org.openrdf.repository
Class RepositoryResult<T>

java.lang.Object
  info.aduna.iteration.CloseableIterationBase<E,X>
      info.aduna.iteration.IterationWrapper<T,RepositoryException>
          org.openrdf.repository.RepositoryResult<T>

All Implemented Interfaces:

CloseableIteration<T,RepositoryException>, Iteration<T,RepositoryException>

public class RepositoryResult<T>
extends IterationWrapper<T,RepositoryException>

A RepositoryResult is a result collection of objects (for example Statement, Namespace, or Resource objects) that can be iterated over. It keeps an open connection to the backend for lazy retrieval of individual results. Additionally it has some utility methods to fetch all results and add them to a collection.

By default, a RepositoryResult is not necessarily a (mathematical) set: it may contain duplicate objects. Duplicate filtering can be {switched on, but this should not be used lightly as the filtering mechanism is potentially memory-intensive.

A RepositoryResult needs to be closed after use to free up any resources (open connections, read locks, etc.) it has on the underlying repository.

Author:

jeen, Arjohn Kampman

See Also:

RepositoryConnection.getStatements(org.openrdf.model.Resource, org.openrdf.model.URI, org.openrdf.model.Value, boolean, org.openrdf.model.Resource[]), RepositoryConnection.getNamespaces(), RepositoryConnection.getContextIDs()

Field Summary

Fields inherited from class info.aduna.iteration.IterationWrapper

wrappedIter

Constructor Summary

RepositoryResult(CloseableIteration<? extends T,RepositoryException> iter)

Method Summary

<C extends Collection<T>> C	addTo(C collection) Adds all objects of this RepositoryResult to the supplied collection.
List<T>	asList() Returns a List containing all objects of this RepositoryResult in order of iteration.
void	enableDuplicateFilter() Switches on duplicate filtering while iterating over objects.

Methods inherited from class info.aduna.iteration.IterationWrapper

handleClose, 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, toString, wait, wait, wait

Constructor Detail

RepositoryResult

public RepositoryResult(CloseableIteration<? extends T,RepositoryException> iter)

Method Detail

enableDuplicateFilter

public void enableDuplicateFilter()
                           throws RepositoryException

Switches on duplicate filtering while iterating over objects. The RepositoryResult will keep track of the previously returned objects in a Set and on calling next() or hasNext() will ignore any objects that already occur in this Set.

Caution: use of this filtering mechanism is potentially memory-intensive.

Throws:

RepositoryException - if a problem occurred during initialization of the filter.

asList

public List<T> asList()
               throws RepositoryException

Returns a List containing all objects of this RepositoryResult in order of iteration. The RepositoryResult is fully consumed and automatically closed by this operation.

Note: use this method with caution! It pulls the entire RepositoryResult in memory and as such is potentially very memory-intensive.

Returns:

a List containing all objects of this RepositoryResult.

Throws:

RepositoryException - if a problem occurred during retrieval of the results.

See Also:

addTo(Collection)

addTo

public <C extends Collection<T>> C addTo(C collection)
                              throws RepositoryException

Adds all objects of this RepositoryResult to the supplied collection. The RepositoryResult is fully consumed and automatically closed by this operation.

Returns:

A reference to the collection that was supplied.

Throws:

RepositoryException - if a problem occurred during retrieval of the results.