/*
* Copyright 2001-2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.collections;
/**
* 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: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $
*
* @author Peter Donald
*/
public interface PriorityQueue {
/**
* Clear all elements from queue.
*/
void clear();
/**
* Test if queue is empty.
*
* @return true if queue is empty else false.
*/
boolean isEmpty();
/**
* 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.
*
* @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.
*
* @return the element at top of heap
* @throws java.util.NoSuchElementException if <code>isEmpty() == true</code>
*/
Object pop();
}