Binary Addition and Subtraction

static String add(int a, int b) {

    String s1 = Integer.toString(a);
    String s2 = Integer.toString(b);
    int number0 = Integer.parseInt(s1, 2);
    int number1 = Integer.parseInt(s2, 2);

    int sum = number0 + number1;
    String ans = Integer.toBinaryString(sum);

    return ans;
}

System.out.println(add(1,1));
System.out.println(add(1,10));
System.out.println(add(10,110));

10
11
1000