(pq.toArray())</tt>.
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 <tt>PriorityQueue</tt>
65	<	* instance concurrently if any of the threads modifies the list
66	<	* structurally. Instead, use the thread-safe {@link
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	<	* <p>Implementation note: this implementation provides O(log(n)) time
70	<	* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>,
71	<	* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the
72	<	* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and
73	<	* constant time for the retrieval methods (<tt>peek</tt>,
74	<	* <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 1.8, 08/27/05
82	<	* @author Josh Bloch
61	<	* @param <E> the type of elements held in this collection
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 java.io.Serializable {
87
#	Line 68 | Line 90 | public class PriorityQueue<E> extends Ab
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	<	*
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.
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 97 | 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
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		*/
#	Line 109 | Line 126 | public class PriorityQueue<E> extends Ab
126		}
127
128		/**
129	<	* Creates a <tt>PriorityQueue</tt> with the specified initial
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 <tt>initialCapacity</tt> is less
135	<	* than 1
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 that will be used to order
160	<	*         this priority queue.  If <tt>null</tt>, the <i>natural
161	<	*         ordering</i> of the elements will be used.
162	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is
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,
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.
178	<	*/
179	<	private void initializeArray(Collection<? extends E> c) {
180	<	int sz = c.size();
181	<	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	<	/**
187	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
188	<	* 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
191	<	* instance of a {@link java.util.SortedSet} or is another
192	<	* <tt>PriorityQueue</tt>, the priority queue will be ordered
193	<	* according to the same ordering.  Otherwise, this priority queue
194	<	* will be ordered according to the natural ordering of its elements.
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
#	Line 202 | Line 189 | public class PriorityQueue<E> extends Ab
189		*         of its elements are null
190		*/
191		public PriorityQueue(Collection<? extends E> c) {
192	<	initializeArray(c);
193	<	if (c instanceof SortedSet) {
194	<	SortedSet<? extends E> s = (SortedSet<? extends E>)c;
195	<	comparator = (Comparator<? super E>)s.comparator();
196	<	fillFromSorted(s);
197	<	} else if (c instanceof PriorityQueue) {
198	<	PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c;
199	<	comparator = (Comparator<? super E>)s.comparator();
200	<	fillFromSorted(s);
201	<	} else {
202	<	comparator = null;
203	<	fillFromUnsorted(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	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
210	<	* 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
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 <tt>c</tt> cannot be
217	<	*         compared to one another according to <tt>c</tt>'s
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		public PriorityQueue(PriorityQueue<? extends E> c) {
223	<	initializeArray(c);
224	<	comparator = (Comparator<? super E>)c.comparator();
239	<	fillFromSorted(c);
223	>	this.comparator = (Comparator<? super E>) c.comparator();
224	>	initFromPriorityQueue(c);
225		}
226
227		/**
228	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
229	<	* 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
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.
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
#	Line 255 | Line 238 | public class PriorityQueue<E> extends Ab
238		*         of its elements are null
239		*/
240		public PriorityQueue(SortedSet<? extends E> c) {
241	<	initializeArray(c);
242	<	comparator = (Comparator<? super E>)c.comparator();
243	<	fillFromSorted(c);
241	>	this.comparator = (Comparator<? super E>) c.comparator();
242	>	initElementsFromCollection(c);
243	>	}
244	>
245	>	private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
246	>	if (c.getClass() == PriorityQueue.class) {
247	>	this.queue = c.toArray();
248	>	this.size = c.size();
249	>	} else {
250	>	initFromCollection(c);
251	>	}
252	>	}
253	>
254	>	private void initElementsFromCollection(Collection<? extends E> c) {
255	>	Object[] es = c.toArray();
256	>	int len = es.length;
257	>	// If c.toArray incorrectly doesn't return Object[], copy it.
258	>	if (es.getClass() != Object[].class)
259	>	es = Arrays.copyOf(es, len, Object[].class);
260	>	if (len == 1 || this.comparator != null)
261	>	for (Object e : es)
262	>	if (e == null)
263	>	throw new NullPointerException();
264	>	this.queue = es;
265	>	this.size = len;
266	>	}
267	>
268	>	/**
269	>	* Initializes queue array with elements from the given Collection.
