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 *  (the "License"); you may not use this file except in compliance with
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package org.apache.commons.collections;

Defines a collection for priority queues, which can insert, peek and pop.

This interface is now replaced by the Buffer interface.
Author:
Peter Donald
Deprecated:
Replaced by the Buffer interface and implementations in buffer subpackage.
 Due to be removed in v4.0.
Since:
Commons Collections 1.0
Version:
$Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $/**
 * Defines a collection for priority queues, which can insert, peek and pop.
 * <p>
 * This interface is now replaced by the <code>Buffer</code> interface.
 *
 * @deprecated Replaced by the Buffer interface and implementations in buffer subpackage.
 *  Due to be removed in v4.0.
 * @since Commons Collections 1.0
 * @version $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
 * 
 * @author Peter Donald
 */
public interface PriorityQueue {
    
    
Clear all elements from queue.
/**
     * Clear all elements from queue.
     */
    void clear();

    
Test if queue is empty.
Returns:
true if queue is empty else false./**
     * Test if queue is empty.
     *
     * @return true if queue is empty else false.
     */
    boolean isEmpty();

    
Insert an element into queue.
Params:
element – the element to be inserted
Throws:
ClassCastException – if the specified element's
type prevents it from being compared to other items in the queue to
determine its relative priority./**
     * Insert an element into queue.
     *
     * @param element the element to be inserted
     *
     * @throws ClassCastException if the specified <code>element</code>'s
     * type prevents it from being compared to other items in the queue to
     * determine its relative priority.  
     */
    void insert(Object element);

    
Return element on top of heap but don't remove it.
Throws:
NoSuchElementException – if isEmpty() == true
Returns:
the element at top of heap/**
     * Return element on top of heap but don't remove it.
     *
     * @return the element at top of heap
     * @throws java.util.NoSuchElementException if <code>isEmpty() == true</code>
     */
    Object peek();

    
Return element on top of heap and remove it.
Throws:
NoSuchElementException – if isEmpty() == true
Returns:
the element at top of heap/**
     * Return element on top of heap and remove it.
     *
     * @return the element at top of heap
     * @throws java.util.NoSuchElementException if <code>isEmpty() == true</code>
     */
    Object pop();
    
}