Thread: Java recursion

Could someone help me understand this code? Thanks
So the program will print out

"Example 1: x = 20
20 > 10, therefore ... f(20) = f(20 - 3) + 2 = f(17) + 2
17 > 10, therefore ... f(17) = f(17 - 3) + 2 = f(14) + 2
14 > 10, therefore ... f(14) = f(14 - 3) + 2 = f(11) + 2
11 > 10, therefore ... f(11) = f(11 - 3) + 2 = f(8) + 2
8 <= 10, therefore ... f(8) = -5
f(20) = 3
"
How does the computer know to take -5 and + by 8? Thanks

class RecursiveMethods
{
    RecursiveMethods()          //default constructor
    {
    }
 
    public int fOf(int x)
    {
        if (x <= 10)                        //the base case
        {
            System.out.println(x + " <= 10, therefore ... f(" + x + ") = -5");
            return -5;
        }
        else
        {
            System.out.println(x + " > 10, therefore ... f(" + x + ") = f(" + x + " - 3) + 2 = f(" + (x -3) + ") + 2");
            return fOf(x-3) + 2;
        }
    }    
}
 
public class RecursionMethodTester
{
    public static void main(String[] args)
    {
        int x;
        RecursiveMethods rMethods = new RecursiveMethods();
 
        System.out.println("---------------------------------");
        System.out.println("       f(x - 3) + 2    if x >  10");
        System.out.println("f(x) = ");
        System.out.println("       -5              if x <= 10");
        System.out.println("---------------------------------");
        System.out.println();
 
        x = 20;
        System.out.println("Example 1:  x = " + x);
        System.out.println("f(" + x + ") = " + rMethods.fOf(x));
        System.out.println();

How can I make the computer display what it the value it seeing? I believe the computer are seeing value of x which are 17, 14,11, and 8.

I understand it when it it is replacing the value but what I don't understand is how the program take -5 + 8 without me adding the statement. Does the recursion record the value +2 each time it occur and automatically add it at the end? Thanks

I understand how the program work now with your explanation of what happen when a method call itself. Thanks you so much!