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/* |
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* @(#)PriorityQueue.java 1.8 05/08/27 |
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* Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* Copyright 2005 Sun Microsystems, Inc. All rights reserved. |
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* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package java.util; |
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import java.util.*; // for javadoc (till 6280605 is fixed) |
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|
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import java.util.function.Consumer; |
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import jdk.internal.misc.SharedSecrets; |
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|
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/** |
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* An unbounded priority {@linkplain Queue queue} based on a priority |
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* heap. The elements of the priority queue are ordered according to |
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* their {@linkplain Comparable natural ordering}, or by a {@link |
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* Comparator} provided at queue construction time, depending on which |
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* constructor is used. A priority queue does not permit |
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* <tt>null</tt> elements. A priority queue relying on natural |
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* ordering also does not permit insertion of non-comparable objects |
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* (doing so may result in <tt>ClassCastException</tt>). |
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* An unbounded priority {@linkplain Queue queue} based on a priority heap. |
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* The elements of the priority queue are ordered according to their |
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* {@linkplain Comparable natural ordering}, or by a {@link Comparator} |
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* provided at queue construction time, depending on which constructor is |
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* used. A priority queue does not permit {@code null} elements. |
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* A priority queue relying on natural ordering also does not permit |
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* insertion of non-comparable objects (doing so may result in |
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* {@code ClassCastException}). |
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* |
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* <p>The <em>head</em> of this queue is the <em>least</em> element |
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* with respect to the specified ordering. If multiple elements are |
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* tied for least value, the head is one of those elements -- ties are |
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* broken arbitrarily. The queue retrieval operations <tt>poll</tt>, |
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* <tt>remove</tt>, <tt>peek</tt>, and <tt>element</tt> access the |
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* broken arbitrarily. The queue retrieval operations {@code poll}, |
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* {@code remove}, {@code peek}, and {@code element} access the |
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* element at the head of the queue. |
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* |
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* <p>A priority queue is unbounded, but has an internal |
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* <p>This class and its iterator implement all of the |
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* <em>optional</em> methods of the {@link Collection} and {@link |
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* Iterator} interfaces. The Iterator provided in method {@link |
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* #iterator()} is <em>not</em> guaranteed to traverse the elements of |
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* #iterator()} and the Spliterator provided in method {@link #spliterator()} |
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* are <em>not</em> guaranteed to traverse the elements of |
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* the priority queue in any particular order. If you need ordered |
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* traversal, consider using <tt>Arrays.sort(pq.toArray())</tt>. |
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* traversal, consider using {@code Arrays.sort(pq.toArray())}. |
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* |
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* <p> <strong>Note that this implementation is not synchronized.</strong> |
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* Multiple threads should not access a <tt>PriorityQueue</tt> |
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* instance concurrently if any of the threads modifies the list |
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* structurally. Instead, use the thread-safe {@link |
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* <p><strong>Note that this implementation is not synchronized.</strong> |
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* Multiple threads should not access a {@code PriorityQueue} |
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* instance concurrently if any of the threads modifies the queue. |
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* Instead, use the thread-safe {@link |
