About Question enthuware.ocpjp.v8.2.1871 :

[pavvel]

I understood why the third option works - process(fnames, TestClass::size);
Due to the example below:

Code: Select all

class Main {
    public static void main(String[] args) {
        I i1 = A::m;
    }
    @FunctionalInterface
    interface I{
        void method();
    }
    class A {
        public static void m() {}
    }
}