How to ensure the toString() method is reimplemented in class?

Question

Suppose I have an interface and many classes implementing that interface. I want to enforce the overriding of the default implementation of toString() in each of those classes (that is, if some classes do not override it, that should result in a compilation error).

Is it possible to achieve that? Declaring public abstract String toString();, with or without the @Override annotation, in the interface body, is legal, but does not have any effect.

Answer 1

Yup, kind of.

protected abstract String internToString();

and then

@Override
public String toString() {
 return internToString(); 
}

in your base class.