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/* |
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* %W% %E% |
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* @(#)PriorityQueue.java 1.8 05/08/27 |
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* |
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* Copyright 2004 Sun Microsystems, Inc. All rights reserved. |
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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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*/ |
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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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* An unbounded priority {@linkplain Queue queue} based on a priority |
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* heap. This queue orders elements according to an order specified |
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* at construction time, which is specified either according to their |
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* <i>natural order</i> (see {@link Comparable}), or according to a |
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* {@link java.util.Comparator}, depending on which constructor is |
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* used. A priority queue does not permit <tt>null</tt> elements. |
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* A priority queue relying on natural ordering also does not |
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* permit insertion of non-comparable objects (doing so may result |
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* in <tt>ClassCastException</tt>). |
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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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* |
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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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* |
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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. |
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* The |
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* Iterator provided in method {@link #iterator()} is <em>not</em> |
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* guaranteed to traverse the elements of the PriorityQueue in any |
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* particular order. If you need ordered traversal, consider using |
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* <tt>Arrays.sort(pq.toArray())</tt>. |
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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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* 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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* |
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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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* structurally. Instead, use the thread-safe {@link |
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* java.util.concurrent.PriorityBlockingQueue} class. |
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* |
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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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* <a href="{@docRoot}/../guide/collections/index.html"> |
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* Java Collections Framework</a>. |
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* @since 1.5 |
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* @version %I%, %G% |
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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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*/ |
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private transient int modCount = 0; |
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/** |
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* Creates a <tt>PriorityQueue</tt> with the default initial capacity |
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* (11) that orders its elements according to their natural |
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* ordering (using <tt>Comparable</tt>). |
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* Creates a <tt>PriorityQueue</tt> 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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public PriorityQueue() { |
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this(DEFAULT_INITIAL_CAPACITY, null); |
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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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* that orders its elements according to their natural ordering |
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* (using <tt>Comparable</tt>). |
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* Creates a <tt>PriorityQueue</tt> 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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* @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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*/ |
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* Creates a <tt>PriorityQueue</tt> 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 used to order this priority queue. |
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* If <tt>null</tt> then the order depends on the elements' natural |
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* ordering. |
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* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less |
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* than 1 |
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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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* less than 1 |
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*/ |
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public PriorityQueue(int initialCapacity, |
