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    1   /*
    2    * Copyright 2005 The Apache Software Foundation.
    3    *
    4    * Licensed under the Apache License, Version 2.0 (the "License");
    5    * you may not use this file except in compliance with the License.
    6    * You may obtain a copy of the License at
    7    *
    8    *      http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  package org.apache.commons.math.random;
    17
    18  import java.util.Random;
    19
    20  /***
    21   * Extension of <code>java.util.Random</code> wrapping a
    22   * {@link RandomGenerator}.
    23   *
    24   * @since 1.1
    25   * @version $Revision:$ $Date$
    26   */
    27  public class RandomAdaptor extends Random implements RandomGenerator {
    28
    29      /*** Wrapped randomGenerator instance */
    30      private RandomGenerator randomGenerator = null;
    31
    32      /***
    33       * Prevent instantiation without a generator argument
    34       */
    35      private RandomAdaptor() { }
    36
    37      /***
    38       * Construct a RandomAdaptor wrapping the supplied RandomGenerator.
    39       *
    40       * @param randomGenerator  the wrapped generator
    41       */
    42      public RandomAdaptor(RandomGenerator randomGenerator) {
    43          this.randomGenerator = randomGenerator;
    44      }
    45
    46      /***
    47       * Factory method to create a <code>Random</code> using the supplied
    48       * <code>RandomGenerator</code>.
    49       *
    50       * @param randomGenerator  wrapped RandomGenerator instance
    51       * @return a Random instance wrapping the RandomGenerator
    52       */
    53      public static Random createAdaptor(RandomGenerator randomGenerator) {
    54          return new RandomAdaptor(randomGenerator);
    55      }
    56
    57      /***
    58       * Returns the next pseudorandom, uniformly distributed
    59       * <code>boolean</code> value from this random number generator's
    60       * sequence.
    61       *
    62       * @return  the next pseudorandom, uniformly distributed
    63       * <code>boolean</code> value from this random number generator's
    64       * sequence
    65       */
    66      public boolean nextBoolean() {
    67          return randomGenerator.nextBoolean();
    68      }
    69
    70       /***
    71       * Generates random bytes and places them into a user-supplied
    72       * byte array.  The number of random bytes produced is equal to
    73       * the length of the byte array.
    74       *
    75       * @param bytes the non-null byte array in which to put the
    76       * random bytes
    77       */
    78      public void nextBytes(byte[] bytes) {
    79          randomGenerator.nextBytes(bytes);
    80      }
    81
    82       /***
    83       * Returns the next pseudorandom, uniformly distributed
    84       * <code>double</code> value between <code>0.0</code> and
    85       * <code>1.0</code> from this random number generator's sequence.
    86       *
    87       * @return  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      public double nextDouble() {
    92          return randomGenerator.nextDouble();
    93      }
    94
    95      /***
    96       * Returns the next pseudorandom, uniformly distributed <code>float</code>
    97       * value between <code>0.0</code> and <code>1.0</code> from this random
    98       * number generator's sequence.
    99       *
    100      * @return  the next pseudorandom, uniformly distributed <code>float</code>
    101      * value between <code>0.0</code> and <code>1.0</code> from this
    102      * random number generator's sequence
    103      */
    104     public float nextFloat() {
    105         return randomGenerator.nextFloat();
    106     }
    107
    108     /***
    109      * Returns the next pseudorandom, Gaussian ("normally") distributed
    110      * <code>double</code> value with mean <code>0.0</code> and standard
    111      * deviation <code>1.0</code> from this random number generator's sequence.
    112      *
    113      * @return  the next pseudorandom, Gaussian ("normally") distributed
    114      * <code>double</code> value with mean <code>0.0</code> and
    115      * standard deviation <code>1.0</code> from this random number
    116      *  generator's sequence
    117      */
    118     public double nextGaussian() {
    119         return randomGenerator.nextGaussian();
    120     }
    121
    122      /***
    123      * Returns the next pseudorandom, uniformly distributed <code>int</code>
    124      * value from this random number generator's sequence.
    125      * All 2<font size="-1"><sup>32</sup></font> possible <tt>int</tt> values
    126      * should be produced with  (approximately) equal probability.
    127      *
    128      * @return the next pseudorandom, uniformly distributed <code>int</code>
    129      *  value from this random number generator's sequence
    130      */
    131     public int nextInt() {
    132         return randomGenerator.nextInt();
    133     }
    134
    135     /***
    136      * Returns a pseudorandom, uniformly distributed <tt>int</tt> value
    137      * between 0 (inclusive) and the specified value (exclusive), drawn from
    138      * this random number generator's sequence.
    139      *
    140      * @param n the bound on the random number to be returned.  Must be
    141      * positive.
    142      * @return  a pseudorandom, uniformly distributed <tt>int</tt>
    143      * value between 0 (inclusive) and n (exclusive).
    144      * @throws IllegalArgumentException  if n is not positive.
    145      */
    146     public int nextInt(int n) {
    147         return randomGenerator.nextInt(n);
    148     }
    149
    150     /***
    151      * Returns the next pseudorandom, uniformly distributed <code>long</code>
    152      * value from this random number generator's sequence.  All
    153      * 2<font size="-1"><sup>64</sup></font> possible <tt>long</tt> values
    154      * should be produced with (approximately) equal probability.
    155      *
    156      * @return  the next pseudorandom, uniformly distributed <code>long</code>
    157      *value from this random number generator's sequence
    158      */
    159     public long nextLong() {
    160         return randomGenerator.nextLong();
    161     }
    162
    163     /***
    164      * Sets the seed of the underyling random number generator using a
    165      * <code>long</code> seed.  Sequences of values generated starting with the
    166      * same seeds should be identical.
    167      *
    168      * @param seed the seed value
    169      */
    170     public void setSeed(long seed) {
    171         if (randomGenerator != null) {  // required to avoid NPE in constructor
    172             randomGenerator.setSeed(seed);
    173         }
    174     }
    175 }