code: /*
   * 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: JVMRandom.java 471626 2006-11-06 04:02:09Z bayard $
   */
  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 &lt;= 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 &lt;= 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();
      }
      
  }
  