EventBus

EventBus allows publish-subscribe-style communication between components without requiring the components to explicitly register with one another (and thus be aware of each other). It is designed exclusively to replace traditional Java in-process event distribution using explicit registration. It is not a general-purpose publish-subscribe system, nor is it intended for interprocess communication.

// Class is typically registered by the container.
class EventBusChangeRecorder {
  @Subscribe public void recordCustomerChange(ChangeEvent e) {
    recordChange(e.getChange());
  }
}
// somewhere during initialization
eventBus.register(new EventBusChangeRecorder());
// much later
public void changeCustomer()
  ChangeEvent event = getChangeEvent();
  eventBus.post(event);
}