Find sum

public class Solution {
    public static int find(String s) {
        if (s == null) return 0;

        int maxLen = 0;
        for (int i = 1; i < s.length(); i++) {
            int start = i - 1, end = i;
            int leftSum = 0, rightSum = 0, len = 0;
            while (start - len  >= 0 && end + len < s.length()) {
                leftSum += Character.getNumericValue(s.charAt(start - len));
                rightSum += Character.getNumericValue(s.charAt(end + len));
                if (leftSum == rightSum) {
                    //update maxLen if we have found one 
                    maxLen = Math.max(maxLen, 2 * (len + 1));
                }
                len++;//we always go as far as i can
            }
        }
        return maxLen;
    }
}