Re: Another generics limitation

"Mike Schilling" <>
Tue, 24 Oct 2006 05:10:40 GMT
"Daniel Dyer" <"You don't need it"> wrote in message

When using generics with multiple bounds, like this:

    private <T extends List & Serializable> void method(T t)
       // Do something.

It seems that this method is useless to me without knowing, in advance,
the concrete type of T. What I really want is to be able to cast to a
type intersection. For example:

   method((List & Serializable) myObject)

The actual object referenced by myObject must be of a type that implements
both List and Serializable for this to work. So I presume you're discussing
the case where the reference is not, but is some wider type (say, Object.)
And you're right; there's no way I know of to cast an Object to an
implementor of two interfaces. Logically, (List)(Serializable)myObject
should do it, but the compiler doesn't treat it that way.

On the other hand, in the world of generics, it's less likely than it used
to be that you'll need to cast an Object that way.

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