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Added in API level 1

AbstractCursor

public abstract class AbstractCursor
extends Object implements CrossProcessCursor

java.lang.Object
   ↳ android.database.AbstractCursor
Known Direct Subclasses
Known Indirect Subclasses


This is an abstract cursor class that handles a lot of the common code that all cursors need to deal with and is provided for convenience reasons.

Summary

Nested classes

class AbstractCursor.SelfContentObserver

Cursors use this class to track changes others make to their URI. 

Inherited constants

From interface android.database.Cursor

Fields

protected boolean mClosed

This field was deprecated in API level 23. Use isClosed() instead.

protected ContentResolver mContentResolver

This field was deprecated in API level 23. Do not use.

protected int mPos

This field was deprecated in API level 23. Use getPosition() instead.

Public constructors

AbstractCursor()

Public methods

void close()

Closes the Cursor, releasing all of its resources and making it completely invalid.

void copyStringToBuffer(int columnIndex, CharArrayBuffer buffer)

Retrieves the requested column text and stores it in the buffer provided.

void deactivate()

Deactivates the Cursor, making all calls on it fail until requery() is called.

void fillWindow(int position, CursorWindow window)

Copies cursor data into the window.

byte[] getBlob(int column)

Returns the value of the requested column as a byte array.

int getColumnCount()

Return total number of columns

int getColumnIndex(String columnName)

Returns the zero-based index for the given column name, or -1 if the column doesn't exist.

int getColumnIndexOrThrow(String columnName)

Returns the zero-based index for the given column name, or throws IllegalArgumentException if the column doesn't exist.

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 int getCount()

Returns the numbers of rows in the cursor.

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.

Uri getNotificationUri()

Return the URI at which notifications of changes in this Cursor's data will be delivered, as previously set by setNotificationUri(ContentResolver, Uri).

final int getPosition()

Returns the current position of the cursor in the row set.

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.

int getType(int column)

Returns data type of the given column's value.

boolean getWantsAllOnMoveCalls()

onMove() will only be called across processes if this method returns true.

CursorWindow getWindow()

If the cursor is backed by a CursorWindow, returns a pre-filled window with the contents of the cursor, otherwise null.

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 isClosed()

return true if the cursor is closed

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 move(int offset)

Move the cursor by a relative amount, forward or backward, from the current position.

final boolean moveToFirst()

Move the cursor to the first row.

final boolean moveToLast()

Move the cursor to the last row.

final boolean moveToNext()

Move the cursor to the next row.

final boolean moveToPosition(int position)

Move the cursor to an absolute position.

final boolean moveToPrevious()

Move the cursor to the previous row.

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.

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 setExtras(Bundle extras)

Sets a Bundle that will be returned by getExtras().

void setNotificationUri(ContentResolver cr, Uri notifyUri)

Specifies a content URI to watch for changes.

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).

Protected methods

void checkPosition()

This function throws CursorIndexOutOfBoundsException if the cursor position is out of bounds.

void finalize()

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.

Object getUpdatedField(int columnIndex)

This method was deprecated in API level 11. Always returns null since Cursors do not support updating rows

boolean isFieldUpdated(int columnIndex)

This method was deprecated in API level 11. Always returns false since Cursors do not support updating rows

void onChange(boolean selfChange)

Subclasses must call this method when they finish committing updates to notify all observers.

Inherited methods

From class java.lang.Object
From interface android.database.CrossProcessCursor
From interface android.database.Cursor
From interface java.io.Closeable
From interface java.lang.AutoCloseable

Fields

mClosed

Added in API level 1
boolean mClosed

This field was deprecated in API level 23.
Use isClosed() instead.

mContentResolver

Added in API level 1
ContentResolver mContentResolver

This field was deprecated in API level 23.
Do not use.

mPos

Added in API level 1
int mPos

This field was deprecated in API level 23.
Use getPosition() instead.

Public constructors

AbstractCursor

Added in API level 1
AbstractCursor ()

Public methods

close

Added in API level 1
void close ()

Closes the Cursor, releasing all of its resources and making it completely invalid. Unlike deactivate() a call to requery() will not make the Cursor valid again.

copyStringToBuffer

Added in API level 1
void copyStringToBuffer (int columnIndex, 
                CharArrayBuffer buffer)

Retrieves the requested column text and stores it in the buffer provided. If the buffer size is not sufficient, a new char buffer will be allocated and assigned to CharArrayBuffer.data

Parameters
columnIndex int: the zero-based index of the target column. if the target column is null, return buffer
buffer CharArrayBuffer: the buffer to copy the text into.

deactivate

Added in API level 1
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.

fillWindow

Added in API level 1
void fillWindow (int position, 
                CursorWindow window)

Copies cursor data into the window.

