Android - An Open Handset Alliance Project

android.database
public class

android.database.MergeCursor

java.lang.Object
	android.database.AbstractCursor		Cursor
		android.database.MergeCursor

A convience class that lets you present an array of Cursors as a single linear Cursor. The schema of the cursors presented is entirely up to the creator of the MergeCursor, and may be different if that is desired. Calls to getColumns, getColumnIndex, etc will return the value for the row that the MergeCursor is currently pointing at.

Summary

Fields inherited from class android.database.AbstractCursor

mContentResolver, mCurrentRowID, mPos, mRowIdColumnIndex, mUpdatedRows

Public Constructors

MergeCursor(Cursor[] cursors)

Public Methods

				int	count()
					Returns the numbers of rows in the cursor.
				void	deactivate()
					Deactivates the Cursor, making all calls on it fail until requery() is called.
				boolean	deleteRow()
					Removes the row at the current cursor position from the underlying data store.
				String[]	getColumnNames()
					Returns a string array holding the names of all of the columns in the result set in the order in which they were listed in the result.
				double	getDouble(int column)
					Returns the value of the requested column as a double.
				float	getFloat(int column)
					Returns the value of the requested column as a float.
				int	getInt(int column)
					Returns the value of the requested column as an int.
				long	getLong(int column)
					Returns the value of the requested column as a long.
				short	getShort(int column)
					Returns the value of the requested column as a short.
				String	getString(int column)
					Returns the value of the requested column as a String.
				boolean	isNull(int column)
					Returns `true` if the value in the indicated column is null.
				void	registerContentObserver(ContentObserver observer)
					Register an observer that is called when changes happen to the content backing this cursor.
				boolean	requery()
					Performs the query that created the cursor again, refreshing its contents.
				void	unregisterContentObserver(ContentObserver observer)
					Unregister an observer that has previously been registered with this cursor via registerContentObserver(ContentObserver).

Protected Methods

				boolean	onMove(int oldPosition, int newPosition)
					This function is called every time the cursor is successfully scrolled to a new position, giving the subclass a chance to update any state it may have.

Methods inherited from class android.database.AbstractCursor

abortUpdates, checkPosition, close, commitUpdates, commitUpdates, count, deactivate, deleteRow, finalize, first, getColumnIndex, getColumnName, getColumnNames, getDouble, getExtras, getFloat, getInt, getLong, getShort, getString, getUpdatedField, getWantsAllOnMoveCalls, hasUpdates, isAfterLast, isBeforeFirst, isFieldUpdated, isFirst, isLast, isNull, last, move, moveTo, next, onChange, onMove, position, prev, registerContentObserver, registerDataSetObserver, requery, respond, setNotificationUri, supportsUpdates, unregisterContentObserver, unregisterDataSetObserver, update, updateDouble, updateFloat, updateInt, updateLong, updateShort, updateString, updateToNull

