PriorityQueue


1   /*
2    *  Copyright 2001-2004 The Apache Software Foundation
3    *
4    *  Licensed under the Apache License, Version 2.0 (the "License");
5    *  you may not use this file except in compliance with the License.
6    *  You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   *  Unless required by applicable law or agreed to in writing, software
11   *  distributed under the License is distributed on an "AS IS" BASIS,
12   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   *  See the License for the specific language governing permissions and
14   *  limitations under the License.
15   */
16  package org.apache.commons.collections;
17  
18  /**
19   * Defines a collection for priority queues, which can insert, peek and pop.
20   * <p>
21   * This interface is now replaced by the <code>Buffer</code> interface.
22   *
23   * @deprecated Replaced by the Buffer interface and implementations in buffer subpackage.
24   *  Due to be removed in v4.0.
25   * @since Commons Collections 1.0
26   * @version $Revision: 1.14 $ $Date: 2004/02/18 01:15:42 $
27   * 
28   * @author Peter Donald
29   */
30  public interface PriorityQueue {
31      
32      /**
33       * Clear all elements from queue.
34       */
35      void clear();
36  
37      /**
38       * Test if queue is empty.
39       *
40       * @return true if queue is empty else false.
41       */
42      boolean isEmpty();
43  
44      /**
45       * Insert an element into queue.
46       *
47       * @param element the element to be inserted
48       *
49       * @throws ClassCastException if the specified <code>element</code>'s
50       * type prevents it from being compared to other items in the queue to
51       * determine its relative priority.  
52       */
53      void insert(Object   element);
54  
55      /**
56       * Return element on top of heap but don't remove it.
57       *
58       * @return the element at top of heap
59       * @throws java.util.NoSuchElementException if <code>isEmpty() == true</code>
60       */
61      Object   peek();
62  
63      /**
64       * Return element on top of heap and remove it.
65       *
66       * @return the element at top of heap
67       * @throws java.util.NoSuchElementException if <code>isEmpty() == true</code>
68       */
69      Object   pop();
70      
71  }
72
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