Package org.apache.cayenne.access.jdbc

Class DistinctResultIterator<T>

java.lang.Object

org.apache.cayenne.access.jdbc.DistinctResultIterator<T>

All Implemented Interfaces:

AutoCloseable, Iterable<T>, ResultIterator<T>

public class DistinctResultIterator<T>
extends Object
implements ResultIterator<T>

A ResultIterator that does in-memory filtering of rows to return only distinct rows. Distinct comparison is done by comparing ObjectIds created from each row. Internally DistinctResultIterator wraps another ResultIterator that provides the actual rows.

Since:

3.0

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	compareFullRows
protected DbEntity	defaultEntity
protected ResultIterator<T>	delegate
protected Set<Object>	fetchedIds
protected T	nextDataRow

Constructor Summary

Constructors

Constructor	Description
DistinctResultIterator(ResultIterator<T> delegate, DbEntity defaultEntity, boolean compareFullRows)	Creates new DistinctResultIterator wrapping another ResultIterator.

Method Summary

Modifier and Type	Method	Description
List<T>	allRows()	Returns all yet unread rows from ResultSet without closing it.
void	close()	Closes underlying ResultIterator.
boolean	hasNextRow()	Returns true if there is at least one more record that can be read from the iterator.
Iterator<T>	iterator()
T	nextRow()	Returns the next result row that is, depending on the query, may be a scalar value, a DataRow, or an Object[] array containing a mix of scalars and DataRows.
void	skipRow()	Goes past current row.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

delegate

protected ResultIterator<T> delegate

fetchedIds

protected Set<Object> fetchedIds

nextDataRow

protected T nextDataRow

defaultEntity

protected DbEntity defaultEntity

compareFullRows

protected boolean compareFullRows

Constructor Detail

DistinctResultIterator

public DistinctResultIterator(ResultIterator<T> delegate,
                              DbEntity defaultEntity,
                              boolean compareFullRows)

Creates new DistinctResultIterator wrapping another ResultIterator.

Parameters:

delegate - actual result iterator, that will be decorated by this DistinctResultIterator

defaultEntity - an entity needed to build ObjectIds for distinct comparison.

Method Detail

iterator

public Iterator<T> iterator()

Specified by:

iterator in interface Iterable<T>

Since:

4.0

close

public void close()

Closes underlying ResultIterator.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface ResultIterator<T>

allRows

public List<T> allRows()

Description copied from interface: ResultIterator

Returns all yet unread rows from ResultSet without closing it.

Specified by:

allRows in interface ResultIterator<T>

Since:

3.0

hasNextRow

public boolean hasNextRow()

Description copied from interface: ResultIterator

Returns true if there is at least one more record that can be read from the iterator.

Specified by:

hasNextRow in interface ResultIterator<T>

nextRow

public T nextRow()

Description copied from interface: ResultIterator

Returns the next result row that is, depending on the query, may be a scalar value, a DataRow, or an Object[] array containing a mix of scalars and DataRows.

Specified by:

nextRow in interface ResultIterator<T>

skipRow

public void skipRow()

Description copied from interface: ResultIterator

Goes past current row. If the row is not needed, this may save some time on data conversion.

Specified by:

skipRow in interface ResultIterator<T>

Since:

3.0