org.datanucleus.store.query

Class AbstractQueryResult

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList

org.datanucleus.store.query.AbstractQueryResult

All Implemented Interfaces:

Serializable, Iterable, Collection, List, QueryResult

Direct Known Subclasses:

CandidateIdsQueryResult

public abstract class AbstractQueryResult
extends AbstractList
implements QueryResult, Serializable

Abstract representation of a QueryResult. Provides default implementations of the majority of list methods that we aren't likely to be providing in a concrete query result. This class is used where your query implementation needs to return a wrapper to a List so that you can intercept calls and convert a row of the results into object(s), to avoid full instantiation at creation. Supports the following query extensions :-

• datanucleus.query.resultSizeMethod The method used to find the size of the result set.
• datanucleus.query.loadResultsAtCommit Whether to load all results when the connection is closing. Has no effect if caching is not used.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	closed Whether the results are close.
protected List<ManagedConnectionResourceListener>	connectionListeners List of listeners to notify when the query results are closed.
protected boolean	loadResultsAtCommit Whether to load any unread results at commit (when connection is closed).
protected static Localiser	LOCALISER Localiser for messages.
protected Query	query The Query object.
protected String	resultSizeMethod Method for getting the size of the results.
protected int	size size of the query results.

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

Constructors

Constructor and Description
AbstractQueryResult(Query query) Constructor of the result from a Query.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(int index, Object element) Method to add a result.
boolean	add(Object o) Method to add results.
boolean	addAll(int index, Collection c) Method to add results.
void	addConnectionListener(ManagedConnectionResourceListener listener) Method to register a listener to be notified when the query result is closing.
protected void	assertIsOpen() Internal method to throw an Exception if the ResultSet is open.
void	clear() Method to clear the results.
void	close() Method to close the results, meaning that they are inaccessible after this point.
protected abstract void	closeResults() Inform the query result that we are closing the results now.
protected abstract void	closingConnection() Inform the query result that the connection is being closed so perform any 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.
void	disconnect() Method to disconnect the results from the ExecutionContext, meaning that thereafter it just behaves like a List.
abstract boolean	equals(Object o) Equality operator for QueryResults.
abstract Object	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() Accessor for the hashcode of this object
int	indexOf(Object o) Method to check the index of a result.
boolean	isEmpty() Returns true if this collection contains no elements.
protected boolean	isOpen() Accessor whether the results are open.
abstract Iterator	iterator() Accessor for an iterator for the results.
int	lastIndexOf(Object o) Method to check the last index of a result.
abstract ListIterator	listIterator() Accessor for a list iterator for the results.
Object	remove(int index) Method to remove a result.
Object	set(int index, Object element) Method to set the position of a result.
int	size() Method to return the size of the result.
List	subList(int fromIndex, int toIndex) Method return a sub list of results.
Object[]	toArray() Method to return the results as an array.
Object[]	toArray(Object[] a) Method to return the results as an array.

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

LOCALISER

protected static final Localiser LOCALISER

Localiser for messages.

closed

protected boolean closed

Whether the results are close.

query

protected Query query

The Query object.

connectionListeners

protected List<ManagedConnectionResourceListener> connectionListeners

List of listeners to notify when the query results are closed.

size

protected int size

size of the query results. Is -1 until known.

resultSizeMethod

protected String resultSizeMethod

Method for getting the size of the results.

loadResultsAtCommit

protected boolean loadResultsAtCommit

Whether to load any unread results at commit (when connection is closed).

Constructor Detail

AbstractQueryResult

public AbstractQueryResult(Query query)

Constructor of the result from a Query.

Parameters:

query - The Query

Method Detail

disconnect

public void disconnect()

Method to disconnect the results from the ExecutionContext, meaning that thereafter it just behaves like a List. All remaining results are read in at this point (unless selected not to be).

Specified by:

disconnect in interface QueryResult

closingConnection

protected abstract void closingConnection()

Inform the query result that the connection is being closed so perform any operations now, or rest in peace.

closeResults

protected abstract void closeResults()

Inform the query result that we are closing the results now.

close

public void close()

Method to close the results, meaning that they are inaccessible after this point.

