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1   /*
2    * $Header$
3    * $Revision: 1253 $
4    * $Date: 2006-11-09 08:39:19 -0800 (Thu, 09 Nov 2006) $
5    *
6    * ====================================================================
7    *
8    * Copyright 2000-2002 bob mcwhirter & James Strachan.
9    * All rights reserved.
10   *
11   * Redistribution and use in source and binary forms, with or without
12   * modification, are permitted provided that the following conditions are
13   * met:
14   * 
15   *   * Redistributions of source code must retain the above copyright
16   *     notice, this list of conditions and the following disclaimer.
17   * 
18   *   * Redistributions in binary form must reproduce the above copyright
19   *     notice, this list of conditions and the following disclaimer in the
20   *     documentation and/or other materials provided with the distribution.
21   * 
22   *   * Neither the name of the Jaxen Project nor the names of its
23   *     contributors may be used to endorse or promote products derived 
24   *     from this software without specific prior written permission.
25   * 
26   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
27   * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
29   * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
30   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
31   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
32   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
33   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
36   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37   *
38   * ====================================================================
39   * This software consists of voluntary contributions made by many 
40   * individuals on behalf of the Jaxen Project and was originally 
41   * created by bob mcwhirter <bob@werken.com> and 
42   * James Strachan <jstrachan@apache.org>.  For more information on the 
43   * Jaxen Project, please see <http://www.jaxen.org/>.
44   * 
45   * $Id: SingletonList.java 1253 2006-11-09 16:39:19Z elharo $
46   */
47  
48  
49  
50  package org.jaxen.util;
51  
52  import java.util.AbstractList;
53  
54  /**
55   * A utility class that implements singleton lists
56   * (to avoid dependency on JDK 1.3). Many operations 
57   * including <code>add()</code> and <code>remove()</code> throw
58   * UnsupportedOperationExceptions. 
59   * 
60   * @version 1.2b12
61   * @author Attila Szegedi
62   * 
63   */
64  public class SingletonList extends AbstractList {
65      
66      private final Object element;
67      
68      /**
69       * Creates a new singleton list. 
70       * 
71       * @param element the single member of the list
72       */
73      public SingletonList(Object element) {
74          this.element = element;
75      }
76      
77      /** 
78       * Returns 1.
79       * 
80       * @return 1
81       */
82      public int size() {
83          return 1;
84      }
85  
86      /**
87       * Returns the single element in the list.
88       * 
89       * @return the only element in the list
90       * 
91       * @throws IndexOutOfBoundsException if index is not 0
92       * 
93       */
94      public Object get(int index) {
95          if(index == 0) {
96              return element;
97          }
98          throw new IndexOutOfBoundsException(index + " != 0");
99      }
100     
101 }