Preference between Interface and Abstract (or Super) class method

Question

I have a question: In Java, I have a class Fresher, which extends Employee and implements an interface IFresher. Please refer the code below.

public interface IFresher {
        // Some other stuff
    public void takeCall();
}



public class Employee extends Human {
        // Some other stuff
    public abstract void takeCall()
       {
          // Some basic implementation
       }

}

class  Fresher extends Employee implements IFresher
{
        @Override
    public void takeCall() {

    }
}

Question: Which takeCall() method gets implemented in the Fresher sub class, is it from interface or the super class, What is order of hierarchy followed in such cases when there is a conflict between the super class and the interface?

possible duplicate of [When to use abstract class or interface?](http://stackoverflow.com/questions/1221512/when-to-use-abstract-class-or-interface) — Jonathon Reinhart, Aug 03 '12 at 02:31
I know the I is not needed, but just to follow one naming convention :) — Astak Qes, Aug 03 '12 at 06:05
possible duplicate of [Java abstract class and interface](http://stackoverflow.com/questions/5094825/java-abstract-class-and-interface) — Sean Reilly, Aug 03 '12 at 12:00

score 2 · Accepted Answer · answered Aug 03 '12 at 02:30

There is never any conflict in this case - since interfaces don't contain implementations, there can only ever be one (superclass) implementation to inherit from.

Fresher will inherit implementation from Employee (in this case overriding the takeCall method). But it will also successfully implement IFresher as it has a function with the correct signature.

(Aside: this is the main reason why multiple implementation inheritance is disallowed in Java, it gets very tricky to define how it should all work)

Thanks for the answer and clarification, But as far as the Multiple Implementation inheritance is considered, Could you suggest a better design for the above case? — Astak Qes, Aug 03 '12 at 06:07

score 0 · Answer 2 · answered Aug 03 '12 at 02:29

0

In your case, Fresher takes precedence, specially since you are explicitly overriding.

Interfaces are not taken into account as they only provide contract for the function signature and no functionality.

answered Aug 03 '12 at 02:29

Edmon

4,752
4
32
42

Preference between Interface and Abstract (or Super) class method

2 Answers2