		void	abortUpdates()
			Reverts all updates made to the cursor since the last call to commitUpdates.
		void	checkPosition()
			This function throws CursorIndexOutOfBoundsException if the cursor position is out of bounds.
		void	close()
			Closes the Cursor, releasing all of its resources and making it completely invalid.
		boolean	commitUpdates(Map values)
			Atomically commits all updates to the backing store, as well as the updates included in values.
		boolean	commitUpdates()
			Atomically commits all updates to the backing store.
abstract		int	count()
			Returns the numbers of rows in the cursor.
		void	deactivate()
			Deactivates the Cursor, making all calls on it fail until requery() is called.
		boolean	deleteRow()
			Removes the row at the current cursor position from the underlying data store.
		void	finalize()
			Called by the virtual machine when there are no longer any (non-weak) references to the receiver.
	final	boolean	first()
			Move the cursor to the first row.
		int	getColumnIndex(String columnName)
			Returns the zero-based index for the given column name.
		String	getColumnName(int columnIndex)
			Returns the column name at the given zero-based column index.
abstract		String[]	getColumnNames()
			Returns a string array holding the names of all of the columns in the result set in the order in which they were listed in the result.
abstract		double	getDouble(int column)
			Returns the value of the requested column as a double.
		Bundle	getExtras()
			Returns a bundle of extra values.
abstract		float	getFloat(int column)
			Returns the value of the requested column as a float.
abstract		int	getInt(int column)
			Returns the value of the requested column as an int.
abstract		long	getLong(int column)
			Returns the value of the requested column as a long.
abstract		short	getShort(int column)
			Returns the value of the requested column as a short.
abstract		String	getString(int column)
			Returns the value of the requested column as a String.
		Object	getUpdatedField(int columnIndex)
			This function returns the uncommitted updated value for the field at columnIndex.
		boolean	getWantsAllOnMoveCalls()
			onMove() will only be called across processes if this method returns true.
		boolean	hasUpdates()
			Returns `true` if there are pending updates that have not yet been committed.
	final	boolean	isAfterLast()
			Returns whether the cursor is pointing to the position after the last row.
	final	boolean	isBeforeFirst()
			Returns whether the cursor is pointing to the position before the first row.
		boolean	isFieldUpdated(int columnIndex)
			This function returns true if the field has been updated and is used in conjunction with getUpdatedField(int) to allow subclasses to support reading uncommitted updates.
	final	boolean	isFirst()
			Returns whether the cursor is pointing to the first row.
	final	boolean	isLast()
			Returns whether the cursor is pointing to the last row.
abstract		boolean	isNull(int column)
			Returns `true` if the value in the indicated column is null.
	final	boolean	last()
			Move the cursor to the last row.
	final	boolean	move(int offset)
			Move the cursor by a relative amount, forward or backward, from the current position.
	final	boolean	moveTo(int position)
			Move the cursor to an absolute position.
	final	boolean	next()
			Move the cursor to the next row.
		void	onChange(boolean selfChange)
			Subclasses must call this method when they finish committing updates to notify all observers.
		boolean	onMove(int oldPosition, int newPosition)
			This function is called every time the cursor is successfully scrolled to a new position, giving the subclass a chance to update any state it may have.
	final	int	position()
			Returns the current position of the cursor in the row set.
	final	boolean	prev()
			Move the cursor to the previous row.
		void	registerContentObserver(ContentObserver observer)
			Register an observer that is called when changes happen to the content backing this cursor.
		void	registerDataSetObserver(DataSetObserver observer)
			Register an observer that is called when changes happen to the contents of the this cursors data set, for example, when the data set is changed via requery(), deactivate(), or close().
		boolean	requery()
			Performs the query that created the cursor again, refreshing its contents.
		Bundle	respond(Bundle extras)
			This is an out-of-band way for the the user of a cursor to communicate with the cursor.
		void	setNotificationUri(ContentResolver cr, Uri notifyUri)
			Specifies a content URI to watch for changes.
		boolean	supportsUpdates()
			Returns `true` if the cursor supports updates.
		void	unregisterContentObserver(ContentObserver observer)
			Unregister an observer that has previously been registered with this cursor via registerContentObserver(ContentObserver).
		void	unregisterDataSetObserver(DataSetObserver observer)
			Unregister an observer that has previously been registered with this cursor via registerContentObserver(ContentObserver).
		boolean	update(int columnIndex, Object obj)
		boolean	updateDouble(int columnIndex, double value)
			Updates the value for the given column in the row the cursor is currently pointing at.
		boolean	updateFloat(int columnIndex, float value)
			Updates the value for the given column in the row the cursor is currently pointing at.
		boolean	updateInt(int columnIndex, int value)
			Updates the value for the given column in the row the cursor is currently pointing at.
		boolean	updateLong(int columnIndex, long value)
			Updates the value for the given column in the row the cursor is currently pointing at.
		boolean	updateShort(int columnIndex, short value)
			Updates the value for the given column in the row the cursor is currently pointing at.
		boolean	updateString(int columnIndex, String value)
			Updates the value for the given column in the row the cursor is currently pointing at.
		boolean	updateToNull(int columnIndex)
			Removes the value for the given column in the row the cursor is currently pointing at.

