How can I instantiate an interface if implementation is not available?

Question

If I have the interface accessible from all modules, but implementation cannot be accessible, how can I instantiate this from other modules?

If I have 3 modules, one module is accessible to all which has my interface, and the other 2 modules have no access to each other. How can I instantiate this interface?

How to access an implementation without adding Maven dependency?

Answer 1

Add a factory class alongside the interface. This factory can either be instantiated easily or provide a static method such as public static StuffFactory getInstance() {

This factory is in charge of creating new instances of your interface. Example:

public Stuff newStuff() {
  return new StuffImpl();
}