| /* |
| * 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>JVMRandom</code> is a wrapper that supports all possible |
| * Random methods via the {@link java.lang.Math#random()} method |
| * and its system-wide {@link Random} object.</p> |
| * |
| * @since 2.0 |
| * @version $Id$ |
| */ |
| public final class JVMRandom extends Random { |
| |
| /** |
| * Required for serialization support. |
| * |
| * @see java.io.Serializable |
| */ |
| private static final long serialVersionUID = 1L; |
| |
| /** |
| * Ensures that only the constructor can call reseed. |
| */ |
| private boolean constructed = false; |
| |
| /** |
| * Constructs a new instance. |
| */ |
| public JVMRandom() { |
| this.constructed = true; |
| } |
| |
| /** |
| * Unsupported in 2.0. |
| * |
| * @param seed ignored |
| * @throws UnsupportedOperationException |
| */ |
| public synchronized void setSeed(long seed) { |
| if (this.constructed) { |
| throw new UnsupportedOperationException(); |
| } |
| } |
| |
| /** |
| * Unsupported in 2.0. |
| * |
| * @return Nothing, this method always throws an UnsupportedOperationException. |
| * @throws UnsupportedOperationException |
| */ |
| public synchronized double nextGaussian() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| /** |
| * Unsupported in 2.0. |
| * |
| * @param byteArray ignored |
| * @throws UnsupportedOperationException |
| */ |
| public void nextBytes(byte[] byteArray) { |
| throw new UnsupportedOperationException(); |
| } |
| |
| /** |
| * <p>Returns the next pseudorandom, uniformly distributed int value |
| * from the Math.random() sequence.</p> |
| * |
| * @return the random int |
| */ |
| public int nextInt() { |
| return nextInt(Integer.MAX_VALUE); |
| } |
| /** |
| * <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 |
| * @throws IllegalArgumentException when <code>n <= 0</code> |
| */ |
| public int nextInt(int n) { |
| if (n <= 0) { |
| throw new IllegalArgumentException( |
| "Upper bound for nextInt must be positive" |
| ); |
| } |
| // TODO: check this cannot return 'n' |
| return (int)(Math.random() * n); |
| } |
| /** |
| * <p>Returns the next pseudorandom, uniformly distributed long value |
| * from the Math.random() sequence.</p> |
| * @return the random long |
| */ |
| public long nextLong() { |
| // possible loss of precision? |
| return nextLong(Long.MAX_VALUE); |
| } |
| |
| |
| /** |
| * <p>Returns a pseudorandom, uniformly distributed long 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 long |
| * @throws IllegalArgumentException when <code>n <= 0</code> |
| */ |
| public static long nextLong(long n) { |
| if (n <= 0) { |
| throw new IllegalArgumentException( |
| "Upper bound for nextInt must be positive" |
| ); |
| } |
| // TODO: check this cannot return 'n' |
| return (long)(Math.random() * n); |
| } |
| |
| /** |
| * <p>Returns the next pseudorandom, uniformly distributed boolean value |
| * from the Math.random() sequence.</p> |
| * |
| * @return the random boolean |
| */ |
| public boolean nextBoolean() { |
| return Math.random() > 0.5; |
| } |
| /** |
| * <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 float nextFloat() { |
| return (float)Math.random(); |
| } |
| /** |
| * <p>Synonymous to the Math.random() call.</p> |
| * |
| * @return the random double |
| */ |
| public double nextDouble() { |
| return Math.random(); |
| } |
| |
| } |