Package org.greenrobot.eventbus

Class EventBus

  • public class EventBus
extends java.lang.Object
    EventBus is a central publish/subscribe event system for Java and Android. Events are posted (post(Object)) to the bus, which delivers it to subscribers that have a matching handler method for the event type. To receive events, subscribers must register themselves to the bus using register(Object). Once registered, subscribers receive events until unregister(Object) is called. Event handling methods must be annotated by Subscribe, must be public, return nothing (void), and have exactly one parameter (the event).

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static java.lang.String TAG
      Log tag, apps may override it.

    • Constructor Summary

      Constructors 
      Constructor Description
      EventBus()
      Creates a new EventBus instance; each instance is a separate scope in which events are delivered.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static EventBusBuilder builder()  
      void cancelEventDelivery​(java.lang.Object event)
      Called from a subscriber's event handling method, further event delivery will be canceled.
      static void clearCaches()
      For unit test primarily.
      static EventBus getDefault()
      Convenience singleton for apps using a process-wide EventBus instance.
      Logger getLogger()
      For internal use only.
      <T> T getStickyEvent​(java.lang.Class<T> eventType)
      Gets the most recent sticky event for the given type.
      boolean hasSubscriberForEvent​(java.lang.Class<?> eventClass)  
      boolean isRegistered​(java.lang.Object subscriber)  
      void post​(java.lang.Object event)
      Posts the given event to the event bus.
      void postSticky​(java.lang.Object event)
      Posts the given event to the event bus and holds on to the event (because it is sticky).
      void register​(java.lang.Object subscriber)
      Registers the given subscriber to receive events.
      void removeAllStickyEvents()
      Removes all sticky events.
      <T> T removeStickyEvent​(java.lang.Class<T> eventType)
      Remove and gets the recent sticky event for the given event type.
      boolean removeStickyEvent​(java.lang.Object event)
      Removes the sticky event if it equals to the given event.
      java.lang.String toString()  
      void unregister​(java.lang.Object subscriber)
      Unregisters the given subscriber from all event classes.

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • TAG

        public static java.lang.String TAG
        Log tag, apps may override it.

    • Constructor Detail

      • EventBus

        public EventBus()
        Creates a new EventBus instance; each instance is a separate scope in which events are delivered. To use a central bus, consider getDefault().

    • Method Detail

      • getDefault

        public static EventBus getDefault()
        Convenience singleton for apps using a process-wide EventBus instance.

      • clearCaches

        public static void clearCaches()
        For unit test primarily.

      • register

        public void register​(java.lang.Object subscriber)
        Registers the given subscriber to receive events. Subscribers must call unregister(Object) once they are no longer interested in receiving events.

        Subscribers have event handling methods that must be annotated by Subscribe. The Subscribe annotation also allows configuration like ThreadMode and priority.

      • isRegistered

        public boolean isRegistered​(java.lang.Object subscriber)

      • unregister

        public void unregister​(java.lang.Object subscriber)
        Unregisters the given subscriber from all event classes.

      • post

        public void post​(java.lang.Object event)
        Posts the given event to the event bus.

      • cancelEventDelivery

        public void cancelEventDelivery​(java.lang.Object event)
        Called from a subscriber's event handling method, further event delivery will be canceled. Subsequent subscribers won't receive the event. Events are usually canceled by higher priority subscribers (see Subscribe.priority()). Canceling is restricted to event handling methods running in posting thread ThreadMode.POSTING.

      • postSticky

        public void postSticky​(java.lang.Object event)
        Posts the given event to the event bus and holds on to the event (because it is sticky). The most recent sticky event of an event's type is kept in memory for future access by subscribers using Subscribe.sticky().

      • getStickyEvent

        public <T> T getStickyEvent​(java.lang.Class<T> eventType)
        Gets the most recent sticky event for the given type.
        See Also:
        postSticky(Object)

      • removeStickyEvent

        public <T> T removeStickyEvent​(java.lang.Class<T> eventType)
        Remove and gets the recent sticky event for the given event type.
        See Also:
        postSticky(Object)

      • removeStickyEvent

        public boolean removeStickyEvent​(java.lang.Object event)
        Removes the sticky event if it equals to the given event.
        Returns:
        true if the events matched and the sticky event was removed.

      • removeAllStickyEvents

        public void removeAllStickyEvents()
        Removes all sticky events.

      • hasSubscriberForEvent

        public boolean hasSubscriberForEvent​(java.lang.Class<?> eventClass)

      • getLogger

        public Logger getLogger()
        For internal use only.

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object