org.datanucleus.store.query

Class AbstractQueryResult<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

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

Type Parameters:

E - Type of "element" returned by this query result

All Implemented Interfaces:

Serializable, Iterable<E>, Collection<E>, List<E>, QueryResult<E>

Direct Known Subclasses:

CandidateIdsQueryResult

public abstract class AbstractQueryResult<E>
extends AbstractList<E>
implements QueryResult<E>, 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 ApiAdapter	api
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 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

Modifier and Type	Method and Description
boolean	add(E o) Method to add results.
void	add(int index, E element) Method to add a result.
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 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() 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<E>	iterator() Accessor for an iterator for the results.
int	lastIndexOf(Object o) Method to check the last index of a result.
abstract ListIterator<E>	listIterator() Accessor for a list iterator for the results.
E	remove(int index) Method to remove a result.
E	set(int index, E element) Method to set the position of a result.
int	size() Method to return the size of the result.
List<E>	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, parallelStream, remove, removeAll, removeIf, retainAll, spliterator, stream

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface java.util.List

addAll, remove, removeAll, replaceAll, retainAll, sort, spliterator

Field Detail

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.

api

protected ApiAdapter api

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<E>

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<E>

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.

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<E>

Specified by:

equals in interface List<E>

Overrides:

equals in class AbstractList<E>

Parameters:

o - The object to compare against

Returns:

Whether they are equal

get

public abstract 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 AbstractList<E>

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<E>

Specified by:

hashCode in interface List<E>

Overrides:

hashCode in class AbstractList<E>

Returns:

The hash code

iterator

public abstract Iterator<E> iterator()

Accessor for an iterator for the results.

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface List<E>

Overrides:

iterator in class AbstractList<E>

Returns:

The iterator

listIterator

public abstract ListIterator<E> listIterator()

Accessor for a list iterator for the results.

Specified by:

listIterator in interface List<E>

Overrides:

listIterator in class AbstractList<E>

Returns:

a ListIterator with the query results

isEmpty

public boolean isEmpty()

Returns true if this collection contains no elements.

Specified by:

isEmpty in interface Collection<E>

Specified by:

isEmpty in interface List<E>

Overrides:

isEmpty in class AbstractCollection<E>

Returns:

true if this collection contains no elements.

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<E>

Specified by:

size in interface List<E>

Specified by:

size in class AbstractCollection<E>

Returns:

The size of the result.

subList

public List<E> 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<E>

Overrides:

subList in class AbstractList<E>

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<E>

Specified by:

toArray in interface List<E>

Overrides:

toArray in class AbstractCollection<E>

Returns:

The array.

toArray

public Object[] toArray(Object[] 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 AbstractCollection<E>

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

add

public void add(int index,
                E element)

Method to add a result. Unsupported.

Specified by:

add in interface List<E>

Overrides:

add in class AbstractList<E>

Parameters:

index - The position to add

element - The results to add

add

public boolean add(E o)

Method to add results. Unsupported.

Specified by:

add in interface Collection<E>

Specified by:

add in interface List<E>

Overrides:

add in class AbstractList<E>

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<E>

Overrides:

addAll in class AbstractList<E>

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<E>

Specified by:

clear in interface List<E>

Overrides:

clear in class AbstractList<E>

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 AbstractCollection<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 AbstractCollection<E>

Parameters:

c - The collection of objects

Returns:

Whether they are all contained here.

indexOf

public int indexOf(Object o)

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

Specified by:

indexOf in interface List<E>

Overrides:

indexOf in class AbstractList<E>

Parameters:

o - The result

Returns:

The position

lastIndexOf

public int lastIndexOf(Object o)

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

Specified by:

lastIndexOf in interface List<E>

Overrides:

lastIndexOf in class AbstractList<E>

Parameters:

o - The result

Returns:

The last index

remove

public E remove(int index)

Method to remove a result. Not supported.

Specified by:

remove in interface List<E>

Overrides:

remove in class AbstractList<E>

Parameters:

index - The position of the result.

Returns:

The removed object.

set

public E set(int index,
             E element)

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

Specified by:

set in interface List<E>

Overrides:

set in class AbstractList<E>

Parameters:

index - Position of the result

element - The result

Returns:

The element