1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.math.random;
18
19 import java.util.Random;
20
21 /**
22 * Extension of <code>java.util.Random</code> wrapping a
23 * {@link RandomGenerator}.
24 *
25 * @since 1.1
26 * @version $Revision: 628614 $ $Date: 2008-02-17 21:47:53 -0700 (Sun, 17 Feb 2008) $
27 */
28 public class RandomAdaptor extends Random implements RandomGenerator {
29
30 /** Serializable version identifier */
31 private static final long serialVersionUID = 2570805822599485047L;
32
33 /** Wrapped randomGenerator instance */
34 private RandomGenerator randomGenerator = null;
35
36 /**
37 * Prevent instantiation without a generator argument
38 */
39 private RandomAdaptor() { }
40
41 /**
42 * Construct a RandomAdaptor wrapping the supplied RandomGenerator.
43 *
44 * @param randomGenerator the wrapped generator
45 */
46 public RandomAdaptor(RandomGenerator randomGenerator) {
47 this.randomGenerator = randomGenerator;
48 }
49
50 /**
51 * Factory method to create a <code>Random</code> using the supplied
52 * <code>RandomGenerator</code>.
53 *
54 * @param randomGenerator wrapped RandomGenerator instance
55 * @return a Random instance wrapping the RandomGenerator
56 */
57 public static Random createAdaptor(RandomGenerator randomGenerator) {
58 return new RandomAdaptor(randomGenerator);
59 }
60
61 /**
62 * Returns the next pseudorandom, uniformly distributed
63 * <code>boolean</code> value from this random number generator's
64 * sequence.
65 *
66 * @return the next pseudorandom, uniformly distributed
67 * <code>boolean</code> value from this random number generator's
68 * sequence
69 */
70 public boolean nextBoolean() {
71 return randomGenerator.nextBoolean();
72 }
73
74 /**
75 * Generates random bytes and places them into a user-supplied
76 * byte array. The number of random bytes produced is equal to
77 * the length of the byte array.
78 *
79 * @param bytes the non-null byte array in which to put the
80 * random bytes
81 */
82 public void nextBytes(byte[] bytes) {
83 randomGenerator.nextBytes(bytes);
84 }
85
86 /**
87 * Returns the next pseudorandom, uniformly distributed
88 * <code>double</code> value between <code>0.0</code> and
89 * <code>1.0</code> from this random number generator's sequence.
90 *
91 * @return the next pseudorandom, uniformly distributed
92 * <code>double</code> value between <code>0.0</code> and
93 * <code>1.0</code> from this random number generator's sequence
94 */
95 public double nextDouble() {
96 return randomGenerator.nextDouble();
97 }
98
99 /**
100 * Returns the next pseudorandom, uniformly distributed <code>float</code>
101 * value between <code>0.0</code> and <code>1.0</code> from this random
102 * number generator's sequence.
103 *
104 * @return the next pseudorandom, uniformly distributed <code>float</code>
105 * value between <code>0.0</code> and <code>1.0</code> from this
106 * random number generator's sequence
107 */
108 public float nextFloat() {
109 return randomGenerator.nextFloat();
110 }
111
112 /**
113 * Returns the next pseudorandom, Gaussian ("normally") distributed
114 * <code>double</code> value with mean <code>0.0</code> and standard
115 * deviation <code>1.0</code> from this random number generator's sequence.
116 *
117 * @return the next pseudorandom, Gaussian ("normally") distributed
118 * <code>double</code> value with mean <code>0.0</code> and
119 * standard deviation <code>1.0</code> from this random number
120 * generator's sequence
121 */
122 public double nextGaussian() {
123 return randomGenerator.nextGaussian();
124 }
125
126 /**
127 * Returns the next pseudorandom, uniformly distributed <code>int</code>
128 * value from this random number generator's sequence.
129 * All 2<font size="-1"><sup>32</sup></font> possible <tt>int</tt> values
130 * should be produced with (approximately) equal probability.
131 *
132 * @return the next pseudorandom, uniformly distributed <code>int</code>
133 * value from this random number generator's sequence
134 */
135 public int nextInt() {
136 return randomGenerator.nextInt();
137 }
138
139 /**
140 * Returns a pseudorandom, uniformly distributed <tt>int</tt> value
141 * between 0 (inclusive) and the specified value (exclusive), drawn from
142 * this random number generator's sequence.
143 *
144 * @param n the bound on the random number to be returned. Must be
145 * positive.
146 * @return a pseudorandom, uniformly distributed <tt>int</tt>
147 * value between 0 (inclusive) and n (exclusive).
148 * @throws IllegalArgumentException if n is not positive.
149 */
150 public int nextInt(int n) {
151 return randomGenerator.nextInt(n);
152 }
153
154 /**
155 * Returns the next pseudorandom, uniformly distributed <code>long</code>
156 * value from this random number generator's sequence. All
157 * 2<font size="-1"><sup>64</sup></font> possible <tt>long</tt> values
158 * should be produced with (approximately) equal probability.
159 *
160 * @return the next pseudorandom, uniformly distributed <code>long</code>
161 *value from this random number generator's sequence
162 */
163 public long nextLong() {
164 return randomGenerator.nextLong();
165 }
166
167 /**
168 * Sets the seed of the underyling random number generator using a
169 * <code>long</code> seed. Sequences of values generated starting with the
170 * same seeds should be identical.
171 *
172 * @param seed the seed value
173 */
174 public void setSeed(long seed) {
175 if (randomGenerator != null) { // required to avoid NPE in constructor
176 randomGenerator.setSeed(seed);
177 }
178 }
179 }