270	>	*
271	>	* @param c the collection
272	>	*/
273	>	private void initFromCollection(Collection<? extends E> c) {
274	>	initElementsFromCollection(c);
275	>	heapify();
276		}
277
278		/**
279	<	* Resize array, if necessary, to be able to hold given index.
279	>	* The maximum size of array to allocate.
280	>	* Some VMs reserve some header words in an array.
281	>	* Attempts to allocate larger arrays may result in
282	>	* OutOfMemoryError: Requested array size exceeds VM limit
283		*/
284	<	private void grow(int index) {
285	<	int newlen = queue.length;
286	<	if (index < newlen) // don't need to grow
287	<	return;
288	<	if (index == Integer.MAX_VALUE)
284	>	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
285	>
286	>	/**
287	>	* Increases the capacity of the array.
288	>	*
289	>	* @param minCapacity the desired minimum capacity
290	>	*/
291	>	private void grow(int minCapacity) {
292	>	int oldCapacity = queue.length;
293	>	// Double size if small; else grow by 50%
294	>	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
295	>	(oldCapacity + 2) :
296	>	(oldCapacity >> 1));
297	>	// overflow-conscious code
298	>	if (newCapacity - MAX_ARRAY_SIZE > 0)
299	>	newCapacity = hugeCapacity(minCapacity);
300	>	queue = Arrays.copyOf(queue, newCapacity);
301	>	}
302	>
303	>	private static int hugeCapacity(int minCapacity) {
304	>	if (minCapacity < 0) // overflow
305		throw new OutOfMemoryError();
306	<	while (newlen <= index) {
307	<	if (newlen >= Integer.MAX_VALUE / 2)  // avoid overflow
308	<	newlen = Integer.MAX_VALUE;
275	<	else
276	<	newlen <<= 1;
277	<	}
278	<	queue = Arrays.copyOf(queue, newlen);
306	>	return (minCapacity > MAX_ARRAY_SIZE) ?
307	>	Integer.MAX_VALUE :
308	>	MAX_ARRAY_SIZE;
309		}
310
311		/**
312		* Inserts the specified element into this priority queue.
313		*
314	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
314	>	* @return {@code true} (as specified by {@link Collection#add})
315		* @throws ClassCastException if the specified element cannot be
316		*         compared with elements currently in this priority queue
317		*         according to the priority queue's ordering
#	Line 294 | Line 324 | public class PriorityQueue<E> extends Ab
324		/**
325		* Inserts the specified element into this priority queue.
326		*
327	<	* @return <tt>true</tt> (as specified by {@link Queue#offer})
327	>	* @return {@code true} (as specified by {@link Queue#offer})
328		* @throws ClassCastException if the specified element cannot be
329		*         compared with elements currently in this priority queue
330		*         according to the priority queue's ordering
#	Line 304 | Line 334 | public class PriorityQueue<E> extends Ab
334		if (e == null)
335		throw new NullPointerException();
336		modCount++;
337	<	++size;
338	<
339	<	// Grow backing store if necessary
340	<	if (size >= queue.length)
341	<	grow(size);
312	<
313	<	queue[size] = e;
314	<	fixUp(size);
337	>	int i = size;
338	>	if (i >= queue.length)
339	>	grow(i + 1);
340	>	siftUp(i, e);
341	>	size = i + 1;
342		return true;
343		}
344
345		public E peek() {
346	<	if (size == 0)
320	<	return null;
321	<	return (E) queue[1];
346	>	return (size == 0) ? null : (E) queue[0];
347		}
348
349		private int indexOf(Object o) {
350	<	if (o == null)
351	<	return -1;
352	<	for (int i = 1; i <= size; i++)
353	<	if (o.equals(queue[i]))
354	<	return i;
350	>	if (o != null) {
351	>	final Object[] es = queue;
352	>	for (int i = 0, n = size; i < n; i++)
353	>	if (o.equals(es[i]))
354	>	return i;
355	>	}
356		return -1;
357		}
358
359		/**
360		* Removes a single instance of the specified element from this queue,
361	<	* if it is present.  More formally, removes an element <tt>e</tt> such
362	<	* that <tt>o.equals(e)</tt>, if this queue contains one or more such
363	<	* elements.  Returns true if this queue contained the specified element
364	<	* (or equivalently, if this queue changed as a result of the call).