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public PriorityQueue(int initialCapacity, |
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Comparator<? super E> comparator) { |
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if (initialCapacity < 1) |
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throw new IllegalArgumentException(); |
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} |
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|
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/** |
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* Initially fill elements of the queue array under the |
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* Initially fill elements of the queue array under the |
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* knowledge that it is sorted or is another PQ, in which |
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* case we can just place the elements in the order presented. |
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*/ |
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private void fillFromSorted(Collection<? extends E> c) { |
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for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) |
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queue[++size] = i.next(); |
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for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) { |
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int k = ++size; |
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if (k >= queue.length) |
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grow(k); |
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queue[k] = i.next(); |
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} |
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} |
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|
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/** |
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* invariant. |
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*/ |
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private void fillFromUnsorted(Collection<? extends E> c) { |
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for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) |
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queue[++size] = i.next(); |
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for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) { |
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int k = ++size; |
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if (k >= queue.length) |
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grow(k); |
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queue[k] = i.next(); |
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} |
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heapify(); |
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} |
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|
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* capacity of 110% of the size of the specified collection or 1 |
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* if the collection is empty. 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 sorted |
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* according to the same comparator, or according to its elements' |
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* natural order if the collection is sorted according to its |
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* elements' natural order. Otherwise, the priority queue is |
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* ordered according to its elements' natural order. |
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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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* |
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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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* @param c the collection whose elements are to be placed |
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* into this priority queue |
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* @throws ClassCastException if elements of the specified collection |
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* cannot be compared to one another according to the priority |
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* queue's ordering. |
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* @throws NullPointerException if <tt>c</tt> or any element within it |
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* is <tt>null</tt> |
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* queue's ordering |
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* @throws NullPointerException if the specified collection or any |
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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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initializeArray(c); |
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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. The priority queue has an initial |
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* capacity of 110% of the size of the specified collection or 1 |
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* if the collection is empty. This priority queue will be sorted |
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* according to the same comparator as the given collection, or |
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* according to its elements' natural order if the collection is |
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* sorted according to its elements' natural order. |
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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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* @throws ClassCastException if elements of the specified collection |
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* cannot be compared to one another according to the priority |
