CODEWITHSUNDEEP
javagenerics
TheKojuEffect
TheKojuEffect

Reputation: 21081

Java Generics: Implement multiple sub-interfaces of an generic interface

I've following codes. 


interface Observer<T> {
    void update();
}



interface FirstClassObserver extends Observer<FirstClass>{ }



interface SecondClassObserver extends Observer<SecondSecond> { }

Now, I'm required to do as follows.


class MainClass implements FirstClassObserver, SecondClassObserver {
}

But Eclipse give following problem with the code.

The interface Observer cannot be implemented more than once with different arguments: FirstClassObserver<FirstClass> and SecondClassObserver<SecondClass>

Is there a way that I can write my MainClass like


class MainClass implements FirstClassObserver, SecondClassObserver {
   @Override
   void FirstClassObserver::update() { /* ... / }
   @Override
   void SecondClassObserver::update() { / ... */ }
}

Upvotes: 1

Views: 823

Answers (1)

TheKojuEffect
TheKojuEffect

Reputation: 21081

According to @Ted's comment. Because of type erasure, you aren't going to be able to do this. Basically, all generic type parameters end up as Object in the compiled byte code.

Also according to @assylias's comment, there can be ambiguous situation as whose instance of update() method to call MainClass.update() is invoked.

Upvotes: 4

Related Questions