I'm following this tutorial: http://wiki4.caucho.com/Building_a_simple_listing_in_JSP It creates a basic web application in Eclipse using the MVC pattern with Resin as the web container. Here's the part I don't understand.
For the model, it creates a POJO, Interface and Interface Implementation. The data represents a Book. When we get to the controller, it creates a simple servlet. It calls the interface instead of the interface implementation. How does the interface to execute the implementation class? Also what if there were two impl classes, how would the interface know which to call?