Class ForwardQueryResult<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

org.datanucleus.store.query.AbstractQueryResult<E>

org.datanucleus.store.rdbms.query.AbstractRDBMSQueryResult<E>

org.datanucleus.store.rdbms.query.ForwardQueryResult<E>

All Implemented Interfaces:

Serializable, Iterable<E>, Collection<E>, List<E>, SequencedCollection<E>, org.datanucleus.store.query.QueryResult<E>

public final class ForwardQueryResult<E>
extends AbstractRDBMSQueryResult<E>
implements Serializable

Lazy collection results from a Query with the ResultSet in a forward direction. In general the actual result elements are only loaded when accessed with the exception of non-transactional or optimistic contexts that load the elements at initialisation.

If the query had a range defined and this was not handled in the datastore query then this QueryResult will skip the unrequired records and just return the range requested.

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private class	ForwardQueryResult.QueryResultIterator	An Iterator results of a pm.query.execute().iterator()

Field Summary

Fields

Modifier and Type	Field	Description
private Collection<Object>	candidates	The candidate list restriction (optional).
protected boolean	moreResultSetRows	Whether there are still more rows to be processed in the ResultSet.
protected List<Object>	resultIds
protected List<E>	resultObjs	The Result Objects.

Fields inherited from class AbstractRDBMSQueryResult

applyRangeChecks, bulkLoadedMmds, bulkLoadedValueByMemberNumber, closeStatementWithResultSet, fp, rof, rs

Fields inherited from class org.datanucleus.store.query.AbstractQueryResult

api, closed, connectionListeners, loadResultsAtCommit, query, resultSizeMethod, size

Fields inherited from class AbstractList

modCount

Constructor Summary

Constructors

Constructor	Description
ForwardQueryResult(org.datanucleus.store.query.Query query, ResultObjectFactory<E> rof, ResultSet rs, org.datanucleus.FetchPlan fp, Collection<Object> candidates)	Constructor of the result from a Query.

Method Summary

Modifier and Type	Method	Description
private void	advanceToEndOfResultSet()	Internal method to advance to the end of the ResultSet, populating the resultObjs, and close the ResultSet when complete.
void	close()	Method to close the results, making the results unusable thereafter.
protected void	closeResults()	Internal method to close the ResultSet.
protected void	closingConnection()	Method called to inform the query result that the connection is being closed so perform any required operations now, or rest in peace.
boolean	contains(Object o)	Method to check if the specified object is contained in this result.
boolean	containsAll(Collection c)	Method to check if all of the specified objects are contained here.
boolean	equals(Object o)
E	get(int index)	Method to retrieve a particular element from the list.
protected int	getSizeUsingMethod()	Method to get the size using the "resultSizeMethod".
int	hashCode()
void	initialise()
boolean	isEmpty()	Accessor for whether there are any results.
Iterator<E>	iterator()	Accessor for an iterator for the results.
ListIterator<E>	listIterator()	Accessor for an iterator for the results.
protected E	nextResultSetElement()	Accessor for the next object from the ResultSet.
private void	processNumberOfResults(int number)	Method to advance through the results, processing the specified number of results.
Object[]	toArray()	Method to return the results as an array.
<T> T[]	toArray(T[] a)	Method to return the results as an array.
protected Object	writeReplace()	Handle serialisation by returning a java.util.ArrayList of all of the results for this query after disconnecting the query which has the consequence of enforcing the load of all objects.

Methods inherited from class AbstractRDBMSQueryResult

disconnect, registerMemberBulkResultSet, setCloseStatementWithResultSet

Methods inherited from class org.datanucleus.store.query.AbstractQueryResult

add, add, addAll, addConnectionListener, assertIsOpen, clear, indexOf, isOpen, lastIndexOf, remove, set, size, subList

Methods inherited from class AbstractList

listIterator, removeRange

Methods inherited from class AbstractCollection

addAll, remove, removeAll, retainAll, toString

Methods inherited from class Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface Collection

parallelStream, removeIf, stream, toArray

Methods inherited from interface Iterable

forEach

Methods inherited from interface List

addAll, addFirst, addLast, getFirst, getLast, remove, removeAll, removeFirst, removeLast, replaceAll, retainAll, reversed, sort, spliterator

Field Details

moreResultSetRows

protected boolean moreResultSetRows

Whether there are still more rows to be processed in the ResultSet.

resultObjs

protected List<E> resultObjs

The Result Objects.

resultIds

protected List<Object> resultIds

candidates

private Collection<Object> candidates

The candidate list restriction (optional).

Constructor Details

ForwardQueryResult

public ForwardQueryResult(org.datanucleus.store.query.Query query,
 ResultObjectFactory<E> rof,
 ResultSet rs,
 org.datanucleus.FetchPlan fp,
 Collection<Object> candidates)

Constructor of the result from a Query.

