Leetcode#67||Add Binary

public class Solution {
public String addBinary(String a, String b) {
if (a.length() < b.length()) {
String temp = a;
a = b;
b = temp;
}

int iA = a.length() - 1;
int iB = b.length() - 1;

String result = "";

int carry = 0;

while (iB >= 0) {
int sum = (int)(a.charAt(iA) - '0') + (int)(b.charAt(iB) - '0') + carry;
result = String.valueOf(sum % 2) + result;
carry = sum / 2;

iB--;
iA--;
}

while (iA >= 0) {
int sum = (int)(a.charAt(iA) - '0') + carry;
result = String.valueOf(sum % 2) + result;
carry = sum / 2;
iA--;
}

if (carry == 1) {
result = "1" + result;
}

return result;
}
}