How is a Method reference compatible with functional interface with different implementing function names?

Question

Here, a reference to the static method isPrime( ) is passed as the first argument to numTest( ). This works because isPrime is compatible with the IntPredicate functional interf

Answer 1

This is an example of lambdas at work. It is new in java 8 and it basically allows the runtime to create an instance of the functional interface for you with the implementation you define.

Brian Goetz has written a doc on how lambdas (and method references) work at compile and runtime.