Package com.espertech.esper.common.internal.view.lastevent

Class LastEventView

java.lang.Object
com.espertech.esper.common.internal.view.core.ViewSupport
com.espertech.esper.common.internal.view.lastevent.LastEventView
All Implemented Interfaces:
DataWindowView, View, Viewable, ViewDataVisitable, Iterable<EventBean>
public class LastEventView extends ViewSupport implements DataWindowView
This view is a very simple view presenting the last event posted by the parent view to any subviews. Only the very last event object is kept by this view. The update method invoked by the parent view supplies new data in an object array, of which the view keeps the very last instance as the 'last' or newest event. The view always has the same schema as the parent view and attaches to anything, and accepts no parameters.

Thus if 5 pieces of new data arrive, the child view receives 5 elements of new data and also 4 pieces of old data which is the first 4 elements of new data. I.e. New data elements immediatly gets to be old data elements.

Old data received from parent is not handled, it is ignored. We thus post old data as follows: last event is not null + new data from index zero to N-1, where N is the index of the last element in new data

  • Field Details

    • lastEvent

      protected EventBean lastEvent
      The last new element posted from a parent view.

  • Constructor Details

  • Method Details

    • getEventType

      public final EventType getEventType()
      Description copied from interface: Viewable
      Provides metadata information about the type of object the event collection contains.
      Specified by:
      getEventType in interface Viewable
      Returns:
      metadata for the objects in the collection

    • update

      public void update(EventBean[] newData, EventBean[] oldData)
      Description copied from interface: View
      Notify that data has been added or removed from the Viewable parent. The last object in the newData array of objects would be the newest object added to the parent view. The first object of the oldData array of objects would be the oldest object removed from the parent view.

      If the call to update contains new (inserted) data, then the first argument will be a non-empty list and the second will be empty. Similarly, if the call is a notification of deleted data, then the first argument will be empty and the second will be non-empty. Either the newData or oldData will be non-null. This method won't be called with both arguments being null, but either one could be null. The same is true for zero-length arrays. Either newData or oldData will be non-empty. If both are non-empty, then the update is a modification notification.

      When update() is called on a view by the parent object, the data in newData will be in the collection of the parent, and its data structures will be arranged to reflect that. The data in oldData will not be in the parent's data structures, and any access to the parent will indicate that that data is no longer there.

      Specified by:
      update in interface View
      Parameters:
      newData - is the new data that has been added to the parent view
      oldData - is the old data that has been removed from the parent view

    • iterator

      public final Iterator<EventBean> iterator()
      Description copied from interface: Viewable
      Allows iteration through all elements in this viewable. The iterator will return the elements in the collection in their natural order, or, if there is no natural ordering, in some unpredictable order.
      Specified by:
      iterator in interface Iterable<EventBean>
      Specified by:
      iterator in interface Viewable
      Returns:
      an iterator which will go through all current elements in the collection.

    • toString

      public final String toString()
      Overrides:
      toString in class Object

    • visitView

      public void visitView(ViewDataVisitor viewDataVisitor)
      Specified by:
      visitView in interface ViewDataVisitable

    • getViewFactory

      public ViewFactory getViewFactory()