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* java.util.concurrent.PriorityBlockingQueue} class. |
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* |
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* <p>Implementation note: this implementation provides O(log(n)) time |
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* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>, |
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* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the |
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* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and |
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* constant time for the retrieval methods (<tt>peek</tt>, |
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* <tt>element</tt>, and <tt>size</tt>). |
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* <p>Implementation note: this implementation provides |
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* O(log(n)) time for the enqueuing and dequeuing methods |
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* ({@code offer}, {@code poll}, {@code remove()} and {@code add}); |
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* linear time for the {@code remove(Object)} and {@code contains(Object)} |
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* methods; and constant time for the retrieval methods |
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* ({@code peek}, {@code element}, and {@code size}). |
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* |
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* <p>This class is a member of the |
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* <a href="{@docRoot}/../guide/collections/index.html"> |
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* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework"> |
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* Java Collections Framework</a>. |
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* |
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* @since 1.5 |
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* @version 1.8, 08/27/05 |
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* @author Josh Bloch |
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* @param <E> the type of elements held in this collection |
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* @author Josh Bloch, Doug Lea |
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* @param <E> the type of elements held in this queue |
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*/ |
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@SuppressWarnings("unchecked") |
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public class PriorityQueue<E> extends AbstractQueue<E> |
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implements java.io.Serializable { |
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|
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* heap and each descendant d of n, n <= d. The element with the |
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* lowest value is in queue[0], assuming the queue is nonempty. |
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*/ |
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private transient Object[] queue; |
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transient Object[] queue; // non-private to simplify nested class access |
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|
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/** |
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* The number of elements in the priority queue. |
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*/ |
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private int size = 0; |
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int size; |
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|
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/** |
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* The comparator, or null if priority queue uses elements' |
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* The number of times this priority queue has been |
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* <i>structurally modified</i>. See AbstractList for gory details. |
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*/ |
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private transient int modCount = 0; |
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transient int modCount; // non-private to simplify nested class access |
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|
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/** |
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* Creates a <tt>PriorityQueue</tt> with the default initial |
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* Creates a {@code PriorityQueue} with the default initial |
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* capacity (11) that orders its elements according to their |
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* {@linkplain Comparable natural ordering}. |
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*/ |
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} |
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|
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/** |
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* Creates a <tt>PriorityQueue</tt> with the specified initial |
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* Creates a {@code PriorityQueue} with the specified initial |
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* capacity that orders its elements according to their |
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* {@linkplain Comparable natural ordering}. |
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* |
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* @param initialCapacity the initial capacity for this priority queue |
