About Java subinterface subtype

Question

This seems a basic java question.

I have one interface, Pipeline, which has a method execute(Stage).

Then I create a sub interface to extend from Pipeline, say BookPipeline, I like the method to be execute(BookStage).

BookStage extends from Stage.

Seems this kind of definition could not pass java compile.

Any suggestion on that?

Answer 1

You may want to consider using generics.

public interface Pipeline<T extends Stage> {
     public void execute(T stage);
}

public interface BookPipeline extends Pipeline<BookStage> {
     @Override
     public void execute(BookStage stage);
}