Java Reference
In-Depth Information
their own update() methods to handle specific situations. Figure 11.3 depicts
the class diagram that defines class EventProcess .
11.4.3
Implementation
Class EventProcess implements the abstract component that represents the
generic control module of a client
server architecture. Every concrete
control module must implement the run() method. The attachTo() method
can be invoked by the object itself or by an external object that holds a
reference to this object. Clients wait for an event and suspend their execu-
tion by invoking method waitEvent() . Servers notify their state transitions by
notifying events with method notifyObservers() .
-
package parking;
import java.util.Observable;
import java.util.Observer;
public class EventProcess extends Observable implements
Observer, Runnable{
String name; // the name of this EventProcess
Thread thread;
// the thread that executes the run() method
boolean alive # false ; // true when the thread is running
String observable # "";// the name of an observable object
String event # "";
// the event this object is waiting for
public EventProcess(String name) {
this .name # name;
}
// the invoker of attachTo() is an Observer; the parameter
// is an Observable; it adds this object to the list of
// observers of "process";
Observable
Runnable
Observer
EventProcess
String name
Thread thread
update()
notifyObservers()
waitEvent()
run()
Figure 11.3 The class diagram
 
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