Java BigInteger probablePrime() method

The probablePrime() method of Java BigInteger class is used to find a probably prime number of any bit length. This method returns a positive BigInteger that is probably prime, with the specified bitLength.

Syntax:

Parameter:

bitLength- bitLength of the returned BigInteger.

rnd- source of random bits used to select candidates to be tested for primality.

Returns:

This method returns a BigInteger of bitLength bits that is probably prime.

Exception:

ArithmeticException- if bitLength < 2.

Note: The probability that a BigInteger returned by this method is composite does not exceed 2^-100.

Example 1

import java.math.BigInteger;
import java.util.Random;
public class BigIntegerProbablePrimeExample1 {
	public static void main(String[] args) {
	       // create a BigInteger object
	      BigInteger big1;
	      // create and assign value to bitLength
	      int bitLength = 4;
	      // create a random object
	      Random rnd = new Random();
	      // assign probablePrime result to big1 using bitLength and rnd
	      // static method is called using class name
	      big1 = BigInteger.probablePrime(bitLength,rnd);
	      String str = "ProbablePrime of bitlength "+bitLength+" is "+big1;
	      // print big1 value
	      System.out.println(str);
	}
}

Test it Now

Output:

ProbablePrime of bitlength 4 is 11

Example 2

import java.math.BigInteger;
import java.util.Random;
public class BigIntegerProbablePrimeExample2 {
	public static void main(String[] args) {
	       // create a BigInteger object
	      BigInteger big1;
	      // create and assign value to bitLength
	      int bitLength = 1;
	      // create a random object
	      Random rnd = new Random();
	      // assign probablePrime result to big1 using bitLength and rnd
	      // static method is called using class name
	      big1 = BigInteger.probablePrime(bitLength, rnd);
	      String str = "ProbablePrime of bitlength "+bitLength+" is "+big1;
	      // print big1 value
	      System.out.println(str);
	}
}

Test it Now

Output:

Exception in thread "main" java.lang.ArithmeticException: bitLength < 2
        at java.math.BigInteger.probablePrime(BigInteger.java:695)
        at BigIntegerProbablePrimeExample2.main(BigIntegerProbablePrimeExample2.java:13)

Example 3

import java.math.BigInteger;
import java.util.Random;
public class BigIntegerProbablePrimeExample3 {
	public static void main(String[] args) {
	       // create a BigInteger object
	      BigInteger big1;
	      // create and assign value to bitLength
	      int bitLength = 10;
	      // create a random object
	      Random rnd = new Random();
	      // assign probablePrime result to big1 using bitLength and rnd
	      // static method is called using class name
	      big1 = BigInteger.probablePrime(bitLength, rnd);
	      String str = "ProbablePrime of bitlength "+bitLength+" is "+big1;
	      // print big1 value
	      System.out.println(str);
	}
}

Test it Now

Output: