IN THIS CHAPTER
In an object-based application, most objects are passive. A passive object just sits there waiting for one of its methods to be invoked. A passive object's
private member variables can only be changed by the code in its own methods, so its state remains constant until one of its methods is invoked. In a multithreaded environment like Java, threads can run within objects to make the objects active. Objects that are active make autonomous changes to themselves.
Sometimes in modeling a system, it becomes apparent that if some of the objects were active, the model would ...