How to get around the lack of abstract fields in Java?

Question

Assume, we have an abstract class A and we want to force all subclasses to have a certain field. This is not possible in Java, because we can not define abstrac

Answer 1

1. Actually its not about what one prefers but its about the flexibility, and the ability to adapt changes.

2. Its always better to Encapsulate Behaviors that keeps changing, either into an Interface or Abstract class.

3. You 1st Workaround will be good in places where you need different implementation for the same Behavior in Different classes. Then at this place either an Interface or your 1st Workaround will be a good choice.

Eg:

Consider Painting as a Class with paint() Method.

Now

paint() method can have Stroking, gliding, shading etc styles of doing it.

Then its better to Encapsulate that method into an Abstract class or an Interface.

public interface Paint{

paintDoIt(String style);

}

4. Your 2nd Wordaround will be good in a place, where you want certain behaviors to be MUST implemented by the Subclass.

Eg:

Consider Car as an Abstract Class, Now to be car its very important that it must have a Steering, 4 wheels, Engine, etc. So these features must be implemented.

where as other features like music system, LCD ,etc are optional and depends on the car type.