01: /*
02: * Copyright 2001-2004 The Apache Software Foundation
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
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: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $
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: }
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