Hi Friend,

Try this:

import java.math.*;
import java.util.*;

class SumOfAlternateDigits {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter Number: ");
        BigInteger bi = input.nextBigInteger();
        int num = 0;
        String strSum = bi.toString();
        for (int i = 0; i < strSum.length(); i += 2) {
            char ch = strSum.charAt(i);
            int n = Integer.parseInt(Character.toString(ch));
            num += n;
        }
        System.out.println("Sum of Alternate digits is: " + num);
    }
}

Thanks