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* queue's ordering. |
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* @throws NullPointerException if <tt>c</tt> or any element within it |
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* is <tt>null</tt> |
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* specified priority queue. The priority queue has an initial |
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* capacity of 110% of the size of the specified priority queue or |
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* 1 if the priority queue is empty. 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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* 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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initializeArray(c); |
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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. The priority queue has an initial |
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< |
* capacity of 110% of the size of the specified collection or 1 |
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< |
* if the collection is empty. This priority queue will be sorted |
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< |
* according to the same comparator as the given collection, or |
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< |
* according to its elements' natural order if the collection is |
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< |
* sorted according to its elements' natural order. |
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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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< |
* @throws ClassCastException if elements of the specified collection |
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< |
* cannot be compared to one another according to the priority |
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< |
* queue's ordering. |
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< |
* @throws NullPointerException if <tt>c</tt> or any element within it |
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< |
* is <tt>null</tt> |
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> |
* specified sorted set. The priority queue has an initial |
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> |
* capacity of 110% of the size of the specified sorted set or 1 |
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> |
* if the sorted set is empty. 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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> |
* @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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> |
* @throws NullPointerException if the specified sorted set or any |
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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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initializeArray(c); |
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} |
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|
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/** |
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* Resize array, if necessary, to be able to hold given index |
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* Resize array, if necessary, to be able to hold given index. |
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*/ |
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private void grow(int index) { |
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int newlen = queue.length; |
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else |
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newlen <<= 2; |
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} |
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< |
Object[] newQueue = new Object[newlen]; |
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< |
System.arraycopy(queue, 0, newQueue, 0, queue.length); |
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< |
queue = newQueue; |
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> |
queue = Arrays.copyOf(queue, newlen); |
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} |
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– |
|
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|
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/** |
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* Inserts the specified element into this priority queue. |
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* |
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< |
* @return <tt>true</tt> |
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< |
* @throws ClassCastException if the specified element cannot be compared |
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< |
* with elements currently in the priority queue according |
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< |
* to the priority queue's ordering. |
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< |
* @throws NullPointerException if the specified element is <tt>null</tt>. |
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> |
* @return <tt>true</tt> (as specified by {@link Collection#add}) |
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> |
* @throws ClassCastException if the specified element cannot be |
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> |
* compared with elements currently in this priority queue |
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> |
* according to the priority queue's ordering |
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> |
* @throws NullPointerException if the specified element is null |
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*/ |
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< |
public boolean offer(E o) { |
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< |
if (o == null) |
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> |
public boolean add(E e) { |
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> |
return offer(e); |
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> |
