org.eclipse.rdf4j.common.iteration

Interface Iteration<E,X extends Exception>

Type Parameters:

E - Object type of objects contained in the iteration.

X - Exception type that is thrown when a problem occurs during iteration.

All Known Subinterfaces:

CloseableIteration<E,X>, GraphQueryResult, QueryResult<T>, TupleQueryResult

All Known Implementing Classes:

AbstractCloseableIteration, AbstractParserQuery.QueryInterruptIteration, AbstractParserQuery.QueryInterruptIteration, AlternativeCursor, BackgroundGraphResult, BackgroundGraphResult, BackgroundTupleResult, BackgroundTupleResult, BadlyDesignedLeftJoinIterator, BottomUpJoinIterator, BoundJoinConversionIteration, BoundJoinVALUESConversionIteration, CloseableIterationBase, CloseableIteratorIteration, CloseablePeakableIteration, CloseDependentConnectionIteration, CollectionIteration, CollectionIteration, CompatibleBindingSetFilter, ConsumingIteration, ControlledWorkerBoundJoin, ControlledWorkerJoin, ControlledWorkerLeftJoin, ControlledWorkerUnion, ConvertingIteration, CrossProductIteration, DelayedIteration, DescribeIteration, DistinctIteration, DistinctModelReducingUnionIteration, EmptyIteration, ExceptionConvertingIteration, ExtensionIterator, FedXQueueCursor, FilterCursor, FilteringInsertBindingsIteration, FilteringIteration, FilteringIteration, FilterIteration, FilterIterator, GraphQueryResultImpl, GraphToBindingSetConversionIteration, GroupedCheckConversionIteration, GroupIterator, HashJoin, HashJoinIteration, IndependentJoingroupBindingsIteration, IndependentJoingroupBindingsIteration2, IndependentJoingroupBindingsIteration3, InsertBindingSetCursor, InsertBindingSetCursor, InsertBindingsIteration, IntersectIteration, IteratingGraphQueryResult, IteratingTupleQueryResult, IterationWrapper, IteratorCloseableIteration, IteratorIteration, JoinExecutorBase, JoinExecutorBase, JoinExecutorBase, JoinIterator, LazyMutableClosableIteration, LeftJoinIterator, LimitedSizeBottomUpJoinIterator, LimitedSizeDistinctIteration, LimitedSizeHashJoinIteration, LimitedSizeIntersectIteration, LimitedSizeOrderIteration, LimitedSizePathIterator, LimitedSizeSPARQLMinusIteration, LimitedSizeZeroLengthPathIteration, LimitIteration, LockingIteration, LookAheadIteration, MemStatementIterator, MinusIteration, MultiProjectionIterator, MutableTupleQueryResult, OffsetIteration, OrderIterator, ParallelExecutorBase, ParallelJoinCursor, ParallelLeftJoinCursor, ParallelServiceExecutor, PathIteration, PrintingIteration, ProjectionIterator, QueryContextIteration, QueryResultIteration, QueueCursor, QueueCursor, QueueCursor, QueueCursor, QueueIteration, ReducedIteration, RepositoryExceptionConvertingIteration, RepositoryResult, ServiceCrossProductIteration, ServiceJoinConversionIteration, ServiceJoinConversionIteration, ServiceJoinIterator, SilentIteration, SilentIteration, SingleBindingSetIteration, SingletonIteration, SPARQLCrossProductIteration, SPARQLMinusIteration, StatementConversionIteration, StopRemainingExecutionsOnCloseIteration, SynchronousBoundJoin, SynchronousJoin, SynchronousWorkerUnion, TimeLimitIteration, TupleQueryResultImpl, UnionExecutorBase, UnionIteration, WorkerUnionBase, ZeroLengthPathIteration

public interface Iteration<E,X extends Exception>

An Iteration is a typed Iterator-like object that can throw (typed) Exceptions while iterating. This is used in cases where the iteration is lazy and evaluates over a (remote) connection, for example accessing a database. In such cases an error can occur at any time and needs to be communicated through a checked exception, something Iterator can not do (it can only throw RuntimeExceptions.

Author:

jeen, Herko ter Horst

See Also:

Iterator

Method Summary

Modifier and Type	Method and Description
boolean	hasNext() Returns true if the iteration has more elements.
E	next() Returns the next element in the iteration.
void	remove() Removes from the underlying collection the last element returned by the iteration (optional operation).
default java.util.stream.Stream<E>	stream() Convert the results to a Java 8 Stream.

Method Detail

hasNext

boolean hasNext()
         throws X extends Exception

Returns true if the iteration has more elements. (In other words, returns true if next() would return an element rather than throwing a NoSuchElementException.)

Returns:

true if the iteration has more elements.

Throws:

X

X extends Exception

next

E next()
throws X extends Exception

Returns the next element in the iteration.

Returns:

the next element in the iteration.

Throws:

NoSuchElementException - if the iteration has no more elements or if it has been closed.

X extends Exception

remove

void remove()
     throws X extends Exception

Removes from the underlying collection the last element returned by the iteration (optional operation). This method can be called only once per call to next.

Throws:

UnsupportedOperationException - if the remove operation is not supported by this Iteration.

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().

X extends Exception

stream

default java.util.stream.Stream<E> stream()

Convert the results to a Java 8 Stream. If this iteration implements CloseableIteration it should be closed (by calling Stream#close() or using try-with-resource) if it is not fully consumed.

Returns:

stream