361	>	* if it is present.  More formally, removes an element {@code e} such
362	>	* that {@code o.equals(e)}, if this queue contains one or more such
363	>	* elements.  Returns {@code true} if and only if this queue contained
364	>	* the specified element (or equivalently, if this queue changed as a
365	>	* result of the call).
366		*
367		* @param o element to be removed from this queue, if present
368	<	* @return <tt>true</tt> if this queue changed as a result of the call
368	>	* @return {@code true} if this queue changed as a result of the call
369		*/
370		public boolean remove(Object o) {
371	<	int i = indexOf(o);
372	<	if (i == -1)
373	<	return false;
374	<	else {
375	<	removeAt(i);
376	<	return true;
377	<	}
371	>	int i = indexOf(o);
372	>	if (i == -1)
373	>	return false;
374	>	else {
375	>	removeAt(i);
376	>	return true;
377	>	}
378		}
379
380		/**
381	<	* Returns <tt>true</tt> if this queue contains the specified element.
382	<	* More formally, returns <tt>true</tt> if and only if this queue contains
383	<	* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
381	>	* Identity-based version for use in Itr.remove.
382	>	*
383	>	* @param o element to be removed from this queue, if present
384	>	*/
385	>	void removeEq(Object o) {
386	>	final Object[] es = queue;
387	>	for (int i = 0, n = size; i < n; i++) {
388	>	if (o == es[i]) {
389	>	removeAt(i);
390	>	break;
391	>	}
392	>	}
393	>	}
394	>
395	>	/**
396	>	* Returns {@code true} if this queue contains the specified element.
397	>	* More formally, returns {@code true} if and only if this queue contains
398	>	* at least one element {@code e} such that {@code o.equals(e)}.
399		*
400		* @param o object to be checked for containment in this queue
401	<	* @return <tt>true</tt> if this queue contains the specified element
401	>	* @return {@code true} if this queue contains the specified element
402		*/
403		public boolean contains(Object o) {
404	<	return indexOf(o) != -1;
404	>	return indexOf(o) >= 0;
405		}
406
407		/**
408	<	* Returns an array containing all of the elements in this queue,
408	>	* Returns an array containing all of the elements in this queue.
409		* The elements are in no particular order.
410		*
411		* <p>The returned array will be "safe" in that no references to it are
412	<	* maintained by this list.  (In other words, this method must allocate
412	>	* maintained by this queue.  (In other words, this method must allocate
413		* a new array).  The caller is thus free to modify the returned array.
414		*
415	<	* @return an array containing all of the elements in this queue.
415	>	* <p>This method acts as bridge between array-based and collection-based
416	>	* APIs.
417	>	*
418	>	* @return an array containing all of the elements in this queue
419		*/
420		public Object[] toArray() {
421	<	return Arrays.copyOfRange(queue, 1, size+1);
421	>	return Arrays.copyOf(queue, size);
422		}
423
424		/**
425	<	* Returns an array containing all of the elements in this queue.
426	<	* The elements are in no particular order.  The runtime type of
427	<	* the returned array is that of the specified array.  If the queue
428	<	* fits in the specified array, it is returned therein.
429	<	* Otherwise, a new array is allocated with the runtime type of
430	<	* the specified array and the size of this queue.
425	>	* Returns an array containing all of the elements in this queue; the
426	>	* runtime type of the returned array is that of the specified array.
427	>	* The returned array elements are in no particular order.
428	>	* If the queue fits in the specified array, it is returned therein.
429	>	* Otherwise, a new array is allocated with the runtime type of the
430	>	* specified array and the size of this queue.
431		*
432		* <p>If the queue fits in the specified array with room to spare
433		* (i.e., the array has more elements than the queue), the element in
434		* the array immediately following the end of the collection is set to
435	<	* <tt>null</tt>.  (This is useful in determining the length of the
436	<	* queue <i>only</i> if the caller knows that the queue does not contain
437	<	* any null elements.)
435	>	* {@code null}.
436	>	*
437	>	* <p>Like the {@link #toArray()} method, this method acts as bridge between
438	>	* array-based and collection-based APIs.  Further, this method allows
439	>	* precise control over the runtime type of the output array, and may,
440	>	* under certain circumstances, be used to save allocation costs.
441	>	*
442	>	* <p>Suppose {@code x} is a queue known to contain only strings.
443	>	* The following code can be used to dump the queue into a newly
444	>	* allocated array of {@code String}:
445	>	*
446	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
447	>	*
448	>	* Note that {@code toArray(new Object[0])} is identical in function to
449	>	* {@code toArray()}.