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* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less |
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* than 1 |
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* @throws IllegalArgumentException if {@code initialCapacity} is less |
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* than 1 |
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*/ |
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public PriorityQueue(int initialCapacity) { |
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this(initialCapacity, null); |
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} |
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|
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/** |
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* Creates a <tt>PriorityQueue</tt> with the specified initial capacity |
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* Creates a {@code PriorityQueue} with the default initial capacity and |
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* whose elements are ordered according to the specified comparator. |
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* |
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* @param comparator the comparator that will be used to order this |
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* priority queue. If {@code null}, the {@linkplain Comparable |
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* natural ordering} of the elements will be used. |
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* @since 1.8 |
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*/ |
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public PriorityQueue(Comparator<? super E> comparator) { |
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this(DEFAULT_INITIAL_CAPACITY, comparator); |
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} |
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|
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/** |
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* Creates a {@code PriorityQueue} with the specified initial capacity |
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* that orders its elements according to the specified comparator. |
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* |
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* @param initialCapacity the initial capacity for this priority queue |
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* @param comparator the comparator that will be used to order |
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* this priority queue. If <tt>null</tt>, the <i>natural |
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* ordering</i> of the elements will be used. |
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* @throws IllegalArgumentException if <tt>initialCapacity</tt> is |
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* @param comparator the comparator that will be used to order this |
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* priority queue. If {@code null}, the {@linkplain Comparable |
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* natural ordering} of the elements will be used. |
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* @throws IllegalArgumentException if {@code initialCapacity} is |
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* less than 1 |
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*/ |
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public PriorityQueue(int initialCapacity, |
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} |
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|
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/** |
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* Creates a <tt>PriorityQueue</tt> containing the elements in the |
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* specified collection. If the specified collection is an |
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* instance of a {@link java.util.SortedSet} or is another |
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* <tt>PriorityQueue</tt>, the priority queue will be ordered |
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* according to the same ordering. Otherwise, this priority queue |
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* will be ordered according to the natural ordering of its elements. |
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* Creates a {@code PriorityQueue} containing the elements in the |
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* specified collection. If the specified collection is an instance of |
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* a {@link SortedSet} or is another {@code PriorityQueue}, this |
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* priority queue will be ordered according to the same ordering. |
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* Otherwise, this priority queue will be ordered according to the |
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* {@linkplain Comparable natural ordering} of its elements. |
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* |
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* @param c the collection whose elements are to be placed |
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* into this priority queue |
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* of its elements are null |
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*/ |
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public PriorityQueue(Collection<? extends E> c) { |
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initFromCollection(c); |
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if (c instanceof SortedSet) |
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comparator = (Comparator<? super E>) |
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((SortedSet<? extends E>)c).comparator(); |
