Java中的递归

Question

Given this method call:

public class MainClass {

public static void main(String[] args) {
    System.out.println(fib(3));
}

private static int fib(int i) {
     System.out.println("Into fib with i = " + i);

    if (i < 2) {
        System.out.println("We got here");
        return i;
    }
    return fib(i-1) + fib(i-2); 
}

 }

I expected:

* fib(i-1) to return 2
* fib(i-2) to return 1
* return 2 + 1 to return 3

Result:

2

This is the output of console:

Into fib with i = 3
Into fib with i = 2
Into fib with i = 1
We got here
Into fib with i = 0
We got here

I understand everything up to this part:

Into fib with i = 0

When could have i ever been 0?

Answer 1

fib(3) calls fib(2) . When you call fib(2) , it will call fib(i-1) and fib(i-2) , that is, fib(1) and fib(0) .