com.google.gwt.user.client.Random.java Source code

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Here is the source code for com.google.gwt.user.client.Random.java

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/*
 * Copyright 2006 Google Inc.
 * 
 * Licensed 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 com.google.gwt.user.client;

/**
 * This class can be used as a substitute for {@link java.util.Random}. The
 * semantics differ in that the underlying browser's implementation is used. The
 * random generator cannot be seeded or otherwise used to reproduce a particular
 * sequence of results.
 */
public final class Random {

    /**
     * Returns true or false with roughly equal probability. The underlying
     * browser's random implementation is used.
     */
    public static native boolean nextBoolean() /*-{
                                               return Math.random() < 0.5;
                                               }-*/;

    /**
     * Returns a random <code>double</code> between 0 (inclusive) and 1
     * (exclusive). The underlying browser's random implementation is used.
     */
    public static native double nextDouble() /*-{
                                             return Math.random();
                                             }-*/;

    /**
     * Returns a random <code>int</code> between -2147483648 and 2147483647
     * (inclusive) with roughly equal probability of returning any particular
     * <code>int</code> in this range. The underlying browser's random
     * implementation is used.
     */
    public static native int nextInt() /*-{
                                       // "~~" forces the value to a 32 bit integer.
                                       return ~~(Math.floor(Math.random() * 4294967296) - 2147483648);
                                       }-*/;

    /**
     * Returns a random <code>int</code> between 0 (inclusive) and
     * <code>upperBound</code> (exclusive) with roughly equal probability of
     * returning any particular <code>int</code> in this range. The underlying
     * browser's random implementation is used.
     */
    public static native int nextInt(int upperBound) /*-{
                                                     // "~~" forces the value to a 32 bit integer.
                                                     return ~~(Math.floor(Math.random() * upperBound));
                                                     }-*/;

    /**
     * Not instantiable. Having different instances of this class would not be
     * meaningful because no state is stored and the common browser implementation
     * is shared.
     */
    private Random() {
    }
}