On Tue, Aug 11, 2009 at 10:44 AM, Jörn Kottmann<kottm...@gmail.com> wrote:
> Adam Lally wrote:
>>
> Lets say we have an interface Box{Number getNumber()}
> then we could have a class BoxImpl implements Box{Integer getNumber(){...}}.
>
> Now I only would have to cast once
> Box box = ...;
> BoxImpl boxImpl = (BoxImpl) box;
>
> now
> Integer number = boxImpl.getNumber()
> would work. Sure if you do the same for CAS and CASImpl
> you safe lots of casts.
>
> The same does not work for a getNumbers which
> returns a List<Number> or Iterator<Number>
> without also allowing down casting.
>
Well, true, but it does not really create an analogous solution if you do:
interface Box{List<T extends Number> getNumberList()}
class BoxImpl{List<Integer> numberList()}
Because a client could call
List<Integer> x = box.getNumberList()
whether or not box was actually a BoxImpl.
-Adam
