Java.math.BigInteger.isProbablePrime() Method

Description

The java.math.BigInteger.isProbablePrime(int certainty) returns true if this BigInteger is probably prime, false if it's definitely composite. If certainty is ≤ 0, true is returned.

Declaration

Following is the declaration for java.math.BigInteger.isProbablePrime() method.

public boolean isProbablePrime(int certainty)

Parameters

certainty − a measure of the uncertainty that the caller is willing to tolerate: if the call returns true the probability that this BigInteger is prime exceeds (1 - 1/2^certainty). The execution time of this method is proportional to the value of this parameter.

Return Value

This method returns true if this BigInteger is probably prime, false if it's definitely composite.

Exception

NA

Example

The following example shows the usage of math.BigInteger.isProbablePrime() method.

package com.tutorialspoint;

import java.math.*;

public class BigIntegerDemo {

   public static void main(String[] args) {

      // create 3 BigInteger objects
      BigInteger bi1, bi2, bi3;

      // create 3 Boolean objects
      Boolean b1, b2, b3;

      // assign values to bi1, bi2
      bi1 = new BigInteger("7");
      bi2 = new BigInteger("9");

      // perform isProbablePrime on bi1, bi2
      b1 = bi1.isProbablePrime(1);
      b2 = bi2.isProbablePrime(1);
      b3 = bi2.isProbablePrime(-1);

      String str1 = bi1+ " is prime with certainity 1 is " +b1;
      String str2 = bi2+ " is prime with certainity 1 is " +b2;
      String str3 = bi2+ " is prime with certainity -1 is " +b3;

      // print b1, b2, b3 values
      System.out.println( str1 );
      System.out.println( str2 );
      System.out.println( str3 );
   }
}

Let us compile and run the above program, this will produce the following result −

7 is prime with certainity 1 is true
9 is prime with certainity 1 is false
9 is prime with certainity -1 is true