Qn from dan exam

[swetha shah]

class A {
void m1(A a) {System.out.print("A");}
}
class B extends A {
void m1(B b) {System.out.print("B");}
}
class C extends B {
void m1(C c) {System.out.print("C");}
}
class D {
public static void main(String[] args) {
A a1 = new A();
B b1 = new B();
C c1 = new C();
A c2 = new B();
c2.m1(a1);
c2.m1(b1);
c2.m1(c1);
}
}
In the above code result is "AAA".
I thought it would be "ABC" .
Though c2 is an object of A it is given a reference of C.So it should act as C object at runtime.Can anyone explain.

thanks
ss

[Rikko Verrijzer]

Please note, that the methods are overloaded not overridden. When you call the method with the object c2 of type A, m(A a) is called. since the other functions are added in the subclasses and are not known in the A class.
Hope this helps?
Rikko

[Anupam Sinha]

Hi Swetha
As Rikko said the methods are overloaded and notr overridden. When you call the methods on an instance of B. The B has inherited method m1() from its ancestors and they are executed and as C is subclass of B, m1() method of B can accept object of type C.
Swetha : Though c2 is an object of A it is given a reference of C.So it should act as C object at runtime.Can anyone explain.

c2 has been given a reference of B.
[ August 21, 2003: Message edited by: Anupam Sinha ]