How do I get a class instance of generic type T?

Question

I have a generics class, Foo<T>. In a method of Foo, I want to get the class instance of type T, but I just can't call T.class.

What is the preferred way to get around it using T.class?

Answer 1

The short answer is, that there is no way to find out the runtime type of generic type parameters in Java. I suggest reading the chapter about type erasure in the Java Tutorial for more details.

A popular solution to this is to pass the Class of the type parameter into the constructor of the generic type, e.g.

class Foo<T> {     final Class<T> typeParameterClass;      public Foo(Class<T> typeParameterClass) {         this.typeParameterClass = typeParameterClass;     }      public void bar() {         // you can access the typeParameterClass here and do whatever you like     } }