com.espertech.esper.view.std

Class FirstElementView

java.lang.Object

com.espertech.esper.view.ViewSupport

com.espertech.esper.view.std.FirstElementView

All Implemented Interfaces:

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

public class FirstElementView
extends ViewSupport
implements CloneableView, DataWindowView

View retaining the very first event. Any subsequent events received are simply discarded and not entered into either insert or remove stream. Only the very first event received is entered into the remove stream.

The view thus never posts a remove stream unless explicitly deleted from when used with a named window.

Field Summary

Fields

Modifier and Type	Field and Description
protected EventBean	firstEvent

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

EMPTY_VIEW_ARRAY, parent

Constructor Summary

Constructors

Constructor and Description
FirstElementView(FirstElementViewFactory viewFactory)

Method Summary

Modifier and Type	Method and Description
View	cloneView() Duplicates the view.
EventType	getEventType() Provides metadata information about the type of object the event collection contains.
ViewFactory	getViewFactory()
Iterator<EventBean>	iterator() Allows iteration through all elements in this event collection.
void	setFirstEvent(EventBean firstEvent)
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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

firstEvent

protected EventBean firstEvent

Constructor Detail

FirstElementView

public FirstElementView(FirstElementViewFactory 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

Returns:

cloned view

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 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 Iterable<EventBean>

Returns:

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

toString

public final String toString()

Overrides:

toString in class Object

setFirstEvent

public void setFirstEvent(EventBean firstEvent)

visitView

public void visitView(ViewDataVisitor viewDataVisitor)

Specified by:

visitView in interface ViewDataVisitable

getViewFactory

public ViewFactory getViewFactory()

Specified by:

getViewFactory in interface GroupableView