How to add two numbers of any length in java?

Question

How to add two numbers of any length in java?

Say for example, in java long size is 64 bit. So the maximum range is -9223372036854775808 to 9223372036854775807. Am i

Answer 1

public class AddNumbers {
    public static void main(String args[]) {
        String a = new String("3999988889999999995555558888999444333333333222229998877666555444888888");
        String b = new String("56867865876989679765465456412332199");
        int loop1 = 0;
        int loop2 = 0;
        StringBuilder sum = new StringBuilder("");
        int carry = 0;
        for (loop1 = a.length() - 1, loop2 = b.length() - 1; loop1 >= 0 || loop2 >= 0; loop1--, loop2--) {
            int indiv1 = 0;
            if (loop1 >= 0)
                indiv1 = Integer.parseInt("" + a.charAt(loop1));
            int indiv2 = 0;
            if (loop2 >= 0)
                indiv2 = Integer.parseInt("" + b.charAt(loop2));
            int summation = indiv1 + indiv2 + carry;
            double d = Math.floor(summation / 10);
            carry = (int) d;
            int sum2 = summation % 10;
            sum.append(sum2);
        }
        System.out.println(sum.reverse());
    }
}