Well, close, but not entirely correct. Any non-abstract subclass must override any supertype abstract method. This includes abstract methods of superclasses, and implemented interface methods (which are implicitly abstract).
My guess is that you are receiving a compile-time error about failure to implement an abstract method in a supertype that you can't seem to locate.
I assure you, the compiler is right - you'll have to provide more specific information to receive a more detailed answer.
Simply you must create a new class that starts like public <your-class name> extends <abstract-class-name> and define all the methods of the abstract class. So you can cast it anywhere like this abstract class. This is the only advantage...
i have alredy prepared for my certification, and my sjcp exam date is 3rd july.
my problem is only with the term "overiding". for non-abstract methods the term is fine. but for abstract method, which has no code or implementation in first place, how can the term overiding can be used when we are not overiding any code, any behaviour. So i think the more appropriate term would be implementing abstract methods, rather than overiding abstract method.
i only want to hear the other side of the story, and want justification of , why my argument is wrong, and the one of rules roundup right.