Clears the window and fills it with data beginning at the requested row position until all of the data in the cursor is exhausted or the window runs out of space.

The filled window uses the same row indices as the original cursor. For example, if you fill a window starting from row 5 from the cursor, you can query the contents of row 5 from the window just by asking it for row 5 because there is a direct correspondence between the row indices used by the cursor and the window.

The current position of the cursor, as returned by getPosition(), is not changed by this method.

Parameters
position int: The zero-based index of the first row to copy into the window.
window CursorWindow: The window to fill.

getBlob

Added in API level 1
byte[] getBlob (int column)

Returns the value of the requested column as a byte array.

The result and whether this method throws an exception when the column value is null or the column type is not a blob type is implementation-defined.

Parameters
column int: the zero-based index of the target column.
Returns
byte[] the value of that column as a byte array.

getColumnCount

Added in API level 1
int getColumnCount ()

Return total number of columns

Returns
int number of columns

getColumnIndex

Added in API level 1
int getColumnIndex (String columnName)

Returns the zero-based index for the given column name, or -1 if the column doesn't exist. If you expect the column to exist use getColumnIndexOrThrow(String) instead, which will make the error more clear.

Parameters
columnName String: the name of the target column.
Returns
int the zero-based column index for the given column name, or -1 if the column name does not exist.

getColumnIndexOrThrow

Added in API level 1
int getColumnIndexOrThrow (String columnName)

Returns the zero-based index for the given column name, or throws IllegalArgumentException if the column doesn't exist. If you're not sure if a column will exist or not use getColumnIndex(String) and check for -1, which is more efficient than catching the exceptions.

Parameters
columnName String: the name of the target column.
Returns
int the zero-based column index for the given column name

getColumnName

Added in API level 1
String getColumnName (int columnIndex)

Returns the column name at the given zero-based column index.

Parameters
columnIndex int: the zero-based index of the target column.
Returns
String the column name for the given column index.

getColumnNames

Added in API level 1
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.

Returns
String[] the names of the columns returned in this query.

getCount

Added in API level 1
int getCount ()

Returns the numbers of rows in the cursor.

Returns
int the number of rows in the cursor.

getDouble

Added in API level 1
double getDouble (int column)

Returns the value of the requested column as a double.

The result and whether this method throws an exception when the column value is null, the column type is not a floating-point type, or the floating-point value is not representable as a double value is implementation-defined.

Parameters
column int: the zero-based index of the target column.
Returns
double the value of that column as a double.

getExtras

Added in API level 1
Bundle getExtras ()

Returns a bundle of extra values. This is an optional way for cursors to provide out-of-band metadata to their users. One use of this is for reporting on the progress of network requests that are required to fetch data for the cursor.

These values may only change when requery is called.

Returns
Bundle cursor-defined values, or Bundle.EMPTY if there are no values. Never null.

getFloat

Added in API level 1
float getFloat (int column)

Returns the value of the requested column as a float.

The result and whether this method throws an exception when the column value is null, the column type is not a floating-point type, or the floating-point value is not representable as a float value is implementation-defined.

Parameters
column int: the zero-based index of the target column.
Returns
float the value of that column as a float.

getInt

Added in API level 1
int getInt (int column)

Returns the value of the requested column as an int.

The result and whether this method throws an exception when the column value is null, the column type is not an integral type, or the integer value is outside the range [Integer.MIN_VALUE, Integer.MAX_VALUE] is implementation-defined.

Parameters
column int: the zero-based index of the target column.
Returns
int the value of that column as an int.

getLong

Added in API level 1
long getLong (int column)

Returns the value of the requested column as a long.

The result and whether this method throws an exception when the column value is null, the column type is not an integral type, or the integer value is outside the range [Long.MIN_VALUE, Long.MAX_VALUE] is implementation-defined.

Parameters
column int: the zero-based index of the target column.
Returns
long the value of that column as a long.

getNotificationUri

Added in API level 11
Uri getNotificationUri ()

Return the URI at which notifications of changes in this Cursor's data will be delivered, as previously set by setNotificationUri(ContentResolver, Uri).

