How to do `MyClass.class` in Java?

Question

How can call public T doit(Class clazz); using MyClass.class as clazz where I can not instantiate or extend MyClas

Answer 1

How to do MyClass.class in Java?

You can't.

Generics in Java use type erasure; the type of the parametrized argument is enforced during compilation, but it is lost after compilation. The resulting byte code for an instance of a generic class does not contain any run-time meta-data on its arguments whatsoever.

As it is now, it is just not possible, a major language design blunder IMO.