Check the class name of the reference holding an object in Java

Question

class A {
}

class B extends A {
}

class TestType {
   public static void main(String args[]) {
      A a = new B();
      // I wish to use reference 'a' to check the Reference-Type which is 'A'.
   }
}

Is is possible? If no, then please specif the reason.

Answer 1

Chris Jester-Young's comment was excellent. It says:

You can't. The static type of local variables is not retained in the bytecode, nor at runtime. (If it's a field, you can use reflection on the field's containing class to get the field's type.)

See also What is the concept of erasure in generics in Java?

And http://gafter.blogspot.com/search?q=super+type+token.

Answer 2

Check the class name of the reference holding an object in Java

You can't.

1. There is no such thing as 'the reference holding an object. There could be zero such references, or there could be sixten gazillion of them.

2. You can't get it/them from inside the object being held.