450		*
451		* @param a the array into which the elements of the queue are to
452		*          be stored, if it is big enough; otherwise, a new array of the
453		*          same runtime type is allocated for this purpose.
454	<	* @return an array containing the elements of the queue
454	>	* @return an array containing all of the elements in this queue
455		* @throws ArrayStoreException if the runtime type of the specified array
456		*         is not a supertype of the runtime type of every element in
457		*         this queue
458		* @throws NullPointerException if the specified array is null
459		*/
460		public <T> T[] toArray(T[] a) {
461	+	final int size = this.size;
462		if (a.length < size)
463		// Make a new array of a's runtime type, but my contents:
464	<	return (T[]) Arrays.copyOfRange(queue, 1, size+1, a.getClass());
465	<	System.arraycopy(queue, 1, a, 0, size);
464	>	return (T[]) Arrays.copyOf(queue, size, a.getClass());
465	>	System.arraycopy(queue, 0, a, 0, size);
466		if (a.length > size)
467		a[size] = null;
468		return a;
#	Line 420 | Line 478 | public class PriorityQueue<E> extends Ab
478		return new Itr();
479		}
480
481	<	private class Itr implements Iterator<E> {
424	<
481	>	private final class Itr implements Iterator<E> {
482		/**
483		* Index (into queue array) of element to be returned by
484		* subsequent call to next.
485		*/
486	<	private int cursor = 1;
486	>	private int cursor;
487
488		/**
489		* Index of element returned by most recent call to next,
490		* unless that element came from the forgetMeNot list.
491	<	* Reset to 0 if element is deleted by a call to remove.
491	>	* Set to -1 if element is deleted by a call to remove.
492		*/
493	<	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.
442	<	*/
443	<	private int expectedModCount = modCount;
493	>	private int lastRet = -1;
494
495		/**
496	<	* A list of elements that were moved from the unvisited portion of
496	>	* A queue of elements that were moved from the unvisited portion of
497		* the heap into the visited portion as a result of "unlucky" element
498		* removals during the iteration.  (Unlucky element removals are those
499	<	* that require a fixup instead of a fixdown.)  We must visit all of
499	>	* that require a siftup instead of a siftdown.)  We must visit all of
500		* the elements in this list to complete the iteration.  We do this
501		* after we've completed the "normal" iteration.
502		*
503		* We expect that most iterations, even those involving removals,
504	<	* will not use need to store elements in this field.
504	>	* will not need to store elements in this field.
505		*/
506	<	private ArrayList<E> forgetMeNot = null;
506	>	private ArrayDeque<E> forgetMeNot;
507
508		/**
509		* Element returned by the most recent call to next iff that
510		* element was drawn from the forgetMeNot list.
511		*/
512	<	private Object lastRetElt = null;
512	>	private E lastRetElt;
513	>
514	>	/**
515	>	* The modCount value that the iterator believes that the backing
516	>	* Queue should have.  If this expectation is violated, the iterator
517	>	* has detected concurrent modification.
