Why generics for the Class type?

[Josef Garvi]

Why does the Class type use Generics?

Or in other words - how am I supposed to use it?
I store certain Classes in hash tables, and then create dynamic instances
of objects according to the correct type at run-time. What "type of class"
should my Class variables be??

--
Josef Garvi

"Reversing desertification through drought tolerant trees"
http://www.eden-foundation.org/

new income - better environment - more food - less poverty

 

[John C. Bollinger]

Why does the Class type use Generics?

Or in other words - how am I supposed to use it?
I store certain Classes in hash tables, and then create dynamic
instances of objects according to the correct type at run-time. What
"type of class" should my Class variables be??

It depends, but some way around you're going to need to use a wildcard
type parameter. Class<?> will definitely work, but you may be able to
use something more specific. For instance, if you are storing only
Class objects for classes that implement Serializable, you could use
Class<? extends Serializable>. You may indeed want to do this sort of
thing to achieve type safety and dispense with casting when you create
instances:

Class<? extends Serializable> clazz;

[...]

Serializable ser = clazz.newInstance(); /* typesafe; no cast required */

 

[Josef Garvi]

It depends, but some way around you're going to need to use a wildcard
type parameter. Class<?> will definitely work, but you may be able to
use something more specific. For instance, if you are storing only
Class objects for classes that implement Serializable, you could use
Class<? extends Serializable>. You may indeed want to do this sort of
thing to achieve type safety and dispense with casting when you create
instances:

Class<? extends Serializable> clazz;

[...]

Serializable ser = clazz.newInstance(); /* typesafe; no cast required */

Thanks. That's how I wanted it to work!

--
Josef Garvi

"Reversing desertification through drought tolerant trees"
http://www.eden-foundation.org/

new income - better environment - more food - less poverty