question on subclass and superclass

[JayaSiji Gopal]

What will happen if you attempt to compile and run the following code?

 
class Base {}
class Sub extends Base {}
class Sub2 extends Base {}
public class CEx{
    public static void main(String argv[])
    {
        Base b=new Base();
        Sub s=(Sub) b;
    }
}

1) Compile and run without error
2) Compile time Exception
3) Runtime Exception

the correct answer is 3...i feel the correct answer is 1.

please explain...

(Unlike computers humans like to see neatly formatted code - BG)
[ November 03, 2004: Message edited by: Barry Gaunt ]

[Barry Gaunt]

And what does happen when you compile and run it? Ask yourself "is that object that b refers to really an instance of the Sub class?"
[ November 03, 2004: Message edited by: Barry Gaunt ]