518	>	*/
519	>	private int expectedModCount = modCount;
520	>
521	>	Itr() {}                        // prevent access constructor creation
522
523		public boolean hasNext() {
524	<	return cursor <= size || forgetMeNot != null;
524	>	return cursor < size ||
525	>	(forgetMeNot != null && !forgetMeNot.isEmpty());
526		}
527
528		public E next() {
529	<	checkForComodification();
530	<	E result;
531	<	if (cursor <= size) {
532	<	result = (E) queue[cursor];
533	<	lastRet = cursor++;
534	<	}
535	<	else if (forgetMeNot == null)
536	<	throw new NoSuchElementException();
537	<	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;
529	>	if (expectedModCount != modCount)
530	>	throw new ConcurrentModificationException();
531	>	if (cursor < size)
532	>	return (E) queue[lastRet = cursor++];
533	>	if (forgetMeNot != null) {
534	>	lastRet = -1;
535	>	lastRetElt = forgetMeNot.poll();
536	>	if (lastRetElt != null)
537	>	return lastRetElt;
538		}
539	<	return result;
539	>	throw new NoSuchElementException();
540		}
541
542		public void remove() {
543	<	checkForComodification();
544	<
545	<	if (lastRet != 0) {
543	>	if (expectedModCount != modCount)
544	>	throw new ConcurrentModificationException();
545	>	if (lastRet != -1) {
546		E moved = PriorityQueue.this.removeAt(lastRet);
547	<	lastRet = 0;
548	<	if (moved == null) {
547	>	lastRet = -1;
548	>	if (moved == null)
549		cursor--;
550	<	} else {
550	>	else {
551		if (forgetMeNot == null)
552	<	forgetMeNot = new ArrayList<E>();
552	>	forgetMeNot = new ArrayDeque<>();
553		forgetMeNot.add(moved);
554		}
555		} else if (lastRetElt != null) {
556	<	PriorityQueue.this.remove(lastRetElt);
556	>	PriorityQueue.this.removeEq(lastRetElt);
557		lastRetElt = null;
558		} else {
559		throw new IllegalStateException();
560		}
507	–
561		expectedModCount = modCount;
562		}
510	–
511	–	final void checkForComodification() {
512	–	if (modCount != expectedModCount)
513	–	throw new ConcurrentModificationException();
514	–	}
563		}
564
565		public int size() {
#	Line 524 | Line 572 | public class PriorityQueue<E> extends Ab
572		*/
573		public void clear() {
574		modCount++;
575	<
576	<	// Null out element references to prevent memory leak
577	<	for (int i=1; i<=size; i++)
530	<	queue[i] = null;
531	<
575	>	final Object[] es = queue;
576	>	for (int i = 0, n = size; i < n; i++)
577	>	es[i] = null;
578		size = 0;
579		}
580
581		public E poll() {
582		if (size == 0)
583		return null;
584	+	int s = --size;
585		modCount++;
586	<
587	<	E result = (E) queue[1];
588	<	queue[1] = queue[size];
589	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
590	<	if (size > 1)
544	<	fixDown(1);
545	<
586	>	E result = (E) queue[0];
587	>	E x = (E) queue[s];
588	>	queue[s] = null;
589	>	if (s != 0)
590	>	siftDown(0, x);
591		return result;
592		}
593
594		/**
595	<	* Removes and returns the ith element from queue.  (Recall that queue
551	<	* is one-based, so 1 <= i <= size.)
595	>	* Removes the ith element from queue.
596		*
597	<	* Normally this method leaves the elements at positions from 1 up to i-1,
598	<	* inclusive, untouched.  Under these circumstances, it returns null.
599	<	* Occasionally, in order to maintain the heap invariant, it must move
600	<	* the last element of the list to some index in the range [2, i-1],
601	<	* and move the element previously at position (i/2) to position i.
602	<	* Under these circumstances, this method returns the element that was
603	<	* previously at the end of the list and is now at some position between
604	<	* 2 and i-1 inclusive.
597	>	* Normally this method leaves the elements at up to i-1,
598	>	* inclusive, untouched.  Under these circumstances, it returns
599	>	* null.  Occasionally, in order to maintain the heap invariant,
600	>	* it must swap a later element of the list with one earlier than
601	>	* i.  Under these circumstances, this method returns the element
602	>	* that was previously at the end of the list and is now at some
603	>	* position before i. This fact is used by iterator.remove so as to
604	>	* avoid missing traversing elements.
605		*/
606	<	private E removeAt(int i) {
607	<	assert i > 0 && i <= size;
606	>	E removeAt(int i) {
607	>	// assert i >= 0 && i < size;
608		modCount++;
609	<
610	<	E moved = (E) queue[size];
611	<	queue[i] = moved;
612	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
613	<	if (i <= size) {
614	<	fixDown(i);
609	>	int s = --size;
610	>	if (s == i) // removed last element
611	>	queue[i] = null;
612	>	else {
613	>	E moved = (E) queue[s];
614	>	queue[s] = null;
615	>	siftDown(i, moved);
616		if (queue[i] == moved) {
617	<	fixUp(i);
617	>	siftUp(i, moved);
618		if (queue[i] != moved)
619		return moved;
620		}
#	Line 578 | Line 623 | public class PriorityQueue<E> extends Ab
623		}
624
625		/**
626	<	* Establishes the heap invariant (described above) assuming the heap
627	<	* satisfies the invariant except possibly for the leaf-node indexed by k
628	<	* (which may have a nextExecutionTime less than its parent's).
