The complete rule is below.

Here is the complete math-like definition for the Fibonacci series.
There are __two base cases__.
This is fine.
Recursion breaks problems into smaller pieces.
After enough breaking, all that remains are the base cases that
can be solved immediately.
There can be any number of base cases.

fib( 1 ) = 1 (base case) fib( 2 ) = 1 (base case) fib( N ) = fib( N-1 ) + fib( N-2 )

We have a math-like definition. Creating a Java method to implement it should be a nearly mechanical translation from math to Java.

public int fib( int n ) { if ( ________ ) return _______; else if ( ________ ) return _______; else return ________ + ________; }