Is there a way to guarantee an interface extends a class in Java?

Question

Suppose I have the following situation:

public abstract class Vehicle {
  public void turnOn() { ... }
}

public interface Flier {
  public void fly();
}
         


        

Answer 1

1. Define a new Package
2. Create a new interface (ie. HiddenOne) with scope "default" with a method "implementMe(HiddenOne)"
3. Move Vehicle and Flier to the new Package.
4. Inherit Vehicle and Flier from HiddenOne
5. Implement the method implementMe in Vehicle.

Now: Whenever you like to implement from "Flier" you must extends from Vehicle ! (because only Vehicle can implement implementMe).

This is tricky but works great.