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1   /***
2    * Redistribution  and use  in source  and binary  forms, with  or without
3    * modification, are permitted provided  that the following conditions are
4    * met :
5    *
6    * . Redistributions  of  source  code  must  retain  the  above copyright
7    *   notice, this list of conditions and the following disclaimer.
8    *
9    * . Redistributions in  binary form  must reproduce  the above  copyright
10   *   notice, this list of conditions  and the following disclaimer in  the
11   *   documentation and/or other materials provided with the distribution.
12   *
13   * . The name of the author may not be used to endorse or promote products
14   *   derived from this software without specific prior written permission.
15   *
16   * THIS SOFTWARE IS  PROVIDED BY THE  AUTHOR ``AS IS''  AND ANY EXPRESS  OR
17   * IMPLIED  WARRANTIES,  INCLUDING,  BUT   NOT  LIMITED  TO,  THE   IMPLIED
18   * WARRANTIES OF MERCHANTABILITY AND  FITNESS FOR A PARTICULAR  PURPOSE ARE
19   * DISCLAIMED.  IN NO  EVENT SHALL  THE AUTHOR  BE LIABLE  FOR ANY  DIRECT,
20   * INDIRECT,  INCIDENTAL,  SPECIAL,  EXEMPLARY,  OR  CONSEQUENTIAL  DAMAGES
21   * (INCLUDING,  BUT  NOT LIMITED  TO,  PROCUREMENT OF  SUBSTITUTE  GOODS OR
22   * SERVICES;  LOSS  OF USE,  DATA,  OR PROFITS;  OR  BUSINESS INTERRUPTION)
23   * HOWEVER CAUSED  AND ON  ANY THEORY  OF LIABILITY,  WHETHER IN  CONTRACT,
24   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
25   * ANY  WAY  OUT OF  THE  USE OF  THIS  SOFTWARE, EVEN  IF  ADVISED OF  THE
26   * POSSIBILITY OF SUCH DAMAGE.
27   *
28   * $Id: RandomIterator.java,v 1.3 2005/08/26 18:09:36 mat007 Exp $
29   */
30  
31  package jtge.util.random;
32  
33  import java.util.Iterator;
34  import java.util.Vector;
35  
36  /***
37   * Wraps an iterator to provide randomization of its elements.
38   *
39   * @author Mathieu Champlon
40   * @version $Revision: 1.3 $ $Date: 2005/08/26 18:09:36 $
41   */
42  public class RandomIterator implements Iterator
43  {
44      /***
45       * The randomized iterator.
46       */
47      private final Iterator iterator;
48  
49      /***
50       * Create a random iterator over a list.
51       *
52       * @param random the random number generator
53       * @param iterator the data to randomize
54       */
55      public RandomIterator( final IRandom random, final Iterator iterator )
56      {
57          if( random == null )
58              throw new IllegalArgumentException( "argument 'random' is null" );
59          final Vector vector = new Vector();
60          if( iterator != null )
61              while( iterator.hasNext() )
62                  vector.insertElementAt( iterator.next(), random.nextInt( vector.size() + 1 ) );
63          this.iterator = vector.iterator();
64      }
65  
66      /***
67       * {@inheritDoc}
68       */
69      public final void remove()
70      {
71          throw new UnsupportedOperationException();
72      }
73  
74      /***
75       * {@inheritDoc}
76       */
77      public final boolean hasNext()
78      {
79          return iterator.hasNext();
80      }
81  
82      /***
83       * {@inheritDoc}
84       */
85      public final Object next()
86      {
87          return iterator.next();
88      }
89  }