Package org.eclipse.persistence.queries

Class ScrollableCursor

java.lang.Object

org.eclipse.persistence.queries.Cursor

org.eclipse.persistence.queries.ScrollableCursor

All Implemented Interfaces:

Serializable, Enumeration, Iterator, ListIterator

Direct Known Subclasses:

RemoteScrollableCursor

public class ScrollableCursor
extends Cursor
implements ListIterator

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	atEndOfCursor	Internal flag indicating if the end of the cursor has been reached
protected Object	nextObject
protected Object	previousObject
protected AbstractRecord	previousRow	Store the previous row, for 1-m joining.

Fields inherited from class org.eclipse.persistence.queries.Cursor

executionSession, fields, initiallyConformingIndex, nextRow, objectCollection, policy, position, query, resultSet, selectionCriteriaClone, session, size, statement, translationRow

Constructor Summary

Constructors

Constructor	Description
ScrollableCursor()	INTERNAL: Default constructor.
ScrollableCursor(DatabaseCall call, ScrollableCursorPolicy policy)	INTERNAL: constructor.

Method Summary

Modifier and Type	Method	Description
boolean	absolute(int rows)	PUBLIC: Moves the cursor to the given row number in the result set
void	add(Object object)	PUBLIC: Add is not support for scrollable cursors.
void	afterLast()	PUBLIC: Moves the cursor to the end of the result set, just after the last row.
void	beforeFirst()	PUBLIC: Moves the cursor to the front of the result set, just before the first row
protected void	clearNextAndPrevious()	INTERNAL: Clear the cached next and previous object and row values.
protected void	clearNextAndPreviousObject()	INTERNAL: Clear only the cached next and previous object values.
int	currentIndex()	PUBLIC: Retrieves the current row index number
boolean	first()	PUBLIC: Moves the cursor to the first row in the result set
protected int	getCursorSize()	INTERNAL: Retrieve the size of the open cursor by executing a count on the same query as the cursor.
protected int	getKnownCursorSize()
protected Object	getNextObject()
int	getPosition()	PUBLIC: Retrieves the current cursor position (current row).
protected Object	getPreviousObject()
boolean	hasMoreElements()	PUBLIC: Indicates whether the cursor can move to the the next row
boolean	hasNext()	PUBLIC: Indicates whether the cursor can move to the the next row
boolean	hasNextElement()	PUBLIC: Indicates whether the cursor can move to the the next row
boolean	hasPrevious()	PUBLIC: Indicates whether the cursor can move to the the previous row
boolean	isAfterLast()	PUBLIC: Indicates whether the cursor is after the last row in the result set.
boolean	isBeforeFirst()	PUBLIC: Indicates whether the cursor is before the first row in the result set.
boolean	isFirst()	PUBLIC: Indicates whether the cursor is on the first row of the result set.
boolean	isLast()	PUBLIC: Indicates whether the cursor is on the last row of the result set.
boolean	last()	PUBLIC: Moves the cursor to the last row in the result set
protected void	loadNext()	Load the next object
protected void	loadPrevious()	Load the previous object.
Object	next()	PUBLIC: This method differs slightly from conventional read() operation on a Java stream.
List<Object>	next(int number)	PUBLIC: This method differs slightly from conventional read() operation on a Java stream.
Object	nextElement()	PUBLIC: Return the next object from the collection, if beyond the read limit read from the cursor.
int	nextIndex()	PUBLIC: Retrieves the next row index (against the current row)
Object	previous()	PUBLIC: Return the previous object from the collection.
int	previousIndex()	PUBLIC: Retrieves the previous row index (against the current row)
boolean	relative(int rows)	PUBLIC: Moves the cursor a relative number of rows, either positive or negative.
protected Object	retrieveNextObject()	INTERNAL: Read the next row from the result set.
protected Object	retrievePreviousObject()	INTERNAL: CR#4139 Read the previous row from the result set.
void	set(Object object)	PUBLIC: Set is not supported for scrollable cursors.
protected void	setNextObject(Object nextObject)
protected void	setPreviousObject(Object previousObject)

