How to pass a method in Java?

Question

Java

Standard wrappers from java.util.function.* do not interest me.
The question is how to pass a method through interfaces.

How to pass a method like this?
I know for sure that it is possible, I saw the code somewhere.

Answer 1

What is fn? In the code you provided, this name is not defined anywhere. Also, Test takes two parameters, and you pass one. I suspect that you wanted
Test(Main::Func, 475)