src/java/org/apache/commons/lang/math/RandomUtils.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.commons.lang.math;

import java.util.Random;

/**
 * <p><code>RandomUtils</code> is a wrapper that supports all possible 
 * {@link java.util.Random} methods via the {@link java.lang.Math#random()}
 * method and its system-wide <code>Random</code> object.
 * 
 * @author Gary D. Gregory
 * @since 2.0
 * @version $Id$
 */
public class RandomUtils {

    /**
     * An instance of {@link JVMRandom}.
     */
    public static final Random JVM_RANDOM = new JVMRandom();

// should be possible for JVM_RANDOM?
//    public static void nextBytes(byte[]) {
//    public synchronized double nextGaussian();
//    }

    /**
     * <p>Returns the next pseudorandom, uniformly distributed int value
     * from the Math.random() sequence.</p>
     *
     * @return the random int
     */
    public static int nextInt() {
        return nextInt(JVM_RANDOM);
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed int value
     * from the given <code>random</code> sequence.</p>
     *
     * @param random the Random sequence generator.
     * @return the random int
     */
    public static int nextInt(Random random) {
        return random.nextInt();
    }
    
    /**
     * <p>Returns a pseudorandom, uniformly distributed int value
     * between <code>0</code> (inclusive) and the specified value
     * (exclusive), from the Math.random() sequence.</p>
     *
     * @param n  the specified exclusive max-value
     * @return the random int
     */
    public static int nextInt(int n) {
        return nextInt(JVM_RANDOM, n);
    }
    
    /**
     * <p>Returns a pseudorandom, uniformly distributed int value
     * between <code>0</code> (inclusive) and the specified value
     * (exclusive), from the given Random sequence.</p>
     *
     * @param random the Random sequence generator.
     * @param n  the specified exclusive max-value
     * @return the random int
     */
    public static int nextInt(Random random, int n) {
        // check this cannot return 'n'
        return random.nextInt(n);
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed long value
     * from the Math.random() sequence.</p>
     *
     * @return the random long
     */
    public static long nextLong() {
        return nextLong(JVM_RANDOM);
    }

    /**
     * <p>Returns the next pseudorandom, uniformly distributed long value
     * from the given Random sequence.</p>
     *
     * @param random the Random sequence generator.
     * @return the random long
     */
    public static long nextLong(Random random) {
        return random.nextLong();
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed boolean value
     * from the Math.random() sequence.</p>
     *
     * @return the random boolean
     */
    public static boolean nextBoolean() {
        return nextBoolean(JVM_RANDOM);
    }

    /**
     * <p>Returns the next pseudorandom, uniformly distributed boolean value
     * from the given random sequence.</p>
     *
     * @param random the Random sequence generator.
     * @return the random boolean
     */
    public static boolean nextBoolean(Random random) {
        return random.nextBoolean();
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed float value
     * between <code>0.0</code> and <code>1.0</code> from the Math.random()
     * sequence.</p>
     *
     * @return the random float
     */
    public static float nextFloat() {
        return nextFloat(JVM_RANDOM);
    }

    /**
     * <p>Returns the next pseudorandom, uniformly distributed float value
     * between <code>0.0</code> and <code>1.0</code> from the given Random
     * sequence.</p>
     *
     * @param random the Random sequence generator.
     * @return the random float
     */
    public static float nextFloat(Random random) {
        return random.nextFloat();
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed float value
     * between <code>0.0</code> and <code>1.0</code> from the Math.random()
     * sequence.</p>
     *
     * @return the random double
     */
    public static double nextDouble() {
        return nextDouble(JVM_RANDOM);
    }

    /**
     * <p>Returns the next pseudorandom, uniformly distributed float value
     * between <code>0.0</code> and <code>1.0</code> from the given Random
     * sequence.</p>
     *
     * @param random the Random sequence generator.
     * @return the random double
     */
    public static double nextDouble(Random random) {
        return random.nextDouble();
    }
    
}