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else if (c instanceof PriorityQueue) |
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comparator = (Comparator<? super E>) |
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((PriorityQueue<? extends E>)c).comparator(); |
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if (c instanceof SortedSet<?>) { |
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SortedSet<? extends E> ss = (SortedSet<? extends E>) c; |
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this.comparator = (Comparator<? super E>) ss.comparator(); |
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initElementsFromCollection(ss); |
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} |
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else if (c instanceof PriorityQueue<?>) { |
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PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c; |
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this.comparator = (Comparator<? super E>) pq.comparator(); |
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initFromPriorityQueue(pq); |
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} |
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else { |
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comparator = null; |
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heapify(); |
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this.comparator = null; |
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initFromCollection(c); |
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} |
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} |
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|
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/** |
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* Creates a <tt>PriorityQueue</tt> containing the elements in the |
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* Creates a {@code PriorityQueue} containing the elements in the |
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* specified priority queue. This priority queue will be |
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* ordered according to the same ordering as the given priority |
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* queue. |
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* |
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* @param c the priority queue whose elements are to be placed |
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* into this priority queue |
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* @throws ClassCastException if elements of <tt>c</tt> cannot be |
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* compared to one another according to <tt>c</tt>'s |
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* @throws ClassCastException if elements of {@code c} cannot be |
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* compared to one another according to {@code c}'s |
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* ordering |
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* @throws NullPointerException if the specified priority queue or any |
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* of its elements are null |
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*/ |
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public PriorityQueue(PriorityQueue<? extends E> c) { |
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comparator = (Comparator<? super E>)c.comparator(); |
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initFromCollection(c); |
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this.comparator = (Comparator<? super E>) c.comparator(); |
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initFromPriorityQueue(c); |
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} |
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|
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/** |
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< |
* Creates a <tt>PriorityQueue</tt> containing the elements in the |
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< |
* specified sorted set. This priority queue will be ordered |
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> |
* Creates a {@code PriorityQueue} containing the elements in the |
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> |
* specified sorted set. This priority queue will be ordered |
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* according to the same ordering as the given sorted set. |
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* |
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* @param c the sorted set whose elements are to be placed |
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< |
* into this priority queue. |
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> |
* into this priority queue |
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* @throws ClassCastException if elements of the specified sorted |
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* set cannot be compared to one another according to the |
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* sorted set's ordering |
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* of its elements are null |
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*/ |
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public PriorityQueue(SortedSet<? extends E> c) { |
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< |
comparator = (Comparator<? super E>)c.comparator(); |
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< |
initFromCollection(c); |
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> |
this.comparator = (Comparator<? super E>) c.comparator(); |
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> |
initElementsFromCollection(c); |
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> |
} |