Specified by:

close in interface QueryResult

addConnectionListener

public void addConnectionListener(ManagedConnectionResourceListener listener)

Method to register a listener to be notified when the query result is closing.

Parameters:

listener - The listener

isOpen

protected boolean isOpen()

Accessor whether the results are open.

Returns:

Whether it is open.

assertIsOpen

protected void assertIsOpen()

Internal method to throw an Exception if the ResultSet is open.

add

public void add(int index,
       Object element)

Method to add a result. Unsupported.

Specified by:

add in interface List

Overrides:

add in class AbstractList

Parameters:

index - The position to add

element - The results to add

add

public boolean add(Object o)

Method to add results. Unsupported.

Specified by:

add in interface Collection

Specified by:

add in interface List

Overrides:

add in class AbstractList

Parameters:

o - The result to add

Returns:

true if added successfully

addAll

public boolean addAll(int index,
             Collection c)

Method to add results. Unsupported.

Specified by:

addAll in interface List

Overrides:

addAll in class AbstractList

Parameters:

index - The position to add

c - The results to add

Returns:

true if added successfully

clear

public void clear()

Method to clear the results.

Specified by:

clear in interface Collection

Specified by:

clear in interface List

Overrides:

clear in class AbstractList

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 AbstractCollection

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 AbstractCollection

Parameters:

c - The collection of objects

Returns:

Whether they are all contained here.

equals

public abstract 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

Overrides:

equals in class AbstractList

Parameters:

o - The object to compare against

Returns:

Whether they are equal

get

public abstract Object get(int index)

Method to retrieve a particular element from the list.

Specified by:

get in interface List

Specified by:

get in class AbstractList

Parameters:

index - The index of the element

Returns:

The element at index

hashCode

public int hashCode()

Accessor for the hashcode of this object

Specified by:

hashCode in interface Collection

Specified by:

hashCode in interface List

Overrides:

hashCode in class AbstractList

Returns:

The hash code

indexOf

public int indexOf(Object o)

Method to check the index of a result. Not supported.

Specified by:

indexOf in interface List

Overrides:

indexOf in class AbstractList

Parameters:

o - The result

Returns:

The position

isEmpty

public boolean isEmpty()

Returns true if this collection contains no elements.

Specified by:

isEmpty in interface Collection

Specified by:

isEmpty in interface List

Overrides:

isEmpty in class AbstractCollection

Returns:

true if this collection contains no elements.

iterator

public abstract 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

Overrides:

iterator in class AbstractList

Returns:

The iterator

lastIndexOf

public int lastIndexOf(Object o)

Method to check the last index of a result. Not supported.

Specified by:

lastIndexOf in interface List

Overrides:

lastIndexOf in class AbstractList

Parameters:

o - The result

Returns:

The last index

listIterator

public abstract ListIterator listIterator()

Accessor for a list iterator for the results.

Specified by:

listIterator in interface List

Overrides:

listIterator in class AbstractList

Returns:

a ListIterator with the query results

remove

public Object remove(int index)

Method to remove a result. Not supported.

Specified by:

remove in interface List

Overrides:

remove in class AbstractList

Parameters:

index - The position of the result.

Returns:

The removed object.

set

public Object set(int index,
         Object element)

Method to set the position of a result. Not supported.

Specified by:

set in interface List

Overrides:

set in class AbstractList

Parameters:

index - Position of the result

element - The result

Returns:

The element

size

public int size()

Method to return the size of the result. Hands off the calculation of the size to getSizeUsingMethod() which should be overridden if you want to support other methods.

Specified by:

size in interface Collection

Specified by:

size in interface List

Specified by:

size in class AbstractCollection

Returns:

The size of the result.

subList

public List subList(int fromIndex,
           int toIndex)

Method return a sub list of results. Method create new ArrayList, iterate and call get() in subclass for optimum performance.

Specified by:

subList in interface List

Overrides:

subList in class AbstractList

Parameters:

fromIndex - start position

toIndex - end position (exclusive)

Returns:

The list of results

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 AbstractCollection

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 AbstractCollection

Parameters:

a - The array to copy into.

Returns:

The array.

getSizeUsingMethod

protected int getSizeUsingMethod()

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

Returns:

The size