You're still casting. You're just postponing it a little.
DefaultServiceManager.lookup does a cast to type T. You specified what type
T is in MyClass.main. It is perhaps possible that DefaultServiceManager
could be implemented without casting (using further generics), but off the
top of my head I can't see how.
<snip>
interface ServiceManager {
public <T> T lookup (String key) throws Exception;
public void release (Object o);
}
class DefaultServiceManager implements ServiceManager {
public <T> T lookup (String key) throws Exception {
Object o = doGet (key);
try {
return (T) o; // unchecked cast to type T here, should be
fine.
} catch (Throwable t) {
return null;
}
}
private Object doGet (String key) {
if (key.equals ("A")) return new A();
if (key.equals ("B")) return new B();
return null;
}
public void release (Object o) {};
}
class A {}
class B {}
public class MyClass {
public static void main(String[] args) throws Exception {
ServiceManager sm = new DefaultServiceManager();
A a = sm.<A>lookup ("A");
B b = sm.<B>lookup ("B");
System.out.println (a);
System.out.println (b);
}
}
</snip>
----- Original Message -----
From: "Leo Sutic" <[EMAIL PROTECTED]>
To: "'Avalon Developers List'" <[EMAIL PROTECTED]>
Sent: Wednesday, January 28, 2004 11:18 AM
Subject: RE: Java 1.5, fun with lookups and generics
>
>
> > From: Jonathan Hawkes [mailto:[EMAIL PROTECTED]
> >
> > It just looks like a belayed cast to me.
>
> What do you mean by that?
>
> /LS
>
>
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