org.datanucleus.store.rdbms.query
Class ForwardQueryResult

java.lang.Object
  java.util.AbstractCollection<E>
      java.util.AbstractList
          org.datanucleus.store.query.AbstractQueryResult
              org.datanucleus.store.rdbms.query.AbstractRDBMSQueryResult
                  org.datanucleus.store.rdbms.query.ForwardQueryResult

All Implemented Interfaces:

Serializable, Iterable, Collection, List, org.datanucleus.store.query.QueryResult

public final class ForwardQueryResult
extends AbstractRDBMSQueryResult
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

Field Summary

protected boolean	moreResultSetRows Whether there are still more rows to be processed in the ResultSet.
protected List	resultIds
protected List	resultObjs The Result Objects.

Fields inherited from class org.datanucleus.store.rdbms.query.AbstractRDBMSQueryResult

rof, rs

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

closed, connectionListeners, loadResultsAtCommit, LOCALISER, query, resultSizeMethod, size

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

ForwardQueryResult(org.datanucleus.store.query.Query query, org.datanucleus.store.query.ResultObjectFactory rof, ResultSet rs, Collection candidates)
Constructor of the result from a Query.

Method Summary

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) Equality operator for QueryResults.
Object	get(int index) Method to retrieve a particular element from the list.
protected int	getSizeUsingMethod() Method to get the size using the "resultSizeMethod".
boolean	isEmpty() Accessor for whether there are any results.
Iterator	iterator() Accessor for an iterator for the results.
ListIterator	listIterator() Accessor for an iterator for the results.
protected Object	nextResultSetElement() Accessor for the next object from the ResultSet.
Object[]	toArray() Method to return the results as an array.
Object[]	toArray(Object[] 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 org.datanucleus.store.rdbms.query.AbstractRDBMSQueryResult

disconnect, hashCode

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 java.util.AbstractList

listIterator, removeRange

Methods inherited from class java.util.AbstractCollection

addAll, remove, removeAll, retainAll, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

addAll, remove, removeAll, retainAll

Methods inherited from interface java.util.List

addAll, remove, removeAll, retainAll

Field Detail

moreResultSetRows

protected boolean moreResultSetRows

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

resultObjs

protected List resultObjs

The Result Objects.

resultIds

protected List resultIds

Constructor Detail

ForwardQueryResult

public ForwardQueryResult(org.datanucleus.store.query.Query query,
                          org.datanucleus.store.query.ResultObjectFactory rof,
                          ResultSet rs,
                          Collection candidates)
                   throws SQLException

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

candidates - Candidate elements

Throws:

SQLException - if can't read ResultSet

Method Detail

nextResultSetElement

protected Object 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

close

public void close()

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

Specified by:

close in interface org.datanucleus.store.query.QueryResult

Overrides:

close in class AbstractRDBMSQueryResult

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

iterator

public Iterator iterator()

Accessor for an iterator for the results.

Specified by:

iterator in interface Iterable

Specified by:

iterator in interface Collection

Specified by:

iterator in interface List

Specified by:

iterator in class org.datanucleus.store.query.AbstractQueryResult

Returns:

The iterator

listIterator

public ListIterator listIterator()

Accessor for an iterator for the results.

Specified by:

listIterator in interface List

Specified by:

listIterator in class org.datanucleus.store.query.AbstractQueryResult

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

Specified by:

contains in interface List

Overrides:

contains in class org.datanucleus.store.query.AbstractQueryResult

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

Specified by:

containsAll in interface List

Overrides:

containsAll in class org.datanucleus.store.query.AbstractQueryResult

Parameters:

c - The collection of objects

Returns:

Whether they are all contained here.

equals

public boolean equals(Object o)

Equality operator for QueryResults. Overrides the AbstractList implementation since that uses size() and iterator() and that would cause problems when closed.

Specified by:

equals in interface Collection

Specified by:

equals in interface List

Specified by:

equals in class org.datanucleus.store.query.AbstractQueryResult

Parameters:

o - The object to compare against

Returns:

Whether they are equal

get

public Object get(int index)

Method to retrieve a particular element from the list.

Specified by:

get in interface List

Specified by:

get in class org.datanucleus.store.query.AbstractQueryResult

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

Specified by:

isEmpty in interface List

Overrides:

isEmpty in class org.datanucleus.store.query.AbstractQueryResult

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

Returns:

The size

toArray

public Object[] toArray()

Method to return the results as an array.

Specified by:

toArray in interface Collection

Specified by:

toArray in interface List

Overrides:

toArray in class org.datanucleus.store.query.AbstractQueryResult

Returns:

The array.

toArray

public Object[] toArray(Object[] a)

Method to return the results as an array.

Specified by:

toArray in interface Collection

Specified by:

toArray in interface List

Overrides:

toArray in class org.datanucleus.store.query.AbstractQueryResult

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