Methods inherited from class org.eclipse.persistence.queries.Cursor

buildAndRegisterObject, clear, close, finalize, getAccessor, getExecutionSession, getFields, getInitiallyConformingIndex, getObjectCollection, getPageSize, getPolicy, getQuery, getResultSet, getSelectionCriteriaClone, getSession, getStatement, getTranslationRow, isClosed, remove, setExecutionSession, setFields, setInitiallyConformingIndex, setObjectCollection, setPolicy, setPosition, setResultSet, setSelectionCriteriaClone, setSession, setSize, setTranslationRow, size

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining

Methods inherited from interface java.util.ListIterator

remove

Field Detail

nextObject

protected transient Object nextObject

previousObject

protected transient Object previousObject

previousRow

protected AbstractRecord previousRow

Store the previous row, for 1-m joining.

atEndOfCursor

protected boolean atEndOfCursor

Internal flag indicating if the end of the cursor has been reached

Constructor Detail

ScrollableCursor

public ScrollableCursor()

INTERNAL: Default constructor.

ScrollableCursor

public ScrollableCursor(DatabaseCall call,
                        ScrollableCursorPolicy policy)

INTERNAL: constructor.

Method Detail

absolute

public boolean absolute(int rows)
                 throws DatabaseException

PUBLIC: Moves the cursor to the given row number in the result set

Throws:

DatabaseException

add

public void add(Object object)
         throws QueryException

PUBLIC: Add is not support for scrollable cursors.

Specified by:

add in interface ListIterator

Throws:

QueryException

afterLast

public void afterLast()
               throws DatabaseException

PUBLIC: Moves the cursor to the end of the result set, just after the last row.

Throws:

DatabaseException

beforeFirst

public void beforeFirst()
                 throws DatabaseException

PUBLIC: Moves the cursor to the front of the result set, just before the first row

Throws:

DatabaseException

clearNextAndPrevious

protected void clearNextAndPrevious()

INTERNAL: Clear the cached next and previous object and row values. This must be called whenever the cursor is re-positioned.

clearNextAndPreviousObject

protected void clearNextAndPreviousObject()

INTERNAL: Clear only the cached next and previous object values. Called by previous() and next() to maintain the cached next and previous row values.

currentIndex

public int currentIndex()
                 throws DatabaseException

PUBLIC: Retrieves the current row index number

Throws:

DatabaseException

first

public boolean first()
              throws DatabaseException

PUBLIC: Moves the cursor to the first row in the result set

Throws:

DatabaseException

getCursorSize

protected int getCursorSize()
                     throws DatabaseException

INTERNAL: Retrieve the size of the open cursor by executing a count on the same query as the cursor.

Specified by:

getCursorSize in class Cursor

Throws:

DatabaseException

getKnownCursorSize

protected int getKnownCursorSize()

getNextObject

protected Object getNextObject()

getPosition

public int getPosition()
                throws DatabaseException

PUBLIC: Retrieves the current cursor position (current row). The first row is number 1, the second number 2, and so on. Unlike java.sql.ResultSet.getRow(), 0 is not returned if afterLast. Instead size() + 1 is returned.

Specified by:

getPosition in class Cursor

Returns:

the current row number; 0 if there is no current row

Throws:

DatabaseException - if a database access error occurs

getPreviousObject

protected Object getPreviousObject()

hasMoreElements

public boolean hasMoreElements()
                        throws DatabaseException

PUBLIC: Indicates whether the cursor can move to the the next row

Specified by:

hasMoreElements in interface Enumeration

Throws:

DatabaseException

hasNext

public boolean hasNext()
                throws DatabaseException

PUBLIC: Indicates whether the cursor can move to the the next row

Specified by:

hasNext in interface Iterator

Specified by:

hasNext in interface ListIterator

Throws:

DatabaseException

hasNextElement

public boolean hasNextElement()
                       throws DatabaseException

PUBLIC: Indicates whether the cursor can move to the the next row

Throws:

DatabaseException

hasPrevious

public boolean hasPrevious()
                    throws DatabaseException

PUBLIC: Indicates whether the cursor can move to the the previous row

Specified by:

hasPrevious in interface ListIterator

Throws:

DatabaseException

isAfterLast

public boolean isAfterLast()
                    throws DatabaseException

PUBLIC: Indicates whether the cursor is after the last row in the result set.

