Tracing order of execution in Java

I have a factorial code

class FactorialTest {

    public static void main(String args[]){
        System.out.println(factorial(10));
    }

    public static int factorial(int N){
        if (N <= 1) return 1;
        return N*factorial(N-1);
    }
}

It was traced using Trace, and this is the output:

Does that mean that recursion part always done first开发者_高级运维, and the multipication is later?

---

The recursion must be done first, since it is an argument to the multiplication. Before the recursion gets done, what would even be multiplied?

I don't think your Trace output tells you that, though. I'm answering only after reading the code.

---

It's possible to implement factorial using tail recursion, but in your code the multiplication follows the recursive call so a tail cail optimization cannot be applied.

---

Of course the recursive call must be evaluated first. You are multiplying two expressions, one of which is simply a value (N) the other is a recursive call. Without making the call and getting the result first, how would you expect to multiply that to N?