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 */
17package org.apache.commons.math.random;
18
19
20/**
21 * Interface extracted from <code>java.util.Random</code>.  This interface is
22 * implemented by {@link AbstractRandomGenerator}.
23 *
24 * @since 1.1
25 * @version $Revision: 949750 $ $Date: 2010-05-31 16:06:04 +0200 (lun. 31 mai 2010) $
26 */
27public interface RandomGenerator {
28
29    /**
30     * Sets the seed of the underlying random number generator using an
31     * <code>int</code> seed.
32     * <p>Sequences of values generated starting with the same seeds
33     * should be identical.
34     * </p>
35     * @param seed the seed value
36     */
37    void setSeed(int seed);
38
39    /**
40     * Sets the seed of the underlying random number generator using an
41     * <code>int</code> array seed.
42     * <p>Sequences of values generated starting with the same seeds
43     * should be identical.
44     * </p>
45     * @param seed the seed value
46     */
47    void setSeed(int[] seed);
48
49    /**
50     * Sets the seed of the underlying random number generator using a
51     * <code>long</code> seed.
52     * <p>Sequences of values generated starting with the same seeds
53     * should be identical.
54     * </p>
55     * @param seed the seed value
56     */
57    void setSeed(long seed);
58
59    /**
60     * Generates random bytes and places them into a user-supplied
61     * byte array.  The number of random bytes produced is equal to
62     * the length of the byte array.
63     *
64     * @param bytes the non-null byte array in which to put the
65     * random bytes
66     */
67    void nextBytes(byte[] bytes);
68
69    /**
70     * Returns the next pseudorandom, uniformly distributed <code>int</code>
71     * value from this random number generator's sequence.
72     * All 2<font size="-1"><sup>32</sup></font> possible <tt>int</tt> values
73     * should be produced with  (approximately) equal probability.
74     *
75     * @return the next pseudorandom, uniformly distributed <code>int</code>
76     *  value from this random number generator's sequence
77     */
78    int nextInt();
79
80    /**
81     * Returns a pseudorandom, uniformly distributed <tt>int</tt> value
82     * between 0 (inclusive) and the specified value (exclusive), drawn from
83     * this random number generator's sequence.
84     *
85     * @param n the bound on the random number to be returned.  Must be
86     * positive.
87     * @return  a pseudorandom, uniformly distributed <tt>int</tt>
88     * value between 0 (inclusive) and n (exclusive).
89     * @throws IllegalArgumentException  if n is not positive.
90     */
91    int nextInt(int n);
92
93    /**
94     * Returns the next pseudorandom, uniformly distributed <code>long</code>
95     * value from this random number generator's sequence.  All
96     * 2<font size="-1"><sup>64</sup></font> possible <tt>long</tt> values
97     * should be produced with (approximately) equal probability.
98     *
99     * @return  the next pseudorandom, uniformly distributed <code>long</code>
100     *value from this random number generator's sequence
101     */
102    long nextLong();
103
104    /**
105     * Returns the next pseudorandom, uniformly distributed
106     * <code>boolean</code> value from this random number generator's
107     * sequence.
108     *
109     * @return  the next pseudorandom, uniformly distributed
110     * <code>boolean</code> value from this random number generator's
111     * sequence
112     */
113    boolean nextBoolean();
114
115    /**
116     * Returns the next pseudorandom, uniformly distributed <code>float</code>
117     * value between <code>0.0</code> and <code>1.0</code> from this random
118     * number generator's sequence.
119     *
120     * @return  the next pseudorandom, uniformly distributed <code>float</code>
121     * value between <code>0.0</code> and <code>1.0</code> from this
122     * random number generator's sequence
123     */
124    float nextFloat();
125
126    /**
127     * Returns the next pseudorandom, uniformly distributed
128     * <code>double</code> value between <code>0.0</code> and
129     * <code>1.0</code> from this random number generator's sequence.
130     *
131     * @return  the next pseudorandom, uniformly distributed
132     *  <code>double</code> value between <code>0.0</code> and
133     *  <code>1.0</code> from this random number generator's sequence
134     */
135    double nextDouble();
136
137    /**
138     * Returns the next pseudorandom, Gaussian ("normally") distributed
139     * <code>double</code> value with mean <code>0.0</code> and standard
140     * deviation <code>1.0</code> from this random number generator's sequence.
141     *
142     * @return  the next pseudorandom, Gaussian ("normally") distributed
143     * <code>double</code> value with mean <code>0.0</code> and
144     * standard deviation <code>1.0</code> from this random number
145     *  generator's sequence
146     */
147    double nextGaussian();
148}
149