Enforce “equals” in an interface

Question

I have an interface and I want everyone who implements this interface to implements an overrridden \"equals\" method.

Is there a way to make sure that happens?

Answer 1

I've experimented with writing the required contract for equals in the JavaDoc. But the requirement that hashCode is consistent with equals results in a very complex contract for hashCode. So I gave up and created abstract base class with a final implementation of the two methods instead.