If I specific a method which return a generic class,how can I do than I can specific the type of generic class dynamicly ? for example
try {
Class c =C
Generic syntax is good at compile-time only. None of the types in a generic class or method are available at runtime. This is called type erasure. So you cannot do what you want to do, at least not this way.
Depending on the original problem you are trying to solve, you may be able to use wildcards instead.