MatsimRandom.java

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/* *********************************************************************** *
 * project: org.matsim.*
 * MatsimRandom.java
 *                                                                         *
 * *********************************************************************** *
 *                                                                         *
 * copyright       : (C) 2008 by the members listed in the COPYING,        *
 *                   LICENSE and WARRANTY file.                            *
 * email           : info at matsim dot org                                *
 *                                                                         *
 * *********************************************************************** *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *   See also COPYING, LICENSE and WARRANTY file                           *
 *                                                                         *
 * *********************************************************************** */

package org.matsim.core.gbl;

import java.util.Random;


public abstract class MatsimRandom {
    private static final long DEFAULT_RANDOM_SEED = 4711;

    private static long lastUsedSeed = DEFAULT_RANDOM_SEED;
    private static int internalCounter = 0;

    private static final Random random = new Random(DEFAULT_RANDOM_SEED);

    public static void reset() {
        reset(DEFAULT_RANDOM_SEED);
    }

    public static void reset(final long seed) {
        lastUsedSeed = seed;
        internalCounter = 0;
        getRandom().setSeed(seed);
//      prepareRNG(random);
    }
    public static Random getRandom() {
        return random;
    }

    public static Random getLocalInstance() {
        internalCounter++;
        Random r = new Random(lastUsedSeed + internalCounter*23l);
        prepareRNG(r);
        return r;
    }

    private static void prepareRNG(final Random rng) {
        for (int i = 0; i < 100; i++) {
            rng.nextDouble();
        }
    }
}