It's another level of abstract thinking to get to where you're extending AND implementing. :-) I tutored a CS student in java last year (and it has been a while since I was doing full time hard core java) and was myself tutored in the process. Not only is there much to learn, there's much to forget. And on top of that, modern CS studies are getting deep into patterns that go well beyond our basic understanding of classes and interfaces. Both comforting, in that we know there are more adventures ahead, and humbling.
It's another level of abstract thinking to get to where you're extending AND implementing. :-) I tutored a CS student in java last year (and it has been a while since I was doing full time hard core java) and was myself tutored in the process. Not only is there much to learn, there's much to forget. And on top of that, modern CS studies are getting deep into patterns that go well beyond our basic understanding of classes and interfaces. Both comforting, in that we know there are more adventures ahead, and humbling.