Package org.eclipse.rdf4j.common.iteration

Class FilterIteration<E>

java.lang.Object

org.eclipse.rdf4j.common.iteration.FilterIteration<E>

All Implemented Interfaces:

AutoCloseable, Iterator<E>, CloseableIteration<E>

Direct Known Subclasses:

DistinctIteration, FilteringIteration, FilterIterator, IntersectIteration, MinusIteration, OffsetIteration, ReducedIteration, SPARQLMinusIteration

public abstract class FilterIteration<E>
extends Object
implements CloseableIteration<E>

A CloseableIteration that wraps another Iteration, applying a filter on the objects that are returned. Subclasses must implement the accept method to indicate which objects should be returned.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	FilterIteration(CloseableIteration<? extends E> iter)

Method Summary

Modifier and Type	Method	Description
protected abstract boolean	accept(E object)	Tests whether or not the specified object should be returned by this Iteration.
final void	close()	Calls handleClose() upon first call and makes sure the resource closures are only executed once.
protected abstract void	handleClose()	Closes this Iteration and also closes the wrapped Iteration if it is a CloseableIteration.
boolean	hasNext()
E	next()
void	remove()	Removes the last element that has been returned from the wrapped Iteration.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eclipse.rdf4j.common.iteration.CloseableIteration

stream

Methods inherited from interface java.util.Iterator

forEachRemaining

Constructor Details

FilterIteration

protected FilterIteration(CloseableIteration<? extends E> iter)

Parameters:

iter -

Method Details

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator<E>

next

public E next()

Specified by:

next in interface Iterator<E>

accept

protected abstract boolean accept(E object)

Tests whether or not the specified object should be returned by this Iteration. All objects from the wrapped Iteration pass through this method in the same order as they are coming from the wrapped Iteration.

Parameters:

object - The object to be tested.

Returns:

true if the object should be returned, false otherwise.

remove

public void remove()

Removes the last element that has been returned from the wrapped Iteration.

Specified by:

remove in interface Iterator<E>

Throws:

UnsupportedOperationException - If the wrapped Iteration does not support the remove operation.

IllegalStateException - if the Iteration has been closed, or if next() has not yet been called, or remove() has already been called after the last call to next().

handleClose

protected abstract void handleClose()

Closes this Iteration and also closes the wrapped Iteration if it is a CloseableIteration.

close

public final void close()

Calls handleClose() upon first call and makes sure the resource closures are only executed once.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface CloseableIteration<E>