Java Class Type

Question

I have a block of code that works and I wanted to ask what exactly is happening here?

Class<?> normalFormClass = null;

---added---

The wildcard "<?>" is the part that is confusing for me. Why would this be used rather than not using it (generics)?

Answer 1

That means it can be a Class of any type. ? is a wildcard denoting the set of all types, or 'any'. So you can later do

Integer normalForm = new Integer();
normalFormClass = normalForm.getClass();

or

String normalForm = new String();
normalFormClass = normalForm.getClass();

If you are not aware of generics on Java, read http://java.sun.com/developer/technicalArticles/J2SE/generics/

As for the why, I think it might be to strictly express that you are using generics everywhere and your code is not compatible with older Java versions, or maybe to shut up some trigger happy IDEs. And yes,

Class foo 

and

Class<?> foo 

are equivalent.

Answer 2

Also, the generic version

Class<?> normalClass = null;

is pretty much equivalent to the raw type version,

Class normalClass = null;

the main difference is that the latter will be compatible with versions of Java that do not support generics, like Java 1.4.