Returns
Uri Returns a URI that can be used with ContentResolver.registerContentObserver to find out about changes to this Cursor's data. May be null if no notification URI has been set.

getPosition

Added in API level 1
int getPosition ()

Returns the current position of the cursor in the row set. The value is zero-based. When the row set is first returned the cursor will be at positon -1, which is before the first row. After the last row is returned another call to next() will leave the cursor past the last entry, at a position of count().

Returns
int the current cursor position.

getShort

Added in API level 1
short getShort (int column)

Returns the value of the requested column as a short.

The result and whether this method throws an exception when the column value is null, the column type is not an integral type, or the integer value is outside the range [Short.MIN_VALUE, Short.MAX_VALUE] is implementation-defined.

Parameters
column int: the zero-based index of the target column.
Returns
short the value of that column as a short.

getString

Added in API level 1
String getString (int column)

Returns the value of the requested column as a String.

The result and whether this method throws an exception when the column value is null or the column type is not a string type is implementation-defined.

Parameters
column int: the zero-based index of the target column.
Returns
String the value of that column as a String.

getType

Added in API level 11
int getType (int column)

Returns data type of the given column's value. The preferred type of the column is returned but the data may be converted to other types as documented in the get-type methods such as getInt(int), getFloat(int) etc.

Returned column types are

Parameters
column int: the zero-based index of the target column.
Returns
int column value type

getWantsAllOnMoveCalls

Added in API level 1
boolean getWantsAllOnMoveCalls ()

onMove() will only be called across processes if this method returns true.

Returns
boolean whether all cursor movement should result in a call to onMove().

getWindow

Added in API level 1
CursorWindow getWindow ()

If the cursor is backed by a CursorWindow, returns a pre-filled window with the contents of the cursor, otherwise null.

Returns
CursorWindow The pre-filled window that backs this cursor, or null if none.

isAfterLast

Added in API level 1
boolean isAfterLast ()

Returns whether the cursor is pointing to the position after the last row.

Returns
boolean whether the cursor is after the last result.

isBeforeFirst

Added in API level 1
boolean isBeforeFirst ()

Returns whether the cursor is pointing to the position before the first row.

Returns
boolean whether the cursor is before the first result.

isClosed

Added in API level 1
boolean isClosed ()

return true if the cursor is closed

Returns
boolean true if the cursor is closed.

isFirst

Added in API level 1
boolean isFirst ()

Returns whether the cursor is pointing to the first row.

Returns
boolean whether the cursor is pointing at the first entry.

isLast

Added in API level 1
boolean isLast ()

Returns whether the cursor is pointing to the last row.

Returns
boolean whether the cursor is pointing at the last entry.

isNull

Added in API level 1
boolean isNull (int column)

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

Parameters
column int: the zero-based index of the target column.
Returns
boolean whether the column value is null.

move

Added in API level 1
boolean move (int offset)

Move the cursor by a relative amount, forward or backward, from the current position. Positive offsets move forwards, negative offsets move backwards. If the final position is outside of the bounds of the result set then the resultant position will be pinned to -1 or count() depending on whether the value is off the front or end of the set, respectively.

This method will return true if the requested destination was reachable, otherwise, it returns false. For example, if the cursor is at currently on the second entry in the result set and move(-5) is called, the position will be pinned at -1, and false will be returned.

Parameters
offset int: the offset to be applied from the current position.
Returns
boolean whether the requested move fully succeeded.

moveToFirst

Added in API level 1
boolean moveToFirst ()

Move the cursor to the first row.

This method will return false if the cursor is empty.

Returns
boolean whether the move succeeded.

moveToLast

Added in API level 1
boolean moveToLast ()

Move the cursor to the last row.

This method will return false if the cursor is empty.

Returns
boolean whether the move succeeded.

moveToNext

Added in API level 1
boolean moveToNext ()

Move the cursor to the next row.

This method will return false if the cursor is already past the last entry in the result set.

Returns
boolean whether the move succeeded.

moveToPosition

Added in API level 1
boolean moveToPosition (int position)

Move the cursor to an absolute position. The valid range of values is -1 <= position <= count.

This method will return true if the request destination was reachable, otherwise, it returns false.

