Re: JDom and Java5

"Gregor Zeitlinger" <[email protected]>
Newsgroups gmane.comp.java.jdom.general
Message-ID <[email protected]>
On Sat, Feb 23, 2008 at 3:51 PM, Rolf <[email protected]> wrote:
>  As for Mattias's original claim that List<?> can be cast to
>  List<Element> if you know the content will be only Elements, then, I
>  believe that lends a certain weight to List<?>, but, is the same not
>  true for List<Object>?
Yes, all of the discussed variations can be cast, but not all are
equivalent (see below).

>  Does this make sense?
I think this is (yet another) design flaw of Java generics.

1) List: this is pre-generics legacy code
2) List<?>: this construct should have been disallowed, as it's
equivalent to List<? extends Object>
3) List<Object>: a list where objects can be read and written
4) List<? extends Object>: a list where can be read only

-- 
Gregor Zeitlinger
[email protected]
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