Java | Create an explicit addition function only using recursion and conditionals

Question

Preface

By finding some free time in my schedule, I quested myself into improving my recursion skills (unfortunately). As practice, I want to recreate a

Answer 1

public static int add(int a, int b) {
    if(b == 0) return a;
    int sum = a ^ b; //SUM of two integer is A XOR B
    int carry = (a & b) << 1;  //CARRY of two integer is A AND B
    return add(sum, carry);
}

Shamefully taken from here. All credit goes to its author.