Is there a clean way to assign the Class of a generic type to a variable?

Question

Given this code:

List ints = new ArrayList();

// Type mismatch: 
// cannot convert from Class t         


        

Answer 1

This is a real Catch-22 in Java.

The compiler warns you if you don't add a generic type to List:

// WARN: List is not typed
Class typeTry3 = ints.getClass();

That's because, in most cases, it's really best to type your Lists.

However, because of type erasure, there's no way for Java to figure out the generic type of List at runtime, and the compiler knows that. Therefore, there is no method on Class that will returned a typed object:

// ERROR: ints.getClass() doesn't return a Class>, it returns a Class
Class> var = ints.getClass();

So you must cast it to a typed list. However, as you know, since there is no runtime type checking, Java warns you about any casts to a typed variable:

// WARN: Casting to typed List
Class> typeTry2 = (Class>) ints.getClass();

Any attempt to get around this is essentially a means of confusing the compiler, and will inevitably be convoluted.

Your best bet then is to go with Option B:

On the other hand, if warning suppression is the only way, what is the safest to suppress?

The safest way to suppress this warning is to make your @SuppressWarnings("unchecked") annotation as localized as possible. Put them above each individual unchecked cast. That way it's absolutely clear who's causing the warning.