fib( 1 ) = 1 (base case) fib( 2 ) = 1 (base case) fib( N ) = fib( N-1 ) + fib( N-2 )
Above is the complete math-like definition for the Fibonacci series. There are two base cases. This is fine. There can be any number of base cases. As recursion proceedes, it breaks problems into smaller and smaller pieces. After enough breaking, all that remains are the base cases.
We now have a math-like definition. Creating a Java method to implement it should be a mechanical translation from math into Java.
Sharpen your translation skills by filling in those blanks.