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

Question

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

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 {
    final Class typeParameterClass;

    public Foo(Class typeParameterClass) {
        this.typeParameterClass = typeParameterClass;
    }

    public void bar() {
        // you can access the typeParameterClass here and do whatever you like
    }
}