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> |
|
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> |
/** Ensures that queue[0] exists, helping peek() and poll(). */ |
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> |
private static Object[] ensureNonEmpty(Object[] es) { |
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> |
return (es.length > 0) ? es : new Object[1]; |
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> |
} |
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> |
|
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> |
private void initFromPriorityQueue(PriorityQueue<? extends E> c) { |
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> |
if (c.getClass() == PriorityQueue.class) { |
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> |
this.queue = ensureNonEmpty(c.toArray()); |
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> |
this.size = c.size(); |
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> |
} else { |
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> |
initFromCollection(c); |
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> |
} |
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> |
} |
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> |
|
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> |
private void initElementsFromCollection(Collection<? extends E> c) { |
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> |
Object[] es = c.toArray(); |
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> |
int len = es.length; |
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> |
// If c.toArray incorrectly doesn't return Object[], copy it. |
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> |
if (es.getClass() != Object[].class) |
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> |
es = Arrays.copyOf(es, len, Object[].class); |
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> |
if (len == 1 || this.comparator != null) |
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> |
for (Object e : es) |
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> |
if (e == null) |
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> |
throw new NullPointerException(); |
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> |
this.queue = ensureNonEmpty(es); |
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> |
this.size = len; |
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} |
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|
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/** |
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< |
* Initialize queue array with elements from the given Collection. |
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> |
* Initializes queue array with elements from the given Collection. |
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> |
* |
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* @param c the collection |
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*/ |
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private void initFromCollection(Collection<? extends E> c) { |
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< |
Object[] a = c.toArray(); |
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< |
// If c.toArray incorrectly doesn't return Object[], copy it. |
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< |
if (a.getClass() != Object[].class) |
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< |
a = Arrays.copyOf(a, a.length, Object[].class); |
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< |
queue = a; |
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< |
size = a.length; |
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> |
initElementsFromCollection(c); |
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> |
heapify(); |
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} |
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|
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|
/** |
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+ |
* The maximum size of array to allocate. |
| 285 |
+ |
* Some VMs reserve some header words in an array. |
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+ |
* Attempts to allocate larger arrays may result in |
| 287 |
+ |
* OutOfMemoryError: Requested array size exceeds VM limit |
| 288 |
+ |
*/ |
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+ |
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; |
| 290 |
+ |
|
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+ |
/** |
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* Increases the capacity of the array. |
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* |
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|
* @param minCapacity the desired minimum capacity |
| 295 |
|
*/ |
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|
private void grow(int minCapacity) { |
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< |
if (minCapacity < 0) // overflow |
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< |
throw new OutOfMemoryError(); |
| 228 |
< |
int oldCapacity = queue.length; |
| 297 |
> |
int oldCapacity = queue.length; |
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|
// Double size if small; else grow by 50% |
| 299 |
< |
int newCapacity = ((oldCapacity < 64)? |
| 300 |
< |
((oldCapacity + 1) * 2): |
| 301 |
< |
((oldCapacity * 3) / 2)); |
| 302 |
< |
if (newCapacity < minCapacity) |
| 303 |
< |
newCapacity = minCapacity; |
| 299 |
> |
int newCapacity = oldCapacity + ((oldCapacity < 64) ? |
| 300 |
> |
(oldCapacity + 2) : |
| 301 |
> |
(oldCapacity >> 1)); |
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> |
// 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 |
|
* Inserts the specified element into this priority queue. |
| 318 |
|
* |
| 319 |
< |
* @return <tt>true</tt> (as specified by {@link Collection#add}) |
| 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 |
| 329 |
|
/** |
| 330 |
|
* Inserts the specified element into this priority queue. |
