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Calling a Overriding method in a abstract class

Sivaraman Lakshmanan
Ranch Hand

Joined: Aug 02, 2003
Posts: 231
Hi all,
I have basic question which confused me. I am pasting the code below



Here the doit() method is overridden by class B. Now how do I access the doit() method of class A, from class B.

Thanks in Advance,

Regards,
Sivaraman.L
Sivaraman Lakshmanan
Ranch Hand

Joined: Aug 02, 2003
Posts: 231
Hi All,
In the previous post the class B code is wrong so I am posting it again.



Regards,
Sivaraman.L
Jeff Albertson
Ranch Hand

Joined: Sep 16, 2005
Posts: 1780
It's unclear what you intend this to mean: "Now how do I access the doit() method of class A, from class B."

1. Are you trying to invoke A's implementation of doit as a subroutine from within one of B's methods, say its version of doit? Use super:


2. Or are you confused why the following give the same results?

In both cases, B's implementation of doit is invoked because the object being passed the message "doit" is an instance of B (because you wrote new B() twice).


There is no emoticon for what I am feeling!
Shaan Shar
Ranch Hand

Joined: Dec 27, 2005
Posts: 1249

Actually What happen every time when you write such a code
e.g.

It will search automatically in Base Class first and if there present then execute that method otherwise it checks the method declaration in Derived Class. This is the way of Execution. So this is a known behaviour of JAVA. SO don't be surpriced too much.
.

Hope You will be understand this.

Garrett Rowe
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Joined: Jan 17, 2006
Posts: 1296
It will search automatically in Base Class first and if there present then execute that method otherwise it checks the method declaration in Derived Class...


Thats actually the opposite of what will happen.


Some problems are so complex that you have to be highly intelligent and well informed just to be undecided about them. - Laurence J. Peter
Sivaraman Lakshmanan
Ranch Hand

Joined: Aug 02, 2003
Posts: 231
Hi all,
Thanks for your replies. I want to call the A's doit() implementation from class B but not from any method in B, but from the B's main method.
something like...



Regards,
Sivaraman.L
Ajay A Patil
Greenhorn

Joined: Apr 13, 2006
Posts: 22
You can do it as follows:



OR

Layne Lund
Ranch Hand

Joined: Dec 06, 2001
Posts: 3061
Originally posted by Ajay A Patil:
You can do it as follows:



OR



This will not produce the results requested. Both examples will still call B's doit() method. In fact, I do not think there is any way to call A's doit() method from main unless you have an instance of A. An instance of B will always invoke B's doit() method, even if you have a reference to an A pointing to it.

Layne


Java API Documentation
The Java Tutorial
Shrinivas Mujumdar
Ranch Hand

Joined: Aug 27, 2004
Posts: 328
Yoy are right Layne,
You can call A's doit() either as a super.doit() in a method or with instance of A but in this case as A is abstract 2nd option is gone.

Shrinivas
 
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