| Randomizer.java |
1 /**
2 * Copyright (c) 2000-2009 Liferay, Inc. All rights reserved.
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a copy
5 * of this software and associated documentation files (the "Software"), to deal
6 * in the Software without restriction, including without limitation the rights
7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8 * copies of the Software, and to permit persons to whom the Software is
9 * furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice shall be included in
12 * all copies or substantial portions of the Software.
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
17 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
20 * SOFTWARE.
21 */
22
23 package com.liferay.portal.kernel.util;
24
25 import java.util.Iterator;
26 import java.util.LinkedHashSet;
27 import java.util.List;
28 import java.util.Random;
29 import java.util.Set;
30
31 /**
32 * <a href="Randomizer.java.html"><b><i>View Source</i></b></a>
33 *
34 * @author Brian Wing Shun Chan
35 *
36 */
37 public class Randomizer extends Random {
38
39 public static Randomizer getInstance() {
40 return _instance;
41 }
42
43 public Randomizer() {
44 super();
45 }
46
47 public Randomizer(long seed) {
48 super(seed);
49 }
50
51 public int[] nextInt(int n, int size) {
52 if (size > n) {
53 size = n;
54 }
55
56 Set<Integer> set = new LinkedHashSet<Integer>();
57
58 for (int i = 0; i < size; i++) {
59 while (true) {
60 Integer value = new Integer(nextInt(n));
61
62 if (!set.contains(value)) {
63 set.add(value);
64
65 break;
66 }
67 }
68 }
69
70 int[] array = new int[set.size()];
71
72 Iterator<Integer> itr = set.iterator();
73
74 for (int i = 0; i < array.length; i++) {
75 array[i] = itr.next().intValue();
76 }
77
78 return array;
79 }
80
81 public void randomize(char array[]) {
82 int length = array.length;
83
84 for (int i = 0; i < length - 1; i++) {
85 int x = nextInt(length);
86 char y = array[i];
87
88 array[i] = array[i + x];
89 array[i + x] = y;
90
91 length--;
92 }
93 }
94
95 public void randomize(int array[]) {
96 int length = array.length;
97
98 for (int i = 0; i < length - 1; i++) {
99 int x = nextInt(length);
100 int y = array[i];
101
102 array[i] = array[i + x];
103 array[i + x] = y;
104
105 length--;
106 }
107 }
108
109 public void randomize(List<Object> list) {
110 int size = list.size();
111
112 for (int i = 0; i <= size; i++) {
113 Object obj = list.get(i);
114
115 int j = nextInt(size);
116
117 list.set(i, list.get(i + j));
118 list.set(i + j, obj);
119
120 size--;
121 }
122 }
123
124 public void randomize(Object array[]) {
125 int length = array.length;
126
127 for (int i = 0; i < length - 1; i++) {
128 int x = nextInt(length);
129 Object y = array[i];
130
131 array[i] = array[i + x];
132 array[i + x] = y;
133
134 length--;
135 }
136 }
137
138 public String randomize(String s) {
139 if (s == null) {
140 return null;
141 }
142
143 char[] array = s.toCharArray();
144
145 randomize(array);
146
147 return new String(array);
148 }
149
150 private static Randomizer _instance = new Randomizer();
151
152 }