Throws:

DatabaseException

isBeforeFirst

public boolean isBeforeFirst()
                      throws DatabaseException

PUBLIC: Indicates whether the cursor is before the first row in the result set.

Throws:

DatabaseException

isFirst

public boolean isFirst()
                throws DatabaseException

PUBLIC: Indicates whether the cursor is on the first row of the result set.

Throws:

DatabaseException

isLast

public boolean isLast()
               throws DatabaseException

PUBLIC: Indicates whether the cursor is on the last row of the result set.

Throws:

DatabaseException

last

public boolean last()
             throws DatabaseException

PUBLIC: Moves the cursor to the last row in the result set

Throws:

DatabaseException

loadNext

protected void loadNext()

Load the next object

loadPrevious

protected void loadPrevious()

Load the previous object. This is used solely for scrollable cursor support

next

public Object next()
            throws DatabaseException,
                   QueryException

PUBLIC: This method differs slightly from conventional read() operation on a Java stream. This method return the next object in the collection rather than specifying the number of bytes to be read in. Return the next object from the collection, if beyond the read limit read from the cursor

Specified by:

next in interface Iterator

Specified by:

next in interface ListIterator

Returns:

- next object in stream

Throws:

DatabaseException - if read pass end of stream

QueryException

next

public List<Object> next(int number)
                  throws DatabaseException

PUBLIC: This method differs slightly from conventional read() operation on a Java stream. This method returns the next number of objects in the collection in a vector. Return the next specified number of objects from the collection, if beyond the read limit read from the cursor

Parameters:

number - - number of objects to be returned

Returns:

- vector containing next number of objects

Throws:

DatabaseException - if read pass end of stream

nextElement

public Object nextElement()
                   throws DatabaseException,
                          QueryException

PUBLIC: Return the next object from the collection, if beyond the read limit read from the cursor.

Specified by:

nextElement in interface Enumeration

Returns:

next object in stream

Throws:

DatabaseException

QueryException

nextIndex

public int nextIndex()
              throws DatabaseException

PUBLIC: Retrieves the next row index (against the current row)

Specified by:

nextIndex in interface ListIterator

Throws:

DatabaseException

previous

public Object previous()
                throws DatabaseException,
                       QueryException

PUBLIC: Return the previous object from the collection.

Specified by:

previous in interface ListIterator

Returns:

- previous object in stream

Throws:

DatabaseException - if read pass first of stream

QueryException

previousIndex

public int previousIndex()
                  throws DatabaseException

PUBLIC: Retrieves the previous row index (against the current row)

Specified by:

previousIndex in interface ListIterator

Throws:

DatabaseException

relative

public boolean relative(int rows)
                 throws DatabaseException

PUBLIC: Moves the cursor a relative number of rows, either positive or negative. Attempting to move beyond the first/last row in the result set positions the cursor before/after the the first/last row

Throws:

DatabaseException

retrieveNextObject

protected Object retrieveNextObject()
                             throws DatabaseException

INTERNAL: Read the next row from the result set.

Specified by:

retrieveNextObject in class Cursor

Throws:

DatabaseException

retrievePreviousObject

protected Object retrievePreviousObject()
                                 throws DatabaseException

INTERNAL: CR#4139 Read the previous row from the result set. It is used solely for scrollable cursor support.

Throws:

DatabaseException

set

public void set(Object object)
         throws QueryException

PUBLIC: Set is not supported for scrollable cursors.

Specified by:

set in interface ListIterator

Throws:

QueryException

setNextObject

protected void setNextObject(Object nextObject)

setPreviousObject

protected void setPreviousObject(Object previousObject)