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From "Alexey Varlamov" <alexey.v.varla...@gmail.com>
Subject Re: [classlib] Sun compiler change?
Date Tue, 29 Aug 2006 04:41:07 GMT
2006/8/29, Spark Shen <smallsmallorgan@gmail.com>:
> Krzysztof Sobolewski 写道:
> > Spark Shen wrote:
> >
> >
> >> Did you (refer to thread [app] ant with ecj) put
> >>
> >> Eclipse compiler JAR on Ant's
> >> execution classpath to execute the javac task.
> >>
> >> If so, may be that's why It always gives you "unchecked cast" warning,
> >> no errors.
> >>
> >
> > Well, I created a new EnumSet class in completly unrelated environment... So
> > it is perfectly possible that there's a classpath conflict somewhere. I
> > can't verify that because don't have the Harmony build here :)
> >
> > BTW: another experiment revealed that
> > EnumSet<? extends Enum<E>> set = (EnumSet<? extends Enum<E>>)collection;
> > compiles without warnings. No matter how much I think I understand generics,
> > there's always something that surprises me ;)
> >
> Conceptually speaking, I think EnumSet<? extends Enum<E>> still has
> potential pitfall:
>
> In the signature of addAll(Collection<? extends E> collection) method, ?
> denotes subclass of E.
> While in EnumSet<? extends Enum<E>>, ? denotes subclass of Enum<E>.
But
> consider the relationship
> between E and Enum<E>, E is subclass of Enum<E>. So, we can not
> guarantee that subclass of E is definitely
> subclass of Enum<E>.

Hmm, as E is a subclass of Enum<E>, subclasses of E definitely have
Enum<E> among ancestors ;)

>
> Correct me if I am wrong.
>
> Best regards
> > -KS
> >
> >
>
>
> --
> Spark Shen
> China Software Development Lab, IBM
>
>
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