Method Overriding

[Srinivas Katta]

Hi All,

I was asked in an Interview

How to Override the Super class Method forcibly in sub class? mean to say is there any situation whre we must Override the method in sub class (Access visibility of the method is not an issue here)

Thanks
Srinivas

[Abimaran Kugathasan]

What about, if the super class is abstract?

[Srinivas Katta]

YeahI answered this but he did not agree with me. I feel if this situation can be really encountered in a Real time. I am not sure

[Abimaran Kugathasan]

Srinivas Katta wrote:YeahI answered this but he did not agree with me. I feel if this situation can be really encountered in a Real time. I am not sure

What are you talking about?

[Ernest Friedman-Hill]

Making the class abstract doesn't force you to override a method, but making a method abstract does -- at least, if you're trying to create a non-abstract, instantiable class.

[Abimaran Kugathasan]

Ernest Friedman-Hill wrote:Making the class abstract doesn't force you to override a method, but making a method abstract does -- at least, if you're trying to create a non-abstract, instantiable class.

Correct, I made a mistake there!

[Srinivas Katta]

Yes, That is true, Did you see any other situations for Forcibly overriding

Thanks a lot

[Abimaran Kugathasan]

Srinivas Katta wrote:Yes, That is true, Did you see any other situations for Forcibly overriding

What about implementing interface? But it's not a class.

[Dieter Quickfend]

what you could do, if you still want to instantiate that particular class, is set its accessibility to default, and extend two classes from it; A public final one, and a public abstract one that overrides the method you want overriden with an abstract method.

That way you ensure that no one outside the package can access your superclass, but it can Access the public final one that can't be subclassed, or it can access the public abstract one, which you can subclass, IF you override that method you want overriden.

[Prabhakar Reddy Bokka]

Dieter, i am confused

Confusing interviewer is fine.
But could you please clarify with sample code?

[Wouter Oet]

This is what Dieter is saying (I hope ):

package A;

class SuperClass {
	void toBeOverriden() {};
}
    

package A;

public final class PublicFinalSub extends SuperClass{
	@Override
	public void toBeOverriden() {
		System.out.println("Asdf");
	}
}    

package A;

public abstract class PublicAbstractSub extends SuperClass{
	@Override
	public abstract void toBeOverriden();
}    

[Prabhakar Reddy Bokka]

Yeah.. I understand.

But how does it makes difference in normal overriding functionality discussed above?
I dont find anything special, like child class must have to over ride.
It is again child class wish to over ride the method or declare abstract.

[Campbell Ritchie]

It's an interview question. Interview questions are designed to see how you handle problems, not to find out what your actual solutions are. The first response I would have made would be to ask what "forcibly" means.

[Wouter Oet]

The example I posted forces classes outside of package A to use the final version of the class or to extend the class and implement the method.