View Javadoc

1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/util/SingleObjectIterator.java,v 1.8 2006/11/09 18:20:12 elharo Exp $
3    * $Revision: 1.8 $
4    * $Date: 2006/11/09 18:20:12 $
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: SingleObjectIterator.java,v 1.8 2006/11/09 18:20:12 elharo Exp $
46   */
47  
48  
49  package org.jaxen.util;
50  
51  import java.util.Iterator;
52  import java.util.NoSuchElementException;
53  
54  /***
55   * Simple utility class that wraps an iterator around one object.
56   * This is a little more efficent than creating a one-object list.
57   *
58   */
59  public class SingleObjectIterator implements Iterator
60  {
61      
62      private Object  object;
63      private boolean seen;
64  
65      /***
66       * Creates a new single object iterator.
67       * 
68       * @param object the object to iterate over
69       */
70      public SingleObjectIterator(Object object)
71      {
72          this.object = object;
73          this.seen   = false;
74      }
75  
76  
77      /***
78       * Returns true if this iterator's element has not yet been seen; false if it has.
79       * 
80       * @return true if this iterator has another element; false if it doesn't
81       * 
82       * @see java.util.Iterator#hasNext()
83       */
84      public boolean hasNext()
85      {
86          return ! this.seen;
87      }
88  
89      /***
90       * Returns the single element in this iterator if it has not yet
91       * been seen. 
92       * 
93       * @return the next element in this iterator
94       * 
95       * @throws NoSuchElementException if the element has already been seen
96       * 
97       * @see java.util.Iterator#next()
98       */
99      public Object next()
100     {
101         if ( hasNext() )
102         {
103             this.seen = true;
104             return this.object;
105         }
106 
107         throw new NoSuchElementException();
108     }
109 
110     /***
111      * This operation is not supported.
112      * 
113      * @throws UnsupportedOperationException always
114      */
115     public void remove()
116     {
117         throw new UnsupportedOperationException();
118     }
119     
120 }