Class ActivityManager

java.lang.Object
com.google.gwt.activity.shared.ActivityManager
All Implemented Interfaces:
EventHandler, PlaceChangeEvent.Handler, PlaceChangeRequestEvent.Handler

public class ActivityManager extends Object implements PlaceChangeEvent.Handler, PlaceChangeRequestEvent.Handler
Manages Activity objects that should be kicked off in response to PlaceChangeEvent events. Each activity can start itself asynchronously, and provides a widget to be shown when it's ready to run.
  • Constructor Details

  • Method Details

    • getActiveEventBus

      public EventBus getActiveEventBus()
      Returns an event bus which is in use by the currently running activity.

      Any handlers attached to the returned event bus will be de-registered when the current activity is stopped.

      Returns:
      the event bus used by the current activity
    • onPlaceChange

      public void onPlaceChange(PlaceChangeEvent event)
      Deactivate the current activity, find the next one from our ActivityMapper, and start it.

      The current activity's widget will be hidden immediately, which can cause flicker if the next activity provides its widget asynchronously. That can be minimized by decent caching. Perenially slow activities might mitigate this by providing a widget immediately, with some kind of "loading" treatment.

      Specified by:
      onPlaceChange in interface PlaceChangeEvent.Handler
      Parameters:
      event - the PlaceChangeEvent
    • onPlaceChangeRequest

      public void onPlaceChangeRequest(PlaceChangeRequestEvent event)
      Reject the place change if the current activity is not willing to stop.
      Specified by:
      onPlaceChangeRequest in interface PlaceChangeRequestEvent.Handler
      Parameters:
      event - the PlaceChangeRequestEvent
      See Also:
    • setDisplay

      public void setDisplay(AcceptsOneWidget display)
      Sets the display for the receiver, and has the side effect of starting or stopping its monitoring the event bus for place change events.

      If you are disposing of an ActivityManager, it is important to call setDisplay(null) to get it to deregister from the event bus, so that it can be garbage collected.

      Parameters:
      display - an instance of AcceptsOneWidget