What makes an object assignment-compatible with another class?

Question

I\'m wondering what specifically allows an object of one class to be cast as another class. Looking at the Class.isInstance(Object obj) javadoc, it suggests that an object

Answer 1

Consider these two cases:

A a = new B();
B b = (B)a;    <--  Ok.

A a = new A();
B b = (B)a;    <--  ClassCastException

So in order to cast an object to B it must be an instance of B (or a subclass of B).

In your case it is however an instance of A.