CODEWITHSUNDEEP
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Reputation: 235

multiple interfaces having same method that is finally implemented by class

In an interview there are two interfaces B and C each having the same method public m1() class A implements B and C , If class A has to implement method m1, the implemented method would be of which interface.

at that time i was also confused that which method would be called can you please advise 

public interface A {

public void show();
}

public interface B {

public void show();
}

public class Test implements A, B {

public static void main(String[] args) {

A a;
B b;
Test t = new Test();
a = t;
a.show();
b = t;
b.show();

}

Upvotes: 2

Views: 1543

Answers (2)

tim
tim

Reputation: 467

You will have to implement show in the Test class.

You will only be able to implement it once in the Test class.

Keep in mind, the interfaces cannot, by definition, provide a default implementation of show.

Therefore, when you instantiate the Test class, the show method will only have one implementation at run-time. It will be the same implementation even if the objects have 2 different parent interfaces.

Upvotes: 1

Thilo
Thilo

Reputation: 262474

In Java, both interfaces overlap and there is just one method. It is not possible to provide two separate implementations (or to choose which one you want). If the two interface method definitions have incompatible return types, the class cannot extend both interfaces at the same time.

So, both a.show() and b.show() will call the exact same method.

In C#, you can disambiguate.

Upvotes: 4

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