The complete method is seen below.
public int fib( int n )
{
if ( n == 1 )
return 1;
else if ( n == 2 )
return 1;
else
return fib( n-1 ) + fib( n-2 );
}
It may worry you that the code for fib(int n) calls itself twice, in
fib(n-1) and fib(n-2).
This is fine.
Look at the math-like definition. Play with it until you understand it.
The program says the same thing but uses a different language (Java) to say it.
It is the job of the Java system to make sure that you get the computation that you ask for. All you have to do is ask for it correctly.
Could you think about fib(n) dynamically?