Enforcing return type for an class that implements an interface

Question

How do I enforce that the method getFoo() in the implementing class, returns a list of the type of same implementing class.

public interface Bar{
     ....
          


        

Answer 1

You should infer the generic on Bar:

public interface Bar {
  ...
  List getFoo();
}

You can just parameterize the method, but that will not ensure that the return type matches that of the class.