Java: design interface to force implementations to override toString

Question

I\'m developing an SPI and would like to define a Reportable interface such that any implementations must override toString() to something that is

Answer 1

What I understand is that you want to create a set of classes which neatly give their string representations. So that when something like System.out.println(yourobject) is called it shows meaningful data.

You cannot force your subclasses to override toString. But you can do something like this.

abstract class MyBase
{
    abstract String getNiceString();
    @Override
    public String toString()
    {
        return getNiceString();
    }
}

Answer 2

No, you can't do this. I'd suggest you choose a different method name, e.g.

public interface Reportable
{
    String createReport();
}

That will force implementations to write an appropriate method. toString() is already somewhat vague in its intention - whether it's for debug representations, user-visible representations (at which point you need to ask yourself about locales etc). Adding another meaning doesn't seem like a good idea to me.