Can an abstract class implement an interface

[Gaurav Chikara]

Hi
I could have tried it instead of asking on forum but due to some sw problem I could not do
Can any one pls tell me whether it is legitimate or not?
abstract class says it implemnets an interface but instaed of impleneting the methods it declares them as abstract
Is it legal?

[Jim Yingst]

Yes. Any concrete subclass will have to implement the abstract methods, so they will be implemented by the time any JVM is asked to invoke the method. It's just a special case of implementing by forcing subclasses to implement for you.

[Anonymous]

Originally posted by Gaurav Chikara:
abstract class says it implemnets an interface but instaed of impleneting the methods it declares them as abstract
Is it legal?

As Jim already explained; yes this is perfectly legal. Even more, your abstract class doesn't even have to mention the methods in the interface it 'implements' (mind the quotes), e.g. the following:

interface SomeInterface {
   void foo();
   int  bar();
}
public abstract class YourClass implements SomeInterface {
   // no mention of foo() and bar() here
}

is perfectly legal. If a subclass of YourClass wants to be concrete class, it has to implement both foo() and bar().
kind regards