cloning interfaces in Java

Question

I have a problem in Java:

I have an interface:

public interface I extends Cloneable {

}

and an abstract class:

public abstract class AbstractClass {

    private I i;

    public I i() {
        return (I)(i).clone();
    }
}

but the usage of clone() yields the following error:

The method clone() is undefined for the type I

does anybody have any Idea how to get around this issue? the only fix I found is to add to I a new method: (I newI() ) that will clone I. is there a cleaner solution?

thanks.

score 7 · Accepted Answer · edited May 23 '17 at 12:30

7

You need to override the clone() method to be public

public interface MyI extends Cloneable {
    public MyI clone();
}

Rather bizarrely, Cloneable does not actually contain the clone() method and clone() is protected on Object! It's been discussed before on SO

edited May 23 '17 at 12:30

Community

1
1

answered Nov 20 '09 at 11:50

oxbow_lakes

133,303
56
317
449

so as I understand, there is no cleaner solution than re-defining clone() (or newI as I called it) in my Interface, because Interfaces do not inherit from Object. – Eyal Nov 20 '09 at 12:03
Yes - it's been my experience that a lot of people stay clear of `clone()` because it is so non-standard. – oxbow_lakes Nov 20 '09 at 15:36

score 2 · Answer 2 · answered Nov 20 '09 at 11:50

2

What would happen if you changed:

return (I)(i).clone();

to

return ((I)i).clone();

?

answered Nov 20 '09 at 11:50

Stuart

176
2

no need. i is of type I. and the outer cast is needed because clone returns an Object type – Eyal Nov 20 '09 at 12:04

cloning interfaces in Java

2 Answers2