com.swirl

Class EventBus

java.lang.Object

com.swirl.EventBus

public class EventBus
extends java.lang.Object

The EventBus is the main communication backbone of the library. All of the managers and listeners connect to this bus to receive events from the other participants. It ensures that events are dispatched on the thread the receiver is expecting to run on. THere are two main threads (accessed through Executors) of note: the mainLoopExecutor and the swirl internal ScheduledServiceExecutor. All the managers run on the latter, user added listeners run on the former.

This system works by marking single parameter public methods with an @Subscribe annotation. The type of the single parameter must be unique. The events sent to the bus when posted are matched against all of the listeners and dispatches occur when and where there is a match.

This class is documented for those that desire to catch events directly using the @Subscribe annotation and for those who want to write managers that might post() events onto the bus.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	EventBus.Subscribe

Constructor Summary

Constructors

Constructor and Description
EventBus()

Method Summary

Modifier and Type	Method and Description
void	addListener(java.lang.Object listener, java.util.concurrent.Executor executor) Adds a listener to the bus provided it is not already a listener in which case this action does nothing.
java.lang.Object	findListener(java.lang.Class aclass) Find a listener on the bus of a given class.
long	getLastDispatchMillis() Get the timestamp of the last event dispatched.
void	post(java.lang.Object event) Post an event or object onto the bus.
void	removeListener(java.lang.Object listener) Remove a listener from the bus provided it is already a listener.
void	resume() Resume delivery of events.
void	suspend() Temporarily suspend event delivery.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

EventBus

public EventBus()

Method Detail

suspend

public void suspend()

Temporarily suspend event delivery. The EventBus starts in a suspended state. Events posted when the bus is suspended are queued for later delivery when delivery is resumed.

resume

public void resume()

Resume delivery of events. Any queued events are delivered at this time.

getLastDispatchMillis

public long getLastDispatchMillis()

Get the timestamp of the last event dispatched.

Returns:

addListener

public void addListener(java.lang.Object listener,
                        java.util.concurrent.Executor executor)

Adds a listener to the bus provided it is not already a listener in which case this action does nothing. All events that this listener has @Subscribed to will be executed on the Executor provided.

Parameters:

listener - The object that is listening for Events (or any class)

executor - The executor that is used to call those event handlers.

removeListener

public void removeListener(java.lang.Object listener)

Remove a listener from the bus provided it is already a listener.

Parameters:

listener - Listener to be removed.

findListener

public java.lang.Object findListener(java.lang.Class aclass)

Find a listener on the bus of a given class. Finds the first listener of a given class.

Parameters:

aclass - Class of the listener to find

Returns:

First instance of listener with aclass or null if none found

post

public void post(java.lang.Object event)

Post an event or object onto the bus. All listeners who implement public methods that have a single parameter with a matching class and an @Subscribe annotation will have those methods called.

Parameters:

event - The object to be dispatched.