| 331 |
|
* |
| 332 |
< |
* @return <tt>true</tt> (as specified by {@link Queue#offer}) |
| 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 |
| 342 |
|
int i = size; |
| 343 |
|
if (i >= queue.length) |
| 344 |
|
grow(i + 1); |
| 345 |
+ |
siftUp(i, e); |
| 346 |
|
size = i + 1; |
| 268 |
– |
if (i == 0) |
| 269 |
– |
queue[0] = e; |
| 270 |
– |
else |
| 271 |
– |
siftUp(i, e); |
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|
return true; |
| 348 |
|
} |
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|
|
| 350 |
|
public E peek() { |
| 276 |
– |
if (size == 0) |
| 277 |
– |
return null; |
| 351 |
|
return (E) queue[0]; |
| 352 |
|
} |
| 353 |
|
|
| 354 |
|
private int indexOf(Object o) { |
| 355 |
< |
if (o != null) { |
| 356 |
< |
for (int i = 0; i < size; i++) |
| 357 |
< |
if (o.equals(queue[i])) |
| 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; |
| 363 |
|
|
| 364 |
|
/** |
| 365 |
|
* Removes a single instance of the specified element from this queue, |
| 366 |
< |
* if it is present. More formally, removes an element <tt>e</tt> such |
| 367 |
< |
* that <tt>o.equals(e)</tt>, if this queue contains one or more such |
| 368 |
< |
* elements. Returns true if this queue contained the specified element |
| 369 |
< |
* (or equivalently, if this queue changed as a result of the call). |
| 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 <tt>true</tt> if this queue changed as a result of the call |
| 373 |
> |
* @return {@code true} if this queue changed as a result of the call |
| 374 |
|
*/ |
| 375 |
|
public boolean remove(Object o) { |
| 376 |
< |
int i = indexOf(o); |
| 377 |
< |
if (i == -1) |
| 378 |
< |
return false; |
| 379 |
< |
else { |
| 380 |
< |
removeAt(i); |
| 381 |
< |
return true; |
| 382 |
< |
} |
| 376 |
> |
int i = indexOf(o); |
| 377 |
> |
if (i == -1) |
| 378 |
> |
return false; |
| 379 |
> |
else { |
| 380 |
> |
removeAt(i); |
| 381 |
> |
return true; |
| 382 |
> |
} |
| 383 |
|
} |
| 384 |
|
|
| 385 |
|
/** |
| 386 |
< |
* Version of remove using reference equality, not equals. |
| 312 |
< |
* Needed by iterator.remove |
| 386 |
> |
* Identity-based version for use in Itr.remove. |
| 387 |
|
* |
| 388 |
|
* @param o element to be removed from this queue, if present |
| 315 |
– |
* @return <tt>true</tt> if removed. |
| 389 |
|
*/ |
| 390 |
< |
boolean removeEq(Object o) { |
| 391 |
< |
for (int i = 0; i < size; i++) { |
| 392 |
< |
if (o == queue[i]) { |
| 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 |
< |
return true; |
| 395 |
> |
break; |
| 396 |
|
} |
| 397 |
|
} |
| 324 |
– |
return false; |
| 398 |
|
} |
| 399 |
|
|
| 400 |
|
/** |
| 401 |
< |
* Returns <tt>true</tt> if this queue contains the specified element. |
| 402 |
< |
* More formally, returns <tt>true</tt> if and only if this queue contains |
| 403 |
< |
* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>. |
| 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 <tt>true</tt> if this queue contains the specified element |
| 406 |
> |
* @return {@code true} if this queue contains the specified element |
| 407 |
|
*/ |
| 408 |
|
public boolean contains(Object o) { |
| 409 |
< |
return indexOf(o) != -1; |
| 409 |
> |
return indexOf(o) >= 0; |
| 410 |
|
} |
| 411 |
|
|
| 412 |
|
/** |
| 413 |
< |
* Returns an array containing all of the elements in this queue, |
| 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 list. (In other words, this method must allocate |
| 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 |
< |
* @return an array containing all of the elements in this queue. |
| 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. |
| 431 |
< |
* The elements are in no particular order. The runtime type of |
| 432 |
< |
* the returned array is that of the specified array. If the queue |
| 433 |
< |
* fits in the specified array, it is returned therein. |
| 434 |
< |
* Otherwise, a new array is allocated with the runtime type of |
| 435 |
< |
* the specified array and the size of this queue. |
| 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 |
< |
* <tt>null</tt>. (This is useful in determining the length of the |
| 441 |
< |
* queue <i>only</i> if the caller knows that the queue does not contain |
| 442 |
< |
* any null elements.) |
| 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 the elements of the queue |
| 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); |
| 470 |
> |
System.arraycopy(queue, 0, a, 0, size); |
| 471 |
|
if (a.length > size) |
| 472 |
|
a[size] = null; |
| 473 |
|
return a; |
| 488 |
|
* Index (into queue array) of element to be returned by |
| 489 |
|
* subsequent call to next. |
| 490 |
|
*/ |
| 491 |
< |
private int cursor = 0; |
| 491 |
> |
private int cursor; |
| 492 |
|
|
| 493 |
|
/** |
| 494 |
|
* Index of element returned by most recent call to next, |
| 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 ArrayDeque<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 E lastRetElt = null; |
| 517 |
> |
private E lastRetElt; |
| 518 |
|
|
| 519 |
|
/** |
| 520 |
|
* The modCount value that the iterator believes that the backing |
| 521 |
< |
* List should have. If this expectation is violated, the iterator |
| 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 || |
| 530 |
|
(forgetMeNot != null && !forgetMeNot.isEmpty()); |
| 547 |
|
public void remove() { |
| 548 |
|
if (expectedModCount != modCount) |
| 549 |
|
throw new ConcurrentModificationException(); |
| 459 |
– |
if (lastRet == -1 && lastRetElt == null) |
| 460 |
– |
throw new IllegalStateException(); |
| 550 |
|
if (lastRet != -1) { |
| 551 |
|
E moved = PriorityQueue.this.removeAt(lastRet); |
| 552 |
|
lastRet = -1; |
| 554 |
|
cursor--; |
| 555 |
|
else { |
| 556 |
|
if (forgetMeNot == null) |
| 557 |
< |
forgetMeNot = new ArrayDeque<E>(); |
| 557 |
> |
forgetMeNot = new ArrayDeque<>(); |
| 558 |
|
forgetMeNot.add(moved); |
| 559 |
|
} |
| 560 |
< |
} else { |
| 560 |
> |
} else if (lastRetElt != null) { |
| 561 |
|
PriorityQueue.this.removeEq(lastRetElt); |
