BigInteger modPow() Method in Java

Prerequisite: BigInteger Basics
The Java.math.BigInteger.modPow() method returns a BigInteger whose value is (this^exponent mod m ). 
If exponent == 1, the returned value is (this mod m) and if exponent < 0, the returned value is the modular multiplicative inverse of (this^-exponent). The method throws an ArithmeticException if m <= 0.
 

Syntax:  

public BigInteger modPow(BigInteger exponent, BigInteger m)

Parameters: The method accepts two parameters.  

• exponent: This parameter refers to the exponent.
• m: This parameter refers to the modulus.

Return Value: The method returns a BigInteger object whose value is ( this^exponent mod m ).
 

Exceptions:  

• ArithmeticException: If (m <= 0) or the exponent is negative and this BigInteger is not relatively prime to m.

Examples: 

Input: biginteger1 = 23895 
                        exponent = 15
                        biginteger2 = 14189
Output: 344
Explanation:
result = biginteger1.modPow(exponent, biginteger2)
23895^15 % 14189 = 344

Input: biginteger1 = 6547890621
       exponent = 4532415
       biginteger2 = 76543278906
Output: 1039609179
Explanation:
6547890621^4532415 % 76543278906 = 1039609179

Below program illustrates the Java.math.BigInteger.modPow() method: 
 

// Code to illustrate modpow() method of BigInteger 
import java.math.*;
import java.util.Scanner;

public class GFG {

    public static void main(String[] args)
    {

        // Create 3 BigInteger objects
        BigInteger biginteger1, biginteger2, result;

        // Initializing all BigInteger Objects
        biginteger1 = new BigInteger("23895");
        biginteger2 = new BigInteger("14189");
        BigInteger exponent = new BigInteger("15");

        // Perform modPow operation on the objects and exponent
        result = biginteger1.modPow(exponent, biginteger2);
        String expression = biginteger1 + "^" + exponent + " % "
                            + biginteger2 + " = " + result;

        // Displaying the result
        System.out.println(expression);
    }
}

23895^15 % 14189 = 344

Reference: https://docs.oracle.com/javase/7/docs/api/java/math/BigInteger.html#abs()