During spring 2007 I was teaching the Java EE course in Shenkar college. It was delivered as part of Shenkar B.S.c. in software engineering. Part of it was devoted for Java ME in order to allow the students to develop a final project that includes a server side in Java EE and a client side which is a Java ME application for mobile telephones.
The Visitor Design Pattern
The visitor design pattern allows us to add operations to objects that already exist without modifying their classes and without extending them.