629	<	*
630	<	* This method functions by "promoting" queue[k] up the hierarchy
631	<	* (by swapping it with its parent) repeatedly until queue[k]
632	<	* is greater than or equal to its parent.
633	<	*/
634	<	private void fixUp(int k) {
635	<	if (comparator == null) {
636	<	while (k > 1) {
637	<	int j = k >> 1;
638	<	if (((Comparable<? super E>)queue[j]).compareTo((E)queue[k]) <= 0)
639	<	break;
640	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
641	<	k = j;
642	<	}
643	<	} else {
644	<	while (k > 1) {
645	<	int j = k >>> 1;
646	<	if (comparator.compare((E)queue[j], (E)queue[k]) <= 0)
647	<	break;
648	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
649	<	k = j;
650	<	}
651	<	}
652	<	}
653	<
654	<	/**
655	<	* Establishes the heap invariant (described above) in the subtree
656	<	* rooted at k, which is assumed to satisfy the heap invariant except
657	<	* possibly for node k itself (which may be greater than its children).
658	<	*
659	<	* This method functions by "demoting" queue[k] down the hierarchy
660	<	* (by swapping it with its smaller child) repeatedly until queue[k]
661	<	* is less than or equal to its children.
662	<	*/
663	<	private void fixDown(int k) {
664	<	int j;
665	<	if (comparator == null) {
666	<	while ((j = k << 1) <= size && (j > 0)) {
667	<	if (j<size &&
668	<	((Comparable<? super E>)queue[j]).compareTo((E)queue[j+1]) > 0)
669	<	j++; // j indexes smallest kid
670	<
671	<	if (((Comparable<? super E>)queue[k]).compareTo((E)queue[j]) <= 0)
672	<	break;
673	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
674	<	k = j;
675	<	}
676	<	} else {
677	<	while ((j = k << 1) <= size && (j > 0)) {
678	<	if (j<size &&
679	<	comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
680	<	j++; // j indexes smallest kid
681	<	if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
682	<	break;
683	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
684	<	k = j;
685	<	}
626	>	* Inserts item x at position k, maintaining heap invariant by
627	>	* promoting x up the tree until it is greater than or equal to
628	>	* its parent, or is the root.
629	>	*
630	>	* To simplify and speed up coercions and comparisons, the
631	>	* Comparable and Comparator versions are separated into different
632	>	* methods that are otherwise identical. (Similarly for siftDown.)
633	>	*
634	>	* @param k the position to fill
635	>	* @param x the item to insert
636	>	*/
637	>	private void siftUp(int k, E x) {
638	>	if (comparator != null)
639	>	siftUpUsingComparator(k, x, queue, comparator);
640	>	else
641	>	siftUpComparable(k, x, queue);
642	>	}
643	>
644	>	private static <T> void siftUpComparable(int k, T x, Object[] es) {
645	>	Comparable<? super T> key = (Comparable<? super T>) x;
646	>	while (k > 0) {
647	>	int parent = (k - 1) >>> 1;
648	>	Object e = es[parent];
649	>	if (key.compareTo((T) e) >= 0)
650	>	break;
651	>	es[k] = e;
652	>	k = parent;
653	>	}
654	>	es[k] = key;
655	>	}
656	>
657	>	private static <T> void siftUpUsingComparator(
658	>	int k, T x, Object[] es, Comparator<? super T> cmp) {
659	>	while (k > 0) {
660	>	int parent = (k - 1) >>> 1;
661	>	Object e = es[parent];
662	>	if (cmp.compare(x, (T) e) >= 0)
663	>	break;
664	>	es[k] = e;
665	>	k = parent;
666	>	}
667	>	es[k] = x;
668	>	}
669	>
670	>	/**
671	>	* Inserts item x at position k, maintaining heap invariant by
672	>	* demoting x down the tree repeatedly until it is less than or
673	>	* equal to its children or is a leaf.
674	>	*
675	>	* @param k the position to fill
676	>	* @param x the item to insert
677	>	*/
678	>	private void siftDown(int k, E x) {
679	>	if (comparator != null)
680	>	siftDownUsingComparator(k, x, queue, size, comparator);
681	>	else
682	>	siftDownComparable(k, x, queue, size);
683	>	}
684	>
685	>	private static <T> void siftDownComparable(int k, T x, Object[] es, int n) {
686	>	// assert n > 0;
687	>	Comparable<? super T> key = (Comparable<? super T>)x;
688	>	int half = n >>> 1;           // loop while a non-leaf
689	>	while (k < half) {
690	>	int child = (k << 1) + 1; // assume left child is least
691	>	Object c = es[child];
692	>	int right = child + 1;
693	>	if (right < n &&
694	>	((Comparable<? super T>) c).compareTo((T) es[right]) > 0)
695	>	c = es[child = right];
696	>	if (key.compareTo((T) c) <= 0)
697	>	break;
698	>	es[k] = c;
699	>	k = child;
700	>	}
701	>	es[k] = key;
702	>	}
703	>
704	>	private static <T> void siftDownUsingComparator(
705	>	int k, T x, Object[] es, int n, Comparator<? super T> cmp) {
706	>	// assert n > 0;
707	>	int half = n >>> 1;
708	>	while (k < half) {
709	>	int child = (k << 1) + 1;
710	>	Object c = es[child];
711	>	int right = child + 1;
712	>	if (right < n && cmp.compare((T) c, (T) es[right]) > 0)
713	>	c = es[child = right];
714	>	if (cmp.compare(x, (T) c) <= 0)
715	>	break;
716	>	es[k] = c;
717	>	k = child;
718		}
719	+	es[k] = x;
720		}
721
722		/**
723		* Establishes the heap invariant (described above) in the entire tree,
724		* assuming nothing about the order of the elements prior to the call.
725	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
726		*/
727		private void heapify() {
728	<	for (int i = size/2; i >= 1; i--)
729	<	fixDown(i);
728	>	final Object[] es = queue;
729	>	int n = size, i = (n >>> 1) - 1;
730	>	Comparator<? super E> cmp = comparator;
731	>	if (cmp == null)
732	>	for (; i >= 0; i--)
733	>	siftDownComparable(i, (E) es[i], es, n);
734	>	else
735	>	for (; i >= 0; i--)
736	>	siftDownUsingComparator(i, (E) es[i], es, n, cmp);
737		}
738
739		/**
740		* Returns the comparator used to order the elements in this
741	<	* queue, or <tt>null</tt> if this queue is sorted according to
741	>	* queue, or {@code null} if this queue is sorted according to
742		* the {@linkplain Comparable natural ordering} of its elements.
743		*
744		* @return the comparator used to order this queue, or
745	<	*         <tt>null</tt> if this queue is sorted according to the
746	<	*         natural ordering of its elements.
745	>	*         {@code null} if this queue is sorted according to the
746	>	*         natural ordering of its elements
747		*/
748		public Comparator<? super E> comparator() {
749		return comparator;
750		}
751
752		/**
753	<	* Save the state of the instance to a stream (that
668	<	* is, serialize it).
753	>	* Saves this queue to a stream (that is, serializes it).
754		*
670	–	* @serialData The length of the array backing the instance is
671	–	* emitted (int), followed by all of its elements (each an
672	–	* <tt>Object</tt>) in the proper order.
755		* @param s the stream
756	+	* @throws java.io.IOException if an I/O error occurs
757	+	* @serialData The length of the array backing the instance is
758	+	*             emitted (int), followed by all of its elements
759	+	*             (each an {@code Object}) in the proper order.
760		*/
761		private void writeObject(java.io.ObjectOutputStream s)
762	<	throws java.io.IOException{
762	>	throws java.io.IOException {
763		// Write out element count, and any hidden stuff
764		s.defaultWriteObject();
765
766	<	// Write out array length
767	<	s.writeInt(queue.length);
766	>	// Write out array length, for compatibility with 1.5 version
767	>	s.writeInt(Math.max(2, size + 1));
768
769	<	// Write out all elements in the proper order.
770	<	for (int i=1; i<=size; i++)
771	<	s.writeObject(queue[i]);
769	>	// Write out all elements in the "proper order".
770	>	final Object[] es = queue;
771	>	for (int i = 0, n = size; i < n; i++)
772	>	s.writeObject(es[i]);
773		}
774
775		/**
776	<	* Reconstitute the <tt>PriorityQueue</tt> instance from a stream
777	<	* (that is, deserialize it).
776	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
777	>	* (that is, deserializes it).
