1 /*
2 * $Header$
3 * $Revision$
4 * $Date$
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 * $Id$
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 }