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1 /**
2  * Redistribution and use of this software and associated documentation
3  * ("Software"), with or without modification, are permitted provided
4  * that the following conditions are met:
5  *
6  * 1. Redistributions of source code must retain copyright
7  * statements and notices. Redistributions must also contain a
8  * copy of this document.
9  *
10  * 2. Redistributions in binary form must reproduce the
11  * above copyright notice, this list of conditions and the
12  * following disclaimer in the documentation and/or other
13  * materials provided with the distribution.
14  *
15  * 3. The name "Exolab" must not be used to endorse or promote
16  * products derived from this Software without prior written
17  * permission of Exoffice Technologies. For written permission,
18  * please contact info@exolab.org.
19  *
20  * 4. Products derived from this Software may not be called "Exolab"
21  * nor may "Exolab" appear in their names without prior written
22  * permission of Exoffice Technologies. Exolab is a registered
23  * trademark of Exoffice Technologies.
24  *
25  * 5. Due credit should be given to the Exolab Project
26  * (http://www.exolab.org/).
27  *
28  * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
29  * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
30  * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
31  * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
32  * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
33  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
34  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
35  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
37  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
39  * OF THE POSSIBILITY OF SUCH DAMAGE.
40  *
41  * Copyright 1999 (C) Exoffice Technologies Inc. All Rights Reserved.
42  *
43  * $Id: ArrayStack.java 1096 2004-03-26 21:41:16Z dblevins $
44  */
45 package org.openejb.util;
46
47
48 import java.util.ArrayList JavaDoc;
49 import java.util.EmptyStackException JavaDoc;
50
51 /**
52  * Unsynchronized Stack.
53  */
54 public final class ArrayStack extends ArrayList JavaDoc implements Stack{
55
56
57     /**
58      * Sets the size of the stack and prunes entries from the top
59      * of the stack that exceed the stack's new size.
60      */
61     public void setSize(int newSize) {
62         if (newSize == 0) clear();
63         else {
64             for (int i = size() - 1; i >= newSize; i--) remove(i);
65         }
66     }
67
68     /**
69      * Adds the object to the top of the stack.
70      */
71     public Object JavaDoc push(Object JavaDoc item) {
72         add(item);
73         return item;
74     }
75
76     /**
77      * Removes the object at the top of this stack and returns that
78      * object as the value of this function.
79      *
80      * @return The object at the top of this stack.
81      * @exception EmptyStackException if this stack is empty.
82      */
83     public Object JavaDoc pop() {
84         Object JavaDoc obj;
85         obj = peek();
86
87         int len = size();
88         remove(len - 1);
89
90         return obj;
91     }
92
93     /**
94      * Looks at the object at the top of this stack without removing it
95      * from the stack.
96      *
97      * @return the object at the top of this stack.
98      * @exception EmptyStackException if this stack is empty.
99      */
100     public Object JavaDoc peek() {
101         int len = size();
102
103         if (len == 0) throw new EmptyStackException JavaDoc();
104
105         return get(len - 1);
106     }
107 }
108
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