com.mgmtp.jfunk.common.random.MathRandom.java Source code

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Here is the source code for com.mgmtp.jfunk.common.random.MathRandom.java

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/*
 * Copyright (c) 2015 mgm technology partners GmbH
 *
 * 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.mgmtp.jfunk.common.random;

import static java.lang.Math.abs;
import static java.lang.Math.min;

import java.util.Calendar;
import java.util.Date;
import java.util.Random;
import java.util.concurrent.atomic.AtomicLong;

import org.apache.commons.lang3.time.DateUtils;

/**
 * Utility class for generating random numbers
 * 
 */
public class MathRandom {

    private final Random random;
    private final long seed;

    /**
     * Will be increased on each access to get an unique seed value
     */
    private static final AtomicLong SEED_UNIQUIFIER = new AtomicLong(3214984168468513L);

    public MathRandom() {
        seed = nextSeed();
        random = new Random(seed);
    }

    public MathRandom(final long seed) {
        this.seed = seed;
        random = new Random(seed);
    }

    public static long nextSeed() {
        return SEED_UNIQUIFIER.addAndGet(System.nanoTime());
    }

    public long getSeed() {
        return seed;
    }

    public Random getRandom() {
        return random;
    }

    /**
     * Returns a random boolean value
     */
    public boolean getBoolean() {
        return random.nextBoolean();
    }

    /**
     * Returns a random integer number in the range of [0, max].
     * 
     * @param max
     *            maximum value for generated number
     */
    public int getInt(final int max) {
        if (max <= 0) {
            return 0;
        }
        double rnd = (max + 1) * random.nextDouble();
        return (int) rnd;
    }

    /**
     * Returns a random integer number in the range of [min, max].
     * 
     * @param min
     *            minimum value for generated number
     * @param max
     *            maximum value for generated number
     */
    public int getInt(final int min, final int max) {
        return min(min, max) + getInt(abs(max - min));
    }

    /**
     * Returns a random decimal number in the range of [0, max].
     * 
     * @param max
     *            maximum value for generated number
     */
    public double getDouble(final double max) {
        return (max + Math.ulp(max)) * random.nextDouble();
    }

    /**
     * Returns a random decimal number in the range of [min, max].
     * 
     * @param min
     *            minimum value for generated number
     * @param max
     *            maximum value for generated number
     */
    public double getDouble(final double min, final double max) {
        return min(min, max) + getDouble(abs(max - min));
    }

    /**
     * Returns a random integer number in the range of [0, max].
     * 
     * @param max
     *            maximum value for generated number
     */
    public long getLong(final long max) {
        if (max <= 0) {
            return 0;
        }
        double rnd = (max + 1) * random.nextDouble();
        return (long) rnd;
    }

    /**
     * Returns a random integer number in the range of [min, max].
     * 
     * @param min
     *            minimum value for generated number
     * @param max
     *            maximum value for generated number
     */
    public long getLong(final long min, final long max) {
        return min(min, max) + getLong(abs(max - min));
    }

    /**
     * Returns a random date in the range of [min, max].
     * 
     * @param min
     *            minimum value for generated date
     * @param max
     *            maximum value for generated date
     */
    public Date getDate(final Date min, final Date max) {
        return getDate(min.getTime(), max.getTime());
    }

    /**
     * Returns a random date in the range of [min, max].
     * 
     * @param min
     *            minimum value for generated date (in milliseconds)
     * @param max
     *            maximum value for generated date (in milliseconds)
     */
    public Date getDate(final long min, final long max) {
        long millis = getLong(min, max);
        return DateUtils.truncate(new Date(millis), Calendar.DATE);
    }

    /**
     * Returns a random Calendar object in the range of [min, max].
     * 
     * @param min
     *            minimum value for generated Calendar object
     * @param max
     *            maximum value for generated Calendar object
     */
    public Calendar getCalendar(final Calendar min, final Calendar max) {
        long millis = getLong(min.getTimeInMillis(), max.getTimeInMillis());
        return createCalendar(millis);
    }

    /**
     * Returns a random Calendar object in the range of [min, max].
     * 
     * @param min
     *            minimum value for generated Calendar object
     * @param max
     *            maximum value for generated Calendar object
     */
    public Calendar getCalendar(final Date min, final Date max) {
        long millis = getLong(min.getTime(), max.getTime());
        return createCalendar(millis);
    }

    /**
     * Returns a random Calendar object in the range of [min, max].
     * 
     * @param min
     *            minimum value for generated Calendar object (in milliseconds)
     * @param max
     *            maximum value for generated Calendar object (in milliseconds)
     */
    public Calendar getCalendar(final long min, final long max) {
        long millis = getLong(min, max);
        return createCalendar(millis);
    }

    private Calendar createCalendar(final long millis) {
        Calendar cal = Calendar.getInstance();
        cal.setTimeInMillis(millis);
        return DateUtils.truncate(cal, Calendar.DATE);
    }
}