Geek asks and answers

Why in this case use the interface over the abstract class?

I read a blog post here: http://codeofdoom.com/wordpress/2009/02/12/learn-this-when-to-use-an-abstract-class-and-an-interface/

public interface Actor{
   Performance say(Line l);
}
public interface Director{
   Movie direct(boolean goodmovie);
}
public interface ActorDirector extends Actor, Director{
...
}

It says: In fact, there are Actors who are also Directors. If we use interfaces, not abstract classes. We could achieve the same using abstract classes. Unfortunately, the alternative will require up to 2 ^ n (where n is the number of attributes ) of possible combinations to support all the possibilities.

Question: why is an abstract class better here? and why 2 ^ n?

public abstract class ActorDirector implements Actor,Director{
}
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4 answers

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