You cannot require classes to implement particular static methods through an interface. It just makes no sense in Java terms. Interfaces force the presence of particular non-static methods in the classes that implement the interface; that’s what they do.
The easiest way is definitely to have some sort of factory class that produces instances of the others. Yes, this does mean that you have to remember to keep that factory up to date when you add new instances, but since the first thing you do when you make a new implementation is test it (you do test it, yes?) you’ll pick up on that problem very quickly!