File APIs for Java Developers
Manipulate DOC, XLS, PPT, PDF and many others from your application.
The moose likes Beginning Java and the fly likes Q on abstract classes Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login
JavaRanch » Java Forums » Java » Beginning Java
Bookmark "Q on abstract classes" Watch "Q on abstract classes" New topic

Q on abstract classes

Kedar Dravid
Ranch Hand

Joined: May 28, 2004
Posts: 333
Recently, at an interview, I was asked the following question:
"Of what use would be an abstract class which has only one non-abstract method?"

I couldn't quite figure out the answer to this one. Any pointers in this direction would be welcome.
Barry Gaunt
Ranch Hand

Joined: Aug 03, 2002
Posts: 7729
Here's my guess: Suppose the class in question was a class named A.
Suppose A extended another abstract class S, or implemented an interface I, but A did not provide an implementation for any methods in the superclass S or interface I, then the class A must be declared abstract. The fact that it provides a single non-abstract method is irrelevant, I think. On the other hand, a class A with no behaviour (methods) at all would be rather pointless.

Ask a Meaningful Question and HowToAskQuestionsOnJavaRanch
Getting someone to think and try something out is much more useful than just telling them the answer.
I agree. Here's the link:
subject: Q on abstract classes
It's not a secret anymore!