Parameters:

query - The Query

rof - The factory to retrieve results from

rs - The ResultSet from the Query Statement

fp - FetchPlan

candidates - Candidate elements

Method Details

initialise

public void initialise()
                throws SQLException

Specified by:

initialise in class AbstractRDBMSQueryResult<E>

Throws:

SQLException

processNumberOfResults

private void processNumberOfResults(int number)

Method to advance through the results, processing the specified number of results.

Parameters:

number - Number of results (-1 means process all)

advanceToEndOfResultSet

private void advanceToEndOfResultSet()

Internal method to advance to the end of the ResultSet, populating the resultObjs, and close the ResultSet when complete.

nextResultSetElement

protected E nextResultSetElement()

Accessor for the next object from the ResultSet.

Returns:

The next element from the ResultSet.

closeResults

protected void closeResults()

Internal method to close the ResultSet.

Overrides:

closeResults in class AbstractRDBMSQueryResult<E>

close

public void close()

Method to close the results, making the results unusable thereafter.

Specified by:

close in interface org.datanucleus.store.query.QueryResult<E>

Overrides:

close in class AbstractRDBMSQueryResult<E>

closingConnection

protected void closingConnection()

Method called to inform the query result that the connection is being closed so perform any required operations now, or rest in peace.

Specified by:

closingConnection in class org.datanucleus.store.query.AbstractQueryResult<E>

iterator

public Iterator<E> iterator()

Accessor for an iterator for the results.

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface List<E>

Specified by:

iterator in class org.datanucleus.store.query.AbstractQueryResult<E>

Returns:

The iterator

listIterator

public ListIterator<E> listIterator()

Accessor for an iterator for the results.

Specified by:

listIterator in interface List<E>

Specified by:

listIterator in class org.datanucleus.store.query.AbstractQueryResult<E>

Returns:

The iterator

contains

public boolean contains(Object o)

Method to check if the specified object is contained in this result.

Specified by:

contains in interface Collection<E>

Specified by:

contains in interface List<E>

Overrides:

contains in class org.datanucleus.store.query.AbstractQueryResult<E>

Parameters:

o - The object

Returns:

Whether it is contained here.

containsAll

public boolean containsAll(Collection c)

Method to check if all of the specified objects are contained here.

Specified by:

containsAll in interface Collection<E>

Specified by:

containsAll in interface List<E>

Overrides:

containsAll in class org.datanucleus.store.query.AbstractQueryResult<E>

Parameters:

c - The collection of objects

Returns:

Whether they are all contained here.

equals

public boolean equals(Object o)

Specified by:

equals in interface Collection<E>

Specified by:

equals in interface List<E>

Overrides:

equals in class AbstractRDBMSQueryResult<E>

hashCode

public int hashCode()

Specified by:

hashCode in interface Collection<E>

Specified by:

hashCode in interface List<E>

Overrides:

hashCode in class AbstractRDBMSQueryResult<E>

get

public E get(int index)

Method to retrieve a particular element from the list.

Specified by:

get in interface List<E>

Specified by:

get in class org.datanucleus.store.query.AbstractQueryResult<E>

Parameters:

index - The index of the element

Returns:

The element at index

isEmpty

public boolean isEmpty()

Accessor for whether there are any results.

Specified by:

isEmpty in interface Collection<E>

Specified by:

isEmpty in interface List<E>

Overrides:

isEmpty in class org.datanucleus.store.query.AbstractQueryResult<E>

Returns:

true if these results are empty.

getSizeUsingMethod

protected int getSizeUsingMethod()

Method to get the size using the "resultSizeMethod". This implementation supports "LAST" method. Override this in subclasses to implement other methods.

Overrides:

getSizeUsingMethod in class org.datanucleus.store.query.AbstractQueryResult<E>

Returns:

The size

toArray

public Object[] toArray()

Method to return the results as an array.

Specified by:

toArray in interface Collection<E>

Specified by:

toArray in interface List<E>

Overrides:

toArray in class org.datanucleus.store.query.AbstractQueryResult<E>

Returns:

The array.

toArray

public <T> T[] toArray(T[] a)

Method to return the results as an array.

Specified by:

toArray in interface Collection<E>

Specified by:

toArray in interface List<E>

Overrides:

toArray in class org.datanucleus.store.query.AbstractQueryResult<E>

Parameters:

a - The array to copy into.

Returns:

The array.

writeReplace

protected Object writeReplace()
                       throws ObjectStreamException

Handle serialisation by returning a java.util.ArrayList of all of the results for this query after disconnecting the query which has the consequence of enforcing the load of all objects.

Returns:

The object to serialise

Throws:

ObjectStreamException - Thrown if an error occurs