} |
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> |
|
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> |
/** |
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> |
* Inserts the specified element into this priority queue. |
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> |
* |
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> |
* @return <tt>true</tt> (as specified by {@link Queue#offer}) |
| 298 |
> |
* @throws ClassCastException if the specified element cannot be |
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> |
* compared with elements currently in this priority queue |
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> |
* according to the priority queue's ordering |
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> |
* @throws NullPointerException if the specified element is null |
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> |
*/ |
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> |
public boolean offer(E e) { |
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> |
if (e == null) |
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throw new NullPointerException(); |
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modCount++; |
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++size; |
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|
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// Grow backing store if necessary |
| 310 |
< |
if (size >= queue.length) |
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> |
if (size >= queue.length) |
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grow(size); |
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|
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< |
queue[size] = o; |
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> |
queue[size] = e; |
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fixUp(size); |
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return true; |
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} |
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return (E) queue[1]; |
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} |
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|
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< |
// Collection Methods - the first two override to update docs |
| 324 |
> |
private int indexOf(Object o) { |
| 325 |
> |
if (o == null) |
| 326 |
> |
return -1; |
| 327 |
> |
for (int i = 1; i <= size; i++) |
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> |
if (o.equals(queue[i])) |
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> |
return i; |
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> |
return -1; |
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> |
} |
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> |
|
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> |
/** |
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> |
* Removes a single instance of the specified element from this queue, |
| 335 |
> |
* if it is present. More formally, removes an element <tt>e</tt> such |
| 336 |
> |
* that <tt>o.equals(e)</tt>, if this queue contains one or more such |
| 337 |
> |
* elements. Returns true if this queue contained the specified element |
| 338 |
> |
* (or equivalently, if this queue changed as a result of the call). |
| 339 |
> |
* |
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> |
* @param o element to be removed from this queue, if present |
| 341 |
> |
* @return <tt>true</tt> if this queue changed as a result of the call |
| 342 |
> |
*/ |
| 343 |
> |
public boolean remove(Object o) { |
| 344 |
> |
int i = indexOf(o); |
| 345 |
> |
if (i == -1) |
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> |
return false; |
| 347 |
> |
else { |
| 348 |
> |
removeAt(i); |
| 349 |
> |
return true; |
| 350 |
> |
} |
| 351 |
> |
} |
| 352 |
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|
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|
/** |
| 354 |
< |
* Adds the specified element to this queue. |
| 355 |
< |
* @return <tt>true</tt> (as per the general contract of |
| 356 |
< |
* <tt>Collection.add</tt>). |
| 354 |
> |
* Returns <tt>true</tt> if this queue contains the specified element. |
| 355 |
> |
* More formally, returns <tt>true</tt> if and only if this queue contains |
| 356 |
> |
* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>. |
| 357 |
|
* |
| 358 |
< |
* @throws NullPointerException if the specified element is <tt>null</tt>. |
| 359 |
< |
* @throws ClassCastException if the specified element cannot be compared |
| 323 |
< |
* with elements currently in the priority queue according |
| 324 |
< |
* to the priority queue's ordering. |
| 358 |
> |
* @param o object to be checked for containment in this queue |
| 359 |
> |
* @return <tt>true</tt> if this queue contains the specified element |
| 360 |
|
*/ |
| 361 |
< |
public boolean add(E o) { |
| 362 |
< |
return offer(o); |
| 361 |
> |
public boolean contains(Object o) { |
| 362 |
> |
return indexOf(o) != -1; |
| 363 |
|
} |
| 364 |
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|
| 365 |
|
/** |
| 366 |
< |
* Removes a single instance of the specified element from this |
| 367 |
< |
* queue, if it is present. |
| 366 |
> |
* Returns an array containing all of the elements in this queue, |
| 367 |
> |
* The elements are in no particular order. |
| 368 |
> |
* |
| 369 |
> |
* <p>The returned array will be "safe" in that no references to it are |
| 370 |
> |
* maintained by this list. (In other words, this method must allocate |
| 371 |
> |
* a new array). The caller is thus free to modify the returned array. |
| 372 |
> |
* |
| 373 |
> |
* @return an array containing all of the elements in this queue. |
| 374 |
|
*/ |
| 375 |
< |
public boolean remove(Object o) { |
| 376 |
< |
if (o == null) |
| 377 |
< |
return false; |
| 375 |
> |
public Object[] toArray() { |
| 376 |
> |
return Arrays.copyOfRange(queue, 1, size+1); |
| 377 |
> |
} |
| 378 |
|
|
| 379 |
< |
if (comparator == null) { |
| 380 |
< |
for (int i = 1; i <= size; i++) { |
| 381 |
< |
if (((Comparable<E>)queue[i]).compareTo((E)o) == 0) { |
| 382 |
