event_bus.rst

Event Bus

EventBus comes handy when you have a set of listeners that care about some events that happen in the background. Like an incoming message in a messenger app.

Events

An event can either consist of a single String or String + data Object. Events are posted using EventBus.postEvent(...) or EventBus.postEventSticky(...). Posting an event sticky means that it's most recent version will be delivered to newly registered receivers.

Events are guaranteed to be delivered on the main thread.

Event Receivers

In an Activity that extends base DroidParts Activities, the simplest way to register for Events is to use annotated methods:

@ReceiveEvents(name = { "MESSAGE_SENT", "MESSAGE_RECEIVED" })
private void onMessageEvent(String eventName) {
   // TODO process 2 kinds of events without data
}

@ReceiveEvents
private void onAnyEvent(String eventName, Object eventData) {
   // TODO process any event with optional data
}

You can also register arbitrary EventReceivers with EventBus.registerReceiver(...). And don't forget to call EventBus.unregisterReceiver(...).