com.espertech.esper.view.std
Class LastElementView

java.lang.Object
  com.espertech.esper.view.ViewSupport
      com.espertech.esper.view.std.LastElementView

All Implemented Interfaces:

CloneableView, DataWindowView, EventCollection, GroupableView, View, Viewable, ViewDataVisitable, java.lang.Iterable<EventBean>

public class LastElementView
extends ViewSupport
implements CloneableView, 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 Summary

protected EventBean

lastEvent The last new element posted from a parent view.

Fields inherited from class com.espertech.esper.view.ViewSupport

EMPTY_VIEW_ARRAY, parent

Constructor Summary

LastElementView(LastElementViewFactory viewFactory)

Method Summary

View	cloneView() Duplicates the view.
EventType	getEventType() Provides metadata information about the type of object the event collection contains.
ViewFactory	getViewFactory()
java.util.Iterator<EventBean>	iterator() Allows iteration through all elements in this event collection.
java.lang.String	toString()
void	update(EventBean[] newData, EventBean[] oldData) Notify that data has been added or removed from the Viewable parent.
void	visitView(ViewDataVisitor viewDataVisitor)

Methods inherited from class com.espertech.esper.view.ViewSupport

addView, addView, dumpChildViews, dumpUpdateParams, dumpUpdateParams, findDescendent, findViewIndex, getParent, getViews, hasViews, removeAllViews, removeView, removeView, setParent, updateChildren, updateChildren

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.espertech.esper.view.View

getParent, setParent

Methods inherited from interface com.espertech.esper.view.Viewable

addView, getViews, hasViews, removeAllViews, removeView

Field Detail

lastEvent

protected EventBean lastEvent

The last new element posted from a parent view.

Constructor Detail

LastElementView

public LastElementView(LastElementViewFactory viewFactory)

Method Detail

cloneView

public View cloneView()

Description copied from interface: CloneableView

Duplicates the view.

Expected to return a same view in initialized state for grouping.

Specified by:

cloneView in interface CloneableView

getEventType

public final EventType getEventType()

Description copied from interface: EventCollection

Provides metadata information about the type of object the event collection contains.

Specified by:

getEventType in interface EventCollection

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 java.util.Iterator<EventBean> iterator()

Description copied from interface: EventCollection

Allows iteration through all elements in this event collection. 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 EventCollection

Specified by:

iterator in interface java.lang.Iterable<EventBean>

Returns:

an iterator which will go through all current elements in the collection.

toString

public final java.lang.String toString()

Overrides:

toString in class java.lang.Object

visitView

public void visitView(ViewDataVisitor viewDataVisitor)

Specified by:

visitView in interface ViewDataVisitable

getViewFactory

public ViewFactory getViewFactory()

Specified by:

getViewFactory in interface GroupableView