Methods inherited from class java.lang.Object

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

	Object	clone()
		Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
	boolean	equals(Object o)
		Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
	void	finalize()
		Called by the virtual machine when there are no longer any (non-weak) references to the receiver.
final	Class	getClass()
		Answers the unique instance of java.lang.Class which represents the class of the receiver.
	int	hashCode()
		Answers an integer hash code for the receiver.
final	void	notify()
		Causes one thread which is `wait` ing on the receiver to be made ready to run.
final	void	notifyAll()
		Causes all threads which are `wait` ing on the receiver to be made ready to run.
	String	toString()
		Answers a string containing a concise, human-readable description of the receiver.
final	void	wait(long time, int frac)
		Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by `notify` or `notifyAll`) or the expiration of the timeout.
final	void	wait(long time)
		Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by `notify` or `notifyAll`) or the expiration of the timeout.
final	void	wait()
		Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by `notify` or `notifyAll`).

Methods inherited from interface android.database.Cursor

				void	abortUpdates()
					Reverts all updates made to the cursor since the last call to commitUpdates.
				void	close()
					Closes the Cursor, releasing all of its resources and making it completely invalid.
				boolean	commitUpdates(Map values)
					Atomically commits all updates to the backing store, as well as the updates included in values.
				boolean	commitUpdates()
					Atomically commits all updates to the backing store.
				int	count()
					Returns the numbers of rows in the cursor.
				void	deactivate()
					Deactivates the Cursor, making all calls on it fail until requery() is called.
				boolean	deleteRow()
					Removes the row at the current cursor position from the underlying data store.
				boolean	first()
					Move the cursor to the first row.
				int	getColumnIndex(String columnName)
					Returns the zero-based index for the given column name.
				String	getColumnName(int columnIndex)
					Returns the column name at the given zero-based column index.
				String[]	getColumnNames()
					Returns a string array holding the names of all of the columns in the result set in the order in which they were listed in the result.
				double	getDouble(int columnIndex)
					Returns the value of the requested column as a double.
				Bundle	getExtras()
					Returns a bundle of extra values.
				float	getFloat(int columnIndex)
					Returns the value of the requested column as a float.
				int	getInt(int columnIndex)
					Returns the value of the requested column as an int.
				long	getLong(int columnIndex)
					Returns the value of the requested column as a long.
				short	getShort(int columnIndex)
					Returns the value of the requested column as a short.
				String	getString(int columnIndex)
					Returns the value of the requested column as a String.
				boolean	getWantsAllOnMoveCalls()
					onMove() will only be called across processes if this method returns true.
				boolean	hasUpdates()
					Returns `true` if there are pending updates that have not yet been committed.
				boolean	isAfterLast()
					Returns whether the cursor is pointing to the position after the last row.
				boolean	isBeforeFirst()
					Returns whether the cursor is pointing to the position before the first row.
				boolean	isFirst()
					Returns whether the cursor is pointing to the first row.
				boolean	isLast()
					Returns whether the cursor is pointing to the last row.
				boolean	isNull(int columnIndex)
					Returns `true` if the value in the indicated column is null.
				boolean	last()
					Move the cursor to the last row.
				boolean	move(int offset)
					Move the cursor by a relative amount, forward or backward, from the current position.
				boolean	moveTo(int position)
					Move the cursor to an absolute position.
				boolean	next()
					Move the cursor to the next row.
				int	position()
					Returns the current position of the cursor in the row set.
				boolean	prev()
					Move the cursor to the previous row.
				void	registerContentObserver(ContentObserver observer)
					Register an observer that is called when changes happen to the content backing this cursor.
				void	registerDataSetObserver(DataSetObserver observer)
					Register an observer that is called when changes happen to the contents of the this cursors data set, for example, when the data set is changed via requery(), deactivate(), or close().
				boolean	requery()
					Performs the query that created the cursor again, refreshing its contents.
				Bundle	respond(Bundle extras)
					This is an out-of-band way for the the user of a cursor to communicate with the cursor.
				void	setNotificationUri(ContentResolver cr, Uri uri)
					Register to watch a content URI for changes.
				boolean	supportsUpdates()
					Returns `true` if the cursor supports updates.
				void	unregisterContentObserver(ContentObserver observer)
					Unregister an observer that has previously been registered with this cursor via registerContentObserver(ContentObserver).
				void	unregisterDataSetObserver(DataSetObserver observer)
					Unregister an observer that has previously been registered with this cursor via registerContentObserver(ContentObserver).
				boolean	updateDouble(int columnIndex, double value)
					Updates the value for the given column in the row the cursor is currently pointing at.
				boolean	updateFloat(int columnIndex, float value)
					Updates the value for the given column in the row the cursor is currently pointing at.
				boolean	updateInt(int columnIndex, int value)
					Updates the value for the given column in the row the cursor is currently pointing at.
				boolean	updateLong(int columnIndex, long value)
					Updates the value for the given column in the row the cursor is currently pointing at.
				boolean	updateShort(int columnIndex, short value)
					Updates the value for the given column in the row the cursor is currently pointing at.
				boolean	updateString(int columnIndex, String value)
					Updates the value for the given column in the row the cursor is currently pointing at.
				boolean	updateToNull(int columnIndex)
					Removes the value for the given column in the row the cursor is currently pointing at.

