File APIs for Java Developers
Manipulate DOC, XLS, PPT, PDF and many others from your application.
http://aspose.com/file-tools
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic

Calling a Overriding method in a abstract class

 
Sivaraman Lakshmanan
Ranch Hand
Posts: 231
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
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
Posts: 231
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
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
Posts: 1780
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
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).
 
Shaan Shar
Ranch Hand
Posts: 1249
Java Spring Ubuntu
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
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
Ranch Hand
Posts: 1296
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
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.
 
Sivaraman Lakshmanan
Ranch Hand
Posts: 231
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
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
Posts: 22
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
You can do it as follows:



OR

 
Layne Lund
Ranch Hand
Posts: 3061
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
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
 
Shrinivas Mujumdar
Ranch Hand
Posts: 328
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
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
 
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic