String add

gistfile1.txt

class Solution {
    public String addStrings(String num1, String num2) {
        String longString = null;
        String shortSting = null;

        if (num1.length() >= num2.length()) {
            longString = num1;
            shortSting = num2;
        } else {
            longString = num2;
            shortSting = num1;
        }

        int big = longString.length();
        int small = shortSting.length();
        int carry = 0;
        char[] ra = new char[big + 1];

        for (int i = 0; i < small; i++) {
            int b = Character.getNumericValue(longString.charAt(big - i - 1));
            int s = Character.getNumericValue(shortSting.charAt(small - i - 1));
            ra[big - i] = Character.forDigit((b + s + carry) % 10, 10);
            carry = (b + s + carry) / 10;
        }

        for (int i = 0; i < (big - small); i++) {
            int b = Character.getNumericValue(longString.charAt(big - small - i -
                        1));
            ra[big - small - i] = Character.forDigit((b + carry) % 10, 10);
            carry = (b + carry) / 10;
        }

        if (carry != 0) {
            ra[0] = Character.forDigit(carry % 10, 10);
        }

        String ret = new String(ra).trim();

        return ret;
    }
}