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Q on abstract classes

Kedar Dravid
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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
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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.


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Getting someone to think and try something out is much more useful than just telling them the answer.
 
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subject: Q on abstract classes