Java实例化类的参数化类型

Question

Here's what I have:

class Class1 <T>
{
     public void foo()
   {
      ParameterizedType parameterizedType = (ParameterizedType)getClass().getGenericSuperclass();
      Class<T> type = (Class<T>) parameterizedType.getActualTypeArguments()[0];
      System.out.println(type);
   }
}

class Class2 <G>
{
    public Class2 ()
    {
        Class1<G> class1 = new Class1<G>();
    }
}

But when I call class1.foo(), I get the superclass and not the parameter.

If I do

Class1<String> class1 = new Class1<String>();

and then call class1.foo() inside Class1, I get String.

How can I fix to instantiate Class1 with the generic type of Class2?

Answer 1

You cannot. At runtime, Class2 doesn't know what its generic type argument is.