< |
removeAt(i); |
| 383 |
< |
return true; |
| 384 |
< |
} |
| 385 |
< |
} |
| 386 |
< |
} else { |
| 387 |
< |
for (int i = 1; i <= size; i++) { |
| 388 |
< |
if (comparator.compare((E)queue[i], (E)o) == 0) { |
| 389 |
< |
removeAt(i); |
| 390 |
< |
return true; |
| 391 |
< |
} |
| 392 |
< |
} |
| 393 |
< |
} |
| 394 |
< |
return false; |
| 379 |
> |
/** |
| 380 |
> |
* Returns an array containing all of the elements in this queue. |
| 381 |
> |
* The elements are in no particular order. The runtime type of |
| 382 |
> |
* the returned array is that of the specified array. If the queue |
| 383 |
> |
* fits in the specified array, it is returned therein. |
| 384 |
> |
* Otherwise, a new array is allocated with the runtime type of |
| 385 |
> |
* the specified array and the size of this queue. |
| 386 |
> |
* |
| 387 |
> |
* <p>If the queue fits in the specified array with room to spare |
| 388 |
> |
* (i.e., the array has more elements than the queue), the element in |
| 389 |
> |
* the array immediately following the end of the collection is set to |
| 390 |
> |
* <tt>null</tt>. (This is useful in determining the length of the |
| 391 |
> |
* queue <i>only</i> if the caller knows that the queue does not contain |
| 392 |
> |
* any null elements.) |
| 393 |
> |
* |
| 394 |
> |
* @param a the array into which the elements of the queue are to |
| 395 |
> |
* be stored, if it is big enough; otherwise, a new array of the |
| 396 |
> |
* same runtime type is allocated for this purpose. |
| 397 |
> |
* @return an array containing the elements of the queue |
| 398 |
> |
* @throws ArrayStoreException if the runtime type of the specified array |
| 399 |
> |
* is not a supertype of the runtime type of every element in |
| 400 |
> |
* this queue |
| 401 |
> |
* @throws NullPointerException if the specified array is null |
| 402 |
> |
*/ |
| 403 |
> |
public <T> T[] toArray(T[] a) { |
| 404 |
> |
if (a.length < size) |
| 405 |
> |
// Make a new array of a's runtime type, but my contents: |
| 406 |
> |
return (T[]) Arrays.copyOfRange(queue, 1, size+1, a.getClass()); |
| 407 |
> |
System.arraycopy(queue, 1, a, 0, size); |
| 408 |
> |
if (a.length > size) |
| 409 |
> |
a[size] = null; |
| 410 |
> |
return a; |
| 411 |
|
} |
| 412 |
|
|
| 413 |
|
/** |
| 414 |
|
* Returns an iterator over the elements in this queue. The iterator |
| 415 |
|
* does not return the elements in any particular order. |
| 416 |
|
* |
| 417 |
< |
* @return an iterator over the elements in this queue. |
| 417 |
> |
* @return an iterator over the elements in this queue |
| 418 |
|
*/ |
| 419 |
|
public Iterator<E> iterator() { |
| 420 |
|
return new Itr(); |
| 477 |
|
else { |
| 478 |
|
int remaining = forgetMeNot.size(); |
| 479 |
|
result = forgetMeNot.remove(remaining - 1); |
| 480 |
< |
if (remaining == 1) |
| 480 |
> |
if (remaining == 1) |
| 481 |
|
forgetMeNot = null; |
| 482 |
|
lastRet = 0; |
| 483 |
|
lastRetElt = result; |
| 519 |
|
} |
| 520 |
|
|
| 521 |
|
/** |
| 522 |
< |
* Removes all elements from the priority queue. |
| 522 |
> |
* Removes all of the elements from this priority queue. |
| 523 |
|
* The queue will be empty after this call returns. |
| 524 |
|
*/ |
| 525 |
|
public void clear() { |
| 559 |
|
* previously at the end of the list and is now at some position between |
| 560 |
|
* 2 and i-1 inclusive. |
| 561 |
|
*/ |
| 562 |
< |
private E removeAt(int i) { |
| 562 |
> |
private E removeAt(int i) { |
| 563 |
|
assert i > 0 && i <= size; |
| 564 |
|
modCount++; |
| 565 |
|
|
| 590 |
|
if (comparator == null) { |
| 591 |
|
while (k > 1) { |
| 592 |
|
int j = k >> 1; |
| 593 |
< |
if (((Comparable<E>)queue[j]).compareTo((E)queue[k]) <= 0) |
| 593 |
> |
if (((Comparable<? super E>)queue[j]).compareTo((E)queue[k]) <= 0) |
| 594 |
|
break; |
| 595 |
|
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
| 596 |
|
k = j; |
| 619 |
|
int j; |
| 620 |
|
if (comparator == null) { |
| 621 |
|
while ((j = k << 1) <= size && (j > 0)) { |
| 622 |
< |
if (j<size && |
| 623 |
< |
((Comparable<E>)queue[j]).compareTo((E)queue[j+1]) > 0) |
| 622 |
> |
if (j<size && |
| 623 |
> |
((Comparable<? super E>)queue[j]).compareTo((E)queue[j+1]) > 0) |
| 624 |
|
j++; // j indexes smallest kid |
| 625 |
|
|
| 626 |
< |
if (((Comparable<E>)queue[k]).compareTo((E)queue[j]) <= 0) |
| 626 |
> |
if (((Comparable<? super E>)queue[k]).compareTo((E)queue[j]) <= 0) |
| 627 |
|
break; |
| 628 |
|
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
| 629 |
|
k = j; |
| 630 |
|
} |
| 631 |
|
} else { |
| 632 |
|
while ((j = k << 1) <= size && (j > 0)) { |
| 633 |
< |
if (j<size && |
| 633 |
> |
if (j<size && |
| 634 |
|
comparator.compare((E)queue[j], (E)queue[j+1]) > 0) |
| 635 |
|
j++; // j indexes smallest kid |
| 636 |
|
if (comparator.compare((E)queue[k], (E)queue[j]) <= 0) |
| 651 |
|
} |
| 652 |
|
|
| 653 |
|
/** |
| 654 |
< |
* Returns the comparator used to order this collection, or <tt>null</tt> |
| 655 |
< |
* if this collection is sorted according to its elements natural ordering |
| 656 |
< |
* (using <tt>Comparable</tt>). |
| 657 |
< |
* |
| 658 |
< |
* @return the comparator used to order this collection, or <tt>null</tt> |
| 659 |
< |
* if this collection is sorted according to its elements natural ordering. |
| 654 |
> |
* Returns the comparator used to order the elements in this |
| 655 |
> |
* queue, or <tt>null</tt> if this queue is sorted according to |
| 656 |
> |
* the {@linkplain Comparable natural ordering} of its elements. |
| 657 |
> |
* |
| 658 |
> |
* @return the comparator used to order this queue, or |
| 659 |
> |
* <tt>null</tt> if this queue is sorted according to the |
| 660 |
> |
* natural ordering of its elements. |
| 661 |
|
*/ |
| 662 |
|
public Comparator<? super E> comparator() { |
| 663 |
|
return comparator; |
| 686 |
|
} |
| 687 |
|
|
| 688 |
|
/** |
| 689 |
< |
* Reconstitute the <tt>ArrayList</tt> instance from a stream (that is, |
| 690 |
< |
* deserialize it). |
| 689 |
> |
* Reconstitute the <tt>PriorityQueue</tt> instance from a stream |
| 690 |
> |
* (that is, deserialize it). |
| 691 |
|
* @param s the stream |
| 692 |
|
*/ |
| 693 |
|
private void readObject(java.io.ObjectInputStream s) |