| 562 |
|
lastRetElt = null; |
| 563 |
+ |
} else { |
| 564 |
+ |
throw new IllegalStateException(); |
| 565 |
|
} |
| 566 |
|
expectedModCount = modCount; |
| 567 |
|
} |
| 477 |
– |
|
| 568 |
|
} |
| 569 |
|
|
| 570 |
|
public int size() { |
| 577 |
|
*/ |
| 578 |
|
public void clear() { |
| 579 |
|
modCount++; |
| 580 |
< |
for (int i = 0; i < size; i++) |
| 581 |
< |
queue[i] = null; |
| 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; |
| 589 |
< |
int s = --size; |
| 590 |
< |
modCount++; |
| 591 |
< |
E result = (E)queue[0]; |
| 592 |
< |
E x = (E)queue[s]; |
| 593 |
< |
queue[s] = null; |
| 594 |
< |
if (s != 0) |
| 595 |
< |
siftDown(0, x); |
| 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 |
|
|
| 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 traverseing elements. |
| 616 |
> |
* avoid missing traversing elements. |
| 617 |
|
*/ |
| 618 |
< |
private E removeAt(int i) { |
| 619 |
< |
assert i >= 0 && i < size; |
| 618 |
> |
E removeAt(int i) { |
| 619 |
> |
// assert i >= 0 && i < size; |
| 620 |
> |
final Object[] es = queue; |
| 621 |
|
modCount++; |
| 622 |
|
int s = --size; |
| 623 |
|
if (s == i) // removed last element |
| 624 |
< |
queue[i] = null; |
| 624 |
> |
es[i] = null; |
| 625 |
|
else { |
| 626 |
< |
E moved = (E) queue[s]; |
| 627 |
< |
queue[s] = null; |
| 626 |
> |
E moved = (E) es[s]; |
| 627 |
> |
es[s] = null; |
| 628 |
|
siftDown(i, moved); |
| 629 |
< |
if (queue[i] == moved) { |
| 629 |
> |
if (es[i] == moved) { |
| 630 |
|
siftUp(i, moved); |
| 631 |
< |
if (queue[i] != moved) |
| 631 |
> |
if (es[i] != moved) |
| 632 |
|
return moved; |
| 633 |
|
} |
| 634 |
|
} |
| 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 |
| 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 |
|
* |
| 649 |
|
*/ |
| 650 |
|
private void siftUp(int k, E x) { |
| 651 |
|
if (comparator != null) |
| 652 |
< |
siftUpUsingComparator(k, x); |
| 652 |
> |
siftUpUsingComparator(k, x, queue, comparator); |
| 653 |
|
else |
| 654 |
< |
siftUpComparable(k, x); |
| 654 |
> |
siftUpComparable(k, x, queue); |
| 655 |
|
} |
| 656 |
|
|
| 657 |
< |
private void siftUpComparable(int k, E x) { |
| 658 |
< |
Comparable<? super E> key = (Comparable<? super E>) x; |
| 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 = queue[parent]; |
| 662 |
< |
if (key.compareTo((E)e) >= 0) |
| 661 |
> |
Object e = es[parent]; |
| 662 |
> |
if (key.compareTo((T) e) >= 0) |
| 663 |
|
break; |
| 664 |
< |
queue[k] = e; |
| 664 |
> |
es[k] = e; |
| 665 |
|
k = parent; |
| 666 |
|
} |
| 667 |
< |
queue[k] = key; |
| 667 |
> |
es[k] = key; |
| 668 |
|
} |
| 669 |
|
|
| 670 |
< |
private void siftUpUsingComparator(int k, E x) { |
| 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 = queue[parent]; |
| 675 |
< |
if (comparator.compare(x, (E)e) >= 0) |
| 674 |
> |
Object e = es[parent]; |
| 675 |
> |
if (cmp.compare(x, (T) e) >= 0) |
| 676 |
|
break; |
| 677 |
< |
queue[k] = e; |
| 677 |
> |
es[k] = e; |
| 678 |
|
k = parent; |
| 679 |
|
} |
| 680 |
< |
queue[k] = x; |
| 680 |
> |
es[k] = x; |
| 681 |
|
} |
| 682 |
|
|
| 683 |
|
/** |
| 690 |
|
*/ |
| 691 |
|
private void siftDown(int k, E x) { |
| 692 |
|
if (comparator != null) |
| 693 |
< |
siftDownUsingComparator(k, x); |
| 693 |
> |
siftDownUsingComparator(k, x, queue, size, comparator); |
| 694 |
|
else |
| 695 |
< |
siftDownComparable(k, x); |
| 695 |
> |
siftDownComparable(k, x, queue, size); |
| 696 |
|
} |
| 697 |
|
|
| 698 |
< |
private void siftDownComparable(int k, E x) { |
| 699 |
< |
Comparable<? super E> key = (Comparable<? super E>)x; |
| 700 |
< |
int half = size >>> 1; // loop while a non-leaf |
| 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 = queue[child]; |
| 704 |
> |
Object c = es[child]; |
| 705 |
|
int right = child + 1; |
| 706 |
< |
if (right < size && |
| 707 |
< |
((Comparable<? super E>)c).compareTo((E)queue[right]) > 0) |
| 708 |
< |
c = queue[child = right]; |
| 709 |
< |
if (key.compareTo((E)c) <= 0) |
| 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 |
< |
queue[k] = c; |
| 711 |
> |
es[k] = c; |
| 712 |
|
k = child; |
| 713 |
|
} |
| 714 |
< |
queue[k] = key; |
| 714 |
> |
es[k] = key; |
| 715 |
|
} |
| 716 |
|
|
| 717 |
< |
private void siftDownUsingComparator(int k, E x) { |
| 718 |
< |
int half = size >>> 1; |
| 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 = queue[child]; |
| 723 |
> |
Object c = es[child]; |
| 724 |
|
int right = child + 1; |
| 725 |
< |
if (right < size && |
| 726 |
< |
comparator.compare((E)c, (E)queue[right]) > 0) |
| 727 |
< |
c = queue[child = right]; |
| 625 |
< |
if (comparator.compare(x, (E)c) <= 0) |
| 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 |
< |
queue[k] = c; |
| 729 |
> |
es[k] = c; |
| 730 |
|
k = child; |
| 731 |
|
} |
| 732 |
< |
queue[k] = x; |
| 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 >>> 1) - 1; i >= 0; i--) |
| 742 |
< |
siftDown(i, (E)queue[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 the elements in this |
| 754 |
< |
* queue, or <tt>null</tt> if this queue is sorted according to |
| 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 |
< |
* <tt>null</tt> if this queue is sorted according to the |
| 759 |
< |
* natural ordering of its elements. |
| 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 |
| 657 |
< |
* is, serialize it). |
| 766 |
> |
* Saves this queue to a stream (that is, serializes it). |
| 767 |
|
* |
| 659 |
– |
* @serialData The length of the array backing the instance is |
| 660 |
– |
* emitted (int), followed by all of its elements (each an |
| 661 |
– |
* <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 |
< |
// For compatibility with 1.5 version, must be at least 2. |
| 671 |
< |
s.writeInt(Math.max(2, 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=0; 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>PriorityQueue</tt> instance from a stream |
| 790 |
< |
* (that is, 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=0; 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 |
|
} |
