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 * https://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
18 /*
19 * This is not the original file distributed by the Apache Software Foundation
20 * It has been modified by the Hipparchus project
21 */
22 package org.hipparchus.random;
23
24 import java.io.Serializable;
25 import java.util.Random;
26
27 import org.hipparchus.exception.LocalizedCoreFormats;
28 import org.hipparchus.exception.MathIllegalArgumentException;
29 import org.hipparchus.util.MathUtils;
30
31 /**
32 * A {@link RandomGenerator} adapter that delegates the random number
33 * generation to the standard {@link java.util.Random} class.
34 */
35 public class JDKRandomGenerator extends IntRandomGenerator implements Serializable {
36
37 /** Serializable version identifier. */
38 private static final long serialVersionUID = 20151227L;
39
40 /** JDK's RNG. */
41 private final Random delegate;
42
43 /**
44 * Creates an instance with an arbitrary seed.
45 */
46 public JDKRandomGenerator() {
47 delegate = new Random();
48 }
49
50 /**
51 * Creates an instance with the given seed.
52 *
53 * @param seed Initial seed.
54 */
55 public JDKRandomGenerator(long seed) {
56 delegate = new Random(seed);
57 }
58
59 /**
60 * Creates an instance that wraps the given {@link Random} instance.
61 *
62 * @param random JDK {@link Random} instance that will generate the
63 * the random data.
64 * @throws MathIllegalArgumentException if random is null
65 */
66 public JDKRandomGenerator(Random random) {
67 MathUtils.checkNotNull(random);
68 delegate = random;
69 }
70
71 /** {@inheritDoc} */
72 @Override
73 public void setSeed(int seed) {
74 delegate.setSeed(seed);
75 }
76
77 /** {@inheritDoc} */
78 @Override
79 public void setSeed(long seed) {
80 delegate.setSeed(seed);
81 }
82
83 /** {@inheritDoc} */
84 @Override
85 public void setSeed(int[] seed) {
86 delegate.setSeed(convertToLong(seed));
87 }
88
89 /** {@inheritDoc} */
90 @Override
91 public void nextBytes(byte[] bytes) {
92 delegate.nextBytes(bytes);
93 }
94
95 /** {@inheritDoc} */
96 @Override
97 public int nextInt() {
98 return delegate.nextInt();
99 }
100
101 /** {@inheritDoc} */
102 @Override
103 public long nextLong() {
104 return delegate.nextLong();
105 }
106
107 /** {@inheritDoc} */
108 @Override
109 public boolean nextBoolean() {
110 return delegate.nextBoolean();
111 }
112
113 /** {@inheritDoc} */
114 @Override
115 public float nextFloat() {
116 return delegate.nextFloat();
117 }
118
119 /** {@inheritDoc} */
120 @Override
121 public double nextDouble() {
122 return delegate.nextDouble();
123 }
124
125 /** {@inheritDoc} */
126 @Override
127 public double nextGaussian() {
128 return delegate.nextGaussian();
129 }
130
131 /** {@inheritDoc} */
132 @Override
133 public int nextInt(int n) {
134 try {
135 return delegate.nextInt(n);
136 } catch (IllegalArgumentException e) {
137 throw new MathIllegalArgumentException(e, LocalizedCoreFormats.NUMBER_TOO_SMALL_BOUND_EXCLUDED,
138 n, 0);
139 }
140 }
141
142 /**
143 * Converts seed from one representation to another.
144 *
145 * @param seed Original seed.
146 * @return the converted seed.
147 */
148 private static long convertToLong(int[] seed) {
149 // The following number is the largest prime that fits
150 // in 32 bits (i.e. 2^32 - 5).
151 final long prime = 4294967291l;
152
153 long combined = 0l;
154 for (int s : seed) {
155 combined = combined * prime + s;
156 }
157
158 return combined;
159 }
160
161 }