Question

Assuming the following class stub:

public class Foo<T> {   private Class<T> type;    public Foo<T> () {} } 

Can I store the generic type T into the field type in the constructor, without changing the constructor’s signature to ‘public Foo<T> (Class<T> type)‘?

If yes, how? If no, why?

‘type = T‘ doesn’t seem to work.

Answer 1

No – type erasure means that you have to provide something at execution time. You could provide either an instance of T or Class<T> but the class itself will just have every occurrence of T replaced with Object.

This kind of thing is one of the biggest disadvantages of Java’s generics vs those in .NET. (On the other hand, the variance story is stronger – if more confusing – in Java than in .NET.)