Java design pattern: multiple event sources and one event handler

Question

I want to implement a project in Java, where I have several sources of events (Threads). Such an event source performs a specific task and had to notify of a unique event handler (Class), and it needs to perform other tasks in accordance with the notification of event sources.

My question is: how to implement this desiqn appropriately in Java? Is there a design similar to this design?

Thanks in advance:).

Answer 1

I think you are looking for an Observer pattern. Java has some standard interfaces (java.util.Observer, java.util.Observable), although they are not of type; so you might think of your own if the domain seems to require it.

class MyThread implements Runnable { Observable observable; public MyThread(EventHandler observer) { observable = new Observable(); observable.addObserver(observer); } public void run() { while (!done()) { Object result = doStuff(); observable.notifyObservers(result); } } } // might have this be singleton class EventHandler implements Observer { public synchronized void update(Observable o, Object arg) { accomplishOtherTask(); } } 

Answer 2

I like the acting pattern. Each thread acts as an actor, performing one task. What you do is in line (yes), which will be processed by the next player.

I have no experience with Java frameworks. Consult Google.

Answer 3

In GWT, this is called an event bus . Or GWT. HandlerManager or GWTx. PropertyChangeSupport Recommended Google Recommendations. The latter is available in J2SE from version 1.4.2

Answer 4

Perhaps I do not understand your question, but I think that you do not need a design template, but something from java.util.concurrent .

A ThreadPoolExecutor?

Answer 5

The observed pattern has no views on threads. In the EventThread Template, the listener can indicate in which thread and when the event is being processed.

 public class MyObservableObject { ... void addListener(MyListener listener, Executor executor); } public interface MyListener { void onEvent(Object sender, Object event); } // Example obj.addListener( myListener, CURRENT_THREAD ); obj.addListener( myListener, myWorkQueue ); obj.addListener( myListener, AWT_EDT ); // or SWT_EDT obj.addListener( myListener, Executors.newSingleThreadScheduledExecutor() );