Parameters
position int: the zero-based position to move to.
Returns
boolean whether the requested move fully succeeded.

moveToPrevious

Added in API level 1
boolean moveToPrevious ()

Move the cursor to the previous row.

This method will return false if the cursor is already before the first entry in the result set.

Returns
boolean whether the move succeeded.

onMove

Added in API level 1
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 int: the position that we're moving from
newPosition int: the position that we're moving to
Returns
boolean true if the move is successful, false otherwise

registerContentObserver

Added in API level 1
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.

Parameters
observer ContentObserver: the object that gets notified when the content backing the cursor changes.

registerDataSetObserver

Added in API level 1
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().

Parameters
observer DataSetObserver: the object that gets notified when the cursors data set changes.

requery

Added in API level 1
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(). Since this method could execute a query on the database and potentially take a while, it could cause ANR if it is called on Main (UI) thread. A warning is printed if this method is being executed on Main thread.

Returns
boolean true if the requery succeeded, false if not, in which case the cursor becomes invalid.

respond

Added in API level 1
Bundle respond (Bundle extras)

This is an out-of-band way for the the user of a cursor to communicate with the cursor. The structure of each bundle is entirely defined by the cursor.

One use of this is to tell a cursor that it should retry its network request after it reported an error.

Parameters
extras Bundle: extra values, or Bundle.EMPTY. Never null.
Returns
Bundle extra values, or Bundle.EMPTY. Never null.

setExtras

Added in API level 23
void setExtras (Bundle extras)

Sets a Bundle that will be returned by getExtras().

Parameters
extras Bundle: Bundle to set, or null to set an empty bundle.

setNotificationUri

Added in API level 1
void setNotificationUri (ContentResolver cr, 
                Uri notifyUri)

Specifies a content URI to watch for changes.

Parameters
cr ContentResolver: The content resolver from the caller's context.
notifyUri Uri: The URI to watch for changes. This can be a specific row URI, or a base URI for a whole class of content.

unregisterContentObserver

Added in API level 1
void unregisterContentObserver (ContentObserver observer)

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

Parameters
observer ContentObserver: the object to unregister.

unregisterDataSetObserver

Added in API level 1
void unregisterDataSetObserver (DataSetObserver observer)

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

Parameters
observer DataSetObserver: the object to unregister.

Protected methods

checkPosition

Added in API level 1
void checkPosition ()

This function throws CursorIndexOutOfBoundsException if the cursor position is out of bounds. Subclass implementations of the get functions should call this before attempting to retrieve data.

Throws
CursorIndexOutOfBoundsException

finalize

Added in API level 1
void finalize ()

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. A subclass overrides the finalize method to dispose of system resources or to perform other cleanup.

The general contract of finalize is that it is invoked if and when the JavaTM virtual machine has determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, except as a result of an action taken by the finalization of some other object or class which is ready to be finalized. The finalize method may take any action, including making this object available again to other threads; the usual purpose of finalize, however, is to perform cleanup actions before the object is irrevocably discarded. For example, the finalize method for an object that represents an input/output connection might perform explicit I/O transactions to break the connection before the object is permanently discarded.

The finalize method of class Object performs no special action; it simply returns normally. Subclasses of Object may override this definition.

The Java programming language does not guarantee which thread will invoke the finalize method for any given object. It is guaranteed, however, that the thread that invokes finalize will not be holding any user-visible synchronization locks when finalize is invoked. If an uncaught exception is thrown by the finalize method, the exception is ignored and finalization of that object terminates.

After the finalize method has been invoked for an object, no further action is taken until the Java virtual machine has again determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, including possible actions by other objects or classes which are ready to be finalized, at which point the object may be discarded.

The finalize method is never invoked more than once by a Java virtual machine for any given object.

Any exception thrown by the finalize method causes the finalization of this object to be halted, but is otherwise ignored.

getUpdatedField

Added in API level 1
Object getUpdatedField (int columnIndex)

This method was deprecated in API level 11.
Always returns null since Cursors do not support updating rows

Parameters
columnIndex int
Returns
Object

isFieldUpdated

Added in API level 1
boolean isFieldUpdated (int columnIndex)

This method was deprecated in API level 11.
Always returns false since Cursors do not support updating rows

Parameters
columnIndex int
Returns
boolean

onChange

Added in API level 1
void onChange (boolean selfChange)

Subclasses must call this method when they finish committing updates to notify all observers.

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