Details

Public Constructors

public MergeCursor(Cursor[] cursors)

Public Methods

public int count()

Returns the numbers of rows in the cursor.

public void deactivate()

Deactivates the Cursor, making all calls on it fail until requery() is called. Inactive Cursors use fewer resources than active Cursors. Calling requery() will make the cursor active again.

public boolean deleteRow()

Removes the row at the current cursor position from the underlying data store. After this method returns the cursor will be pointing to the row after the row that is deleted. This has the side effect of decrementing the result of count() by one.

public String[] getColumnNames()

Returns a string array holding the names of all of the columns in the result set in the order in which they were listed in the result.

public double getDouble(int column)

Returns the value of the requested column as a double.

If the native content of that column is not numeric the result will be the result of passing the column value to Double.valueOf(x).

public float getFloat(int column)

Returns the value of the requested column as a float.

If the native content of that column is not numeric the result will be the result of passing the column value to Float.valueOf(x).

public int getInt(int column)

Returns the value of the requested column as an int.

If the native content of that column is not numeric the result will be the result of passing the column value to Integer.valueOf(x).

public long getLong(int column)

Returns the value of the requested column as a long.

If the native content of that column is not numeric the result will be the result of passing the column value to Long.valueOf(x).

public short getShort(int column)

Returns the value of the requested column as a short.

If the native content of that column is not numeric the result will be the result of passing the column value to Short.valueOf(x).

public String getString(int column)

Returns the value of the requested column as a String.

If the native content of that column is not text the result will be the result of passing the column value to String.valueOf(x).

public boolean isNull(int column)

Returns true if the value in the indicated column is null.

public void registerContentObserver(ContentObserver observer)

Register an observer that is called when changes happen to the content backing this cursor. Typically the data set won't change until requery() is called.

public boolean requery()

Performs the query that created the cursor again, refreshing its contents. This may be done at any time, including after a call to deactivate().

public void unregisterContentObserver(ContentObserver observer)

Unregister an observer that has previously been registered with this cursor via registerContentObserver(ContentObserver).

Protected Methods

protected boolean onMove(int oldPosition, int newPosition)

This function is called every time the cursor is successfully scrolled to a new position, giving the subclass a chance to update any state it may have. If it returns false the move function will also do so and the cursor will scroll to the beforeFirst position.

Parameters

oldPosition	the position that we're moving from
newPosition	the position that we're moving to

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android.database.MergeCursor

Summary

Fields inherited from class android.database.AbstractCursor

Public Constructors

Public Methods

Protected Methods

Methods inherited from class android.database.AbstractCursor

Methods inherited from class java.lang.Object

Methods inherited from interface android.database.Cursor

Details

Public Constructors

public MergeCursor(Cursor[] cursors)

Public Methods

public int count()

public void deactivate()

public boolean deleteRow()

public String[] getColumnNames()

public double getDouble(int column)

public float getFloat(int column)

public int getInt(int column)

public long getLong(int column)

public short getShort(int column)

public String getString(int column)

public boolean isNull(int column)

public void registerContentObserver(ContentObserver observer)

public boolean requery()

public void unregisterContentObserver(ContentObserver observer)

Protected Methods

protected boolean onMove(int oldPosition, int newPosition)

Parameters

protected	ContentResolver	mContentResolver
protected	Long	mCurrentRowID
protected	int	mPos
protected	int	mRowIdColumnIndex	This must be set to the index of the row ID column by any subclass that wishes to support updates.
protected	HashMap	mUpdatedRows	This HashMap contains a mapping from Long rowIDs to another Map that maps from String column names to new values.


e.g. "intent" or "activity"