Source code: net/jxta/impl/rendezvous/rpv/PeerViewRandomWithReplaceStrategy.java
1 /*
2 * Copyright (c) 2002 Sun Microsystems, Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in
13 * the documentation and/or other materials provided with the
14 * distribution.
15 *
16 * 3. The end-user documentation included with the redistribution,
17 * if any, must include the following acknowledgment:
18 * "This product includes software developed by the
19 * Sun Microsystems, Inc. for Project JXTA."
20 * Alternately, this acknowledgment may appear in the software itself,
21 * if and wherever such third-party acknowledgments normally appear.
22 *
23 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and
24 * "Project JXTA" must not be used to endorse or promote products
25 * derived from this software without prior written permission.
26 * For written permission, please contact Project JXTA at
27 * http://www.jxta.org.
28 *
29 * 5. Products derived from this software may not be called "JXTA",
30 * nor may "JXTA" appear in their name, without prior written
31 * permission of Sun.
32 *
33 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
34 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
36 * DISCLAIMED. IN NO EVENT SHALL SUN MICROSYSTEMS OR
37 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
38 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
39 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
40 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
41 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
42 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
43 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
44 * SUCH DAMAGE.
45 * ====================================================================
46 *
47 * This software consists of voluntary contributions made by many
48 * individuals on behalf of Project JXTA. For more
49 * information on Project JXTA, please see
50 * <http://www.jxta.org/>.
51 *
52 * This license is based on the BSD license adopted by the Apache
53 * Foundation.
54 *
55 * $Id: PeerViewRandomWithReplaceStrategy.java,v 1.6 2004/05/18 19:22:11 bondolo Exp $
56 */
57 package net.jxta.impl.rendezvous.rpv;
58
59
60 import java.util.Random;
61 import java.util.SortedSet;
62 import java.util.Iterator;
63
64
65 /**
66 * Random with replacement
67 **/
68 class PeerViewRandomWithReplaceStrategy implements PeerViewStrategy {
69
70 private static Random random = new Random();
71 private SortedSet set = null;
72
73 PeerViewRandomWithReplaceStrategy(SortedSet set) {
74 this.set = set;
75 }
76
77 /**
78 * {@inheritDoc}
79 **/
80 public void reset() {}
81
82 /**
83 * {@inheritDoc}
84 **/
85 public PeerViewElement next() {
86 synchronized (set) {
87 if (set.isEmpty()) {
88 return null;
89 }
90
91 int i = random.nextInt(set.size());
92
93 // return the ith element
94 int n = 0;
95 Iterator si = set.iterator();
96
97 while (n < i) {
98 si.next();
99 n++;
100 }
101
102 return (PeerViewElement) si.next();
103 }
104 }
105 }