778	>	*
779		* @param s the stream
780	+	* @throws ClassNotFoundException if the class of a serialized object
781	+	*         could not be found
782	+	* @throws java.io.IOException if an I/O error occurs
783		*/
784		private void readObject(java.io.ObjectInputStream s)
785		throws java.io.IOException, ClassNotFoundException {
786		// Read in size, and any hidden stuff
787		s.defaultReadObject();
788
789	<	// Read in array length and allocate array
790	<	int arrayLength = s.readInt();
791	<	queue = new Object[arrayLength];
792	<
793	<	// Read in all elements in the proper order.
794	<	for (int i=1; i<=size; i++)
795	<	queue[i] = (E) s.readObject();
789	>	// Read in (and discard) array length
790	>	s.readInt();
791	>
792	>	SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size);
793	>	queue = new Object[size];
794	>
795	>	// Read in all elements.
796	>	final Object[] es = queue;
797	>	for (int i = 0, n = size; i < n; i++)
798	>	es[i] = s.readObject();
799	>
800	>	// Elements are guaranteed to be in "proper order", but the
801	>	// spec has never explained what that might be.
802	>	heapify();
803	>	}
804	>
805	>	/**
806	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
807	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
808	>	* queue. The spliterator does not traverse elements in any particular order
809	>	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
810	>	*
811	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
812	>	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
813	>	* Overriding implementations should document the reporting of additional
814	>	* characteristic values.
815	>	*
816	>	* @return a {@code Spliterator} over the elements in this queue
817	>	* @since 1.8
818	>	*/
819	>	public final Spliterator<E> spliterator() {
820	>	return new PriorityQueueSpliterator(0, -1, 0);
821	>	}
822	>
823	>	final class PriorityQueueSpliterator implements Spliterator<E> {
824	>	private int index;            // current index, modified on advance/split
825	>	private int fence;            // -1 until first use
826	>	private int expectedModCount; // initialized when fence set
827	>
828	>	/** Creates new spliterator covering the given range. */
829	>	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
830	>	this.index = origin;
831	>	this.fence = fence;
832	>	this.expectedModCount = expectedModCount;
833	>	}
834	>
835	>	private int getFence() { // initialize fence to size on first use
836	>	int hi;
837	>	if ((hi = fence) < 0) {
838	>	expectedModCount = modCount;
839	>	hi = fence = size;
840	>	}
841	>	return hi;
842	>	}
843	>
844	>	public PriorityQueueSpliterator trySplit() {
845	>	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
846	>	return (lo >= mid) ? null :
847	>	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
848	>	}
849	>
850	>	public void forEachRemaining(Consumer<? super E> action) {
851	>	if (action == null)
852	>	throw new NullPointerException();
853	>	if (fence < 0) { fence = size; expectedModCount = modCount; }
854	>	final Object[] es = queue;
855	>	int i, hi; E e;
856	>	for (i = index, index = hi = fence; i < hi; i++) {
857	>	if ((e = (E) es[i]) == null)
858	>	break;      // must be CME
859	>	action.accept(e);
860	>	}
861	>	if (modCount != expectedModCount)
862	>	throw new ConcurrentModificationException();
863	>	}
864	>
865	>	public boolean tryAdvance(Consumer<? super E> action) {
866	>	if (action == null)
867	>	throw new NullPointerException();
868	>	if (fence < 0) { fence = size; expectedModCount = modCount; }
869	>	int i;
870	>	if ((i = index) < fence) {
871	>	index = i + 1;
872	>	E e;
873	>	if ((e = (E) queue[i]) == null
874	>	|| modCount != expectedModCount)
875	>	throw new ConcurrentModificationException();
876	>	action.accept(e);
877	>	return true;
878	>	}
879	>	return false;
880	>	}
881	>
882	>	public long estimateSize() {
883	>	return getFence() - index;
884	>	}
885	>
886	>	public int characteristics() {
887	>	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
888	>	}
889		}
890
891	+	/**
892	+	* @throws NullPointerException {@inheritDoc}
893	+	*/
894	+	public void forEach(Consumer<? super E> action) {
895	+	Objects.requireNonNull(action);
896	+	final int expectedModCount = modCount;
897	+	final Object[] es = queue;
898	+	for (int i = 0, n = size; i < n; i++)
899	+	action.accept((E) es[i]);
900	+	if (expectedModCount != modCount)
901	+	throw new ConcurrentModificationException();
902	+	}
903		}

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