org.openrdf.sail.federation.evaluation

Class AlternativeCursor<E>

java.lang.Object

info.aduna.iteration.CloseableIterationBase<E,X>

info.aduna.iteration.LookAheadIteration<E,QueryEvaluationException>

org.openrdf.sail.federation.evaluation.AlternativeCursor<E>

All Implemented Interfaces:

CloseableIteration<E,QueryEvaluationException>, Iteration<E,QueryEvaluationException>

public class AlternativeCursor<E>
extends LookAheadIteration<E,QueryEvaluationException>

If the primary cursor is empty, use the alternative cursor.

Author:

James Leigh

Constructor Summary

Constructors

Constructor and Description
AlternativeCursor(CloseableIteration<? extends E,QueryEvaluationException> primary, CloseableIteration<? extends E,QueryEvaluationException> alternative)

Method Summary

Modifier and Type	Method and Description
E	getNextElement() Gets the next element.
void	handleClose() Called by CloseableIterationBase.close() when it is called for the first time.
String	toString()

Methods inherited from class info.aduna.iteration.LookAheadIteration

hasNext, next, remove

Methods inherited from class info.aduna.iteration.CloseableIterationBase

close, isClosed

Methods inherited from class java.lang.Object

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

Constructor Detail

AlternativeCursor

public AlternativeCursor(CloseableIteration<? extends E,QueryEvaluationException> primary,
                         CloseableIteration<? extends E,QueryEvaluationException> alternative)

Method Detail

handleClose

public void handleClose()
                 throws QueryEvaluationException

Description copied from class: CloseableIterationBase

Called by CloseableIterationBase.close() when it is called for the first time. This method is only called once on each iteration. By default, this method does nothing.

Overrides:

handleClose in class LookAheadIteration<E,QueryEvaluationException>

Throws:

QueryEvaluationException

getNextElement

public E getNextElement()
                 throws QueryEvaluationException

Description copied from class: LookAheadIteration

Gets the next element. Subclasses should implement this method so that it returns the next element.

Specified by:

getNextElement in class LookAheadIteration<E,QueryEvaluationException>

Returns:

The next element, or null if no more elements are available.

Throws:

QueryEvaluationException

toString

public String toString()

Overrides:

toString in class Object