Generating random numbers in Java

We can generate random numbers using three ways in Java.

• Using java.util.Random class − Object of Random class can be used to generate random numbers using nextInt(), nextDouble() etc. methods.

• Using java.lang.Math class − Math.random() methods returns a random double whenever invoked.

• Using java.util.concurrent.ThreadLocalRandom class − ThreadLocalRandom.current().nextInt() method and similar othjer methods return a random numbers whenever invoked.

Example

import java.util.Random; import java.util.concurrent.ThreadLocalRandom; public class Tester {    public static void main(String[] args) {       generateUsingRandom();       generateUsingMathRandom();       generateUsingThreadLocalRandom();    }    private static void generateUsingRandom() {       Random random = new Random();       //print a random int within range of 0 to 10.       System.out.println(random.nextInt(10));       //print a random int       System.out.println(random.nextInt());       //print a random double       System.out.println(random.nextDouble());    }    private static void generateUsingMathRandom() {       //print a random double       System.out.println(Math.random());    }    private static void generateUsingThreadLocalRandom() {       //print a random int within range of 0 to 10.       System.out.println(ThreadLocalRandom.current().nextInt(10));       //print a random int       System.out.println(ThreadLocalRandom.current().nextInt());       //print a random double       System.out.println(ThreadLocalRandom.current().nextDouble());    } }

Output

9 -1997411886 0.7272728969835154 0.9400193333973254 6 852518482 0.13628495782770622