Adding binary numbers

Question

Does anyone know how to add 2 binary numbers, entered as binary, in Java?

For example, 1010 + 10 = 1100.

Answer 1

class Sum{
    public int number;
    public int carry;

    Sum(int number, int carry){
        this.number = number; 
        this.carry = carry;
    }
}

public String addBinary(String a, String b) {

    int lengthOfA = a.length();
    int lengthOfB = b.length();

    if(lengthOfA > lengthOfB){
        for(int i=0; i<(lengthOfA - lengthOfB); i++){
            b="0"+b;
        }
    }
    else{
         for(int i=0; i<(lengthOfB - lengthOfA); i++){
            a="0"+a;
        }
    }

    String result = "";
    Sum s = new Sum(0,0);
    for(int i=a.length()-1; i>=0; i--){
        s = addNumber(Character.getNumericValue(a.charAt(i)), Character.getNumericValue(b.charAt(i)), s.carry);
        result = result + Integer.toString(s.number);
    }

    if(s.carry == 1) { result += s.carry ;}

    return new StringBuilder(result).reverse().toString();
}

Sum addNumber(int number1, int number2, int carry){
        Sum sum = new Sum(0,0);
        sum.number = number1 ^ number2 ^ carry;
        sum.carry = (number1 & number2) | (number2 & carry) | (number1 & carry);

        return sum;
}