1 /*
2 * $Header: /home/cvs/jakarta-commons/betwixt/src/java/org/apache/commons/betwixt/io/id/RandomIDGenerator.java,v 1.3 2002/08/14 18:50:21 rdonkin Exp $
3 * $Revision: 1.3 $
4 * $Date: 2002/08/14 18:50:21 $
5 *
6 * ====================================================================
7 *
8 * The Apache Software License, Version 1.1
9 *
10 * Copyright (c) 1999-2002 The Apache Software Foundation. All rights
11 * reserved.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 *
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 *
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in
22 * the documentation and/or other materials provided with the
23 * distribution.
24 *
25 * 3. The end-user documentation included with the redistribution, if
26 * any, must include the following acknowlegement:
27 * "This product includes software developed by the
28 * Apache Software Foundation (http://www.apache.org/)."
29 * Alternately, this acknowlegement may appear in the software itself,
30 * if and wherever such third-party acknowlegements normally appear.
31 *
32 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
33 * Foundation" must not be used to endorse or promote products derived
34 * from this software without prior written permission. For written
35 * permission, please contact apache@apache.org.
36 *
37 * 5. Products derived from this software may not be called "Apache"
38 * nor may "Apache" appear in their names without prior written
39 * permission of the Apache Group.
40 *
41 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
42 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
43 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
44 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
45 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
46 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
47 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
48 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
49 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
50 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
51 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * SUCH DAMAGE.
53 * ====================================================================
54 *
55 * This software consists of voluntary contributions made by many
56 * individuals on behalf of the Apache Software Foundation. For more
57 * information on the Apache Software Foundation, please see
58 * <http://www.apache.org/>;.
59 *
60 * $Id: RandomIDGenerator.java,v 1.3 2002/08/14 18:50:21 rdonkin Exp $
61 */
62 package org.apache.commons.betwixt.io.id;
63
64 import java.util.Random;
65
66 /*** <p>Generates <code>ID</code>'s at random.
67 * The random number source is <code>java.util.Random</code>.</p>
68 *
69 * <p>Random <code>ID</code>'s are very useful if you're inserting
70 * elements created by <code>Betwixt</code> into a stream with existing
71 * elements.
72 * Using random <code>ID</code>'s should reduce the danger of collision
73 * with existing element <code>ID</code>'s.</p>
74 *
75 * <p>This class can generate positive-only ids (the default)
76 * or it can generate a mix of negative and postive ones.
77 * This behaviour can be set by {@link #setPositiveIds}
78 * or by using the {@link #RandomIDGenerator(boolean onlyPositiveIds)}
79 * constructor.</p>
80 *
81 * @author <a href="mailto:rdonkin@apache.org">Robert Burrell Donkin</a>
82 * @version $Revision: 1.3 $
83 */
84 public final class RandomIDGenerator extends AbstractIDGenerator {
85
86 /*** Use simple java.util.Random as the source for our numbers */
87 private Random random = new Random();
88 /*** Should only positive id's be generated? */
89 private boolean onlyPositiveIds = true;
90
91 /***
92 * Constructor sets the <code>PositiveIds</code> property to <code>true</code>.
93 */
94 public RandomIDGenerator() {}
95
96 /***
97 * Constructor sets <code>PositiveIds</code> property.
98 *
99 * @param onlyPositiveIds set <code>PositiveIds</code> property to this value
100 */
101 public RandomIDGenerator(boolean onlyPositiveIds) {
102 setPositiveIds(onlyPositiveIds);
103 }
104
105 /***
106 * <p>Provide a random <code>ID</code><p>
107 *
108 * <p>If the <code>PositiveIds</code> property is true,
109 * then this method will recursively call itself if the random
110 * <code>ID</code> is less than zero.</p>
111 */
112 public String nextIdImpl() {
113 int next = random.nextInt();
114 if (onlyPositiveIds && next<0) {
115 // it's negative and we're ignoring them so get another
116 return nextIdImpl();
117 }
118 return Integer.toString(next);
119 }
120
121 /*** Get whether only positive <code>ID</code>'s should be generated */
122 public boolean getPositiveIds() {
123 return onlyPositiveIds;
124 }
125
126 /*** Set whether only positive <code>ID</code>'s should be generated */
127 public void setPositiveIds(boolean onlyPositiveIds) {
128 this.onlyPositiveIds = onlyPositiveIds;
129 }
130 }
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