Generates pseudo-random integer from specific range. - Java java.util

Java examples for java.util:Random

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Description

Generates pseudo-random integer from specific range.

Demo Code


//package com.java2s;

public class Main {
    /**//from w  w  w  .j  a  v a2 s  .  c  o m
     * Generates pseudo-random integer from specific range. Generated number is
     * great or equals to min parameter value and less then max parameter value.
     * Uses {@link Math#random()}.
     * 
     * @param min
     *            lower (inclusive) boundary
     * @param max
     *            higher (exclusive) boundary
     * 
     * @return pseudo-random value
     */
    public static int randomInt(int min, int max) {
        return min + (int) (Math.random() * (max - min));
    }

    /**
     * Returns a <code>double</code> value with a positive sign, greater than or
     * equal to <code>0.0</code> and less than <code>1.0</code>. Returned values
     * are chosen pseudorandomly with (approximately) uniform distribution from
     * that range.
     * 
     * <p>
     * When this method is first called, it creates a single new
     * pseudorandom-number generator, exactly as if by the expression
     * <blockquote>
     * 
     * <pre>
     * new java.util.Random
     * </pre>
     * 
     * </blockquote> This new pseudorandom-number generator is used thereafter
     * for all calls to this method and is used nowhere else.
     * </p>
     * 
     * <p>
     * This method is properly synchronized to allow correct use by more than
     * one thread. However, if many threads need to generate pseudorandom
     * numbers at a great rate, it may reduce contention for each thread to have
     * its own pseudorandom-number generator.
     * </p>
     * 
     * @return a pseudorandom <code>double</code> greater than or equal to
     *         <code>0.0</code> and less than <code>1.0</code>.
     * 
     * @see java.util.Random#nextDouble()
     */
    public static double random() {
        return Math.random();
    }
}

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