Casting

[Veena Pointi]

[CODE}
class A{}
class B extends A implements E{}//line 1
class C extends A{}
class D extends B{}
interface E{}
public class Question07 {
public static void main(String[] args) {
A a = new D();//line 2
C c = new C();//line 3
E e = (E)a;//line 4
B b = (B)e;//line 5
}
}
[/CODE]
How come the above code compiles & runs fine.Shouldn't it give runtime error at line 4 ?coz class A does not implement interface E.
Veena

[Dave Vick]

Veena
The variable a is declared as a variable of type A, so it can refer to an object of type A or any of its subclasses. In this case it is refering to an object of type D, a D object is an A object becasue it extends B which in turn extends A. So a D object is a D object, is a B object and is a A object also. However, since class B implements interface E, a B object, and a D object by inheritance, is also an E object.
hope that explains it for you

[Veena Pointi]

I got it!
Actually after posting I noticed a is referring to D....I gotta be very careful while reading question....
Thanks
Veena