How to generate large random numbers in Java?

For large random numbers, use BigInteger type in Java. At first, create a Random object −

Random randNum = new Random();

Now, declare a byte array and generate random bytes −

byte[] b = new byte[max]; randNum.nextBytes(b);

Now, generate a large random number with BigInteger type −

BigInteger bigInt = new BigInteger(b);

Example

 Live Demo

import java.math.BigInteger; import java.util.Random; public class Demo {    public static void main(String... a) {       int max = 10;       Random randNum = new Random();       byte[] b = new byte[max];       randNum.nextBytes(b);       // BigInteger type       BigInteger bigInt = new BigInteger(b);       System.out.println("Very large random number = "+bigInt);    } }

Output

Very large random number = 283258678185163472552410