Project Euler Problem 16 - Power digit sum

ProjectEulerProblem16.java

package com.company.ProjectEuler;

import java.math.BigInteger;

/**
 * Created by Adam Leathorn on 23/03/2017.
 */
public class ProjectEulerProblem16
{
    public ProjectEulerProblem16() {
        int x = 2;
        int y = 1000;

        String power = calculatePower(x, y).toString();

        System.out.println(x + "^"+y+" is:");
        System.out.println(power);
        System.out.println("The sum of the digits of " + x + "^"+y+" is:");
        System.out.println(addDigitsFromString(power));
    }

    public BigInteger calculatePower(int x, int y) {
        BigInteger result = new BigInteger(String.valueOf(x));
        BigInteger bigX = new BigInteger(String.valueOf(x));

        for(int i = 2; i <= y; i++) {
            result = result.multiply(bigX);
        }

        return result;
    }

    private long addDigitsFromString(String nums) {
        long numbers = 0;

        for (int i = 0; i < nums.length(); i++) {
            numbers += nums.charAt(i) - '0';
        }

        return numbers;
    }
}