Adding two numbers without + operator (Clarification)

Question

I know that we can use the logic of binary adder where Sum = a XOR b and Carry = a AND b

I have also got a solution:

Answer 1

public class AddSub {

    int sum=0,carry=0;
    public static void main(String[] args) {
        System.out.println("Add "+new AddSub().addition(93,5));
        System.out.println("Sub "+new AddSub().subtraction(7,60));
        System.out.println("Sub "+new AddSub().multiplication(9,60));
    }

    public int addition(int a, int b)
    {
        if(b==0)
        {
            return a;
        }
        else
        {
             sum = a^b;
             carry = (a&b)<<1;
            return addition(sum,carry);         
        }
    }

    public int subtraction(int a, int b){

        return addition(a,addition(~b,1));

    }

    public int multiplication(int a, int b){       
        for(int i=0;i