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Cursor

public interface Cursor
implements Closeable

android.database.Cursor
Known Indirect Subclasses


This interface provides random read-write access to the result set returned by a database query.

Cursor implementations are not required to be synchronized so code using a Cursor from multiple threads should perform its own synchronization when using the Cursor.

Implementations should subclass AbstractCursor.

Summary

Constants

int FIELD_TYPE_BLOB

Value returned by getType(int) if the specified column type is blob

int FIELD_TYPE_FLOAT

Value returned by getType(int) if the specified column type is float

int FIELD_TYPE_INTEGER

Value returned by getType(int) if the specified column type is integer

int FIELD_TYPE_NULL

Value returned by getType(int) if the specified column is null

int FIELD_TYPE_STRING

Value returned by getType(int) if the specified column type is string

Public methods

abstract void close()

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

abstract void copyStringToBuffer(int columnIndex, CharArrayBuffer buffer)

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

abstract void deactivate()

This method was deprecated in API level 16. Since requery() is deprecated, so too is this.

abstract byte[] getBlob(int columnIndex)

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

abstract int getColumnCount()

Return total number of columns

abstract int getColumnIndex(String columnName)

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

abstract int getColumnIndexOrThrow(String columnName)

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

abstract 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 columnIndex)

Returns the value of the requested column as a double.

abstract Bundle getExtras()

Returns a bundle of extra values.

abstract float getFloat(int columnIndex)

Returns the value of the requested column as a float.

abstract int getInt(int columnIndex)

Returns the value of the requested column as an int.

abstract long getLong(int columnIndex)

Returns the value of the requested column as a long.

abstract 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).

abstract int getPosition()

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

abstract short getShort(int columnIndex)

Returns the value of the requested column as a short.

abstract String getString(int columnIndex)

Returns the value of the requested column as a String.

abstract int getType(int columnIndex)

Returns data type of the given column's value.

abstract boolean getWantsAllOnMoveCalls()

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

abstract boolean isAfterLast()

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

abstract boolean isBeforeFirst()

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

abstract boolean isClosed()

return true if the cursor is closed

abstract boolean isFirst()

Returns whether the cursor is pointing to the first row.

abstract boolean isLast()

Returns whether the cursor is pointing to the last row.

abstract boolean isNull(int columnIndex)

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

abstract boolean move(int offset)

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

abstract boolean moveToFirst()

Move the cursor to the first row.

abstract boolean moveToLast()

Move the cursor to the last row.

abstract boolean moveToNext()

Move the cursor to the next row.

abstract boolean moveToPosition(int position)

Move the cursor to an absolute position.

abstract boolean moveToPrevious()

Move the cursor to the previous row.

abstract void registerContentObserver(ContentObserver observer)

Register an observer that is called when changes happen to the content backing this cursor.

abstract 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().

abstract boolean requery()

This method was deprecated in API level 11. Don't use this. Just request a new cursor, so you can do this asynchronously and update your list view once the new cursor comes back.

abstract Bundle respond(Bundle extras)

This is an out-of-band way for the the user of a cursor to communicate with the cursor.

abstract void setExtras(Bundle extras)

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

abstract void setNotificationUri(ContentResolver cr, Uri uri)

Register to watch a content URI for changes.

abstract void unregisterContentObserver(ContentObserver observer)

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

abstract void unregisterDataSetObserver(DataSetObserver observer)

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

Inherited methods

From interface java.io.Closeable
From interface java.lang.AutoCloseable

Constants

FIELD_TYPE_BLOB

Added in API level 11
int FIELD_TYPE_BLOB

Value returned by getType(int) if the specified column type is blob

Constant Value: 4 (0x00000004)

FIELD_TYPE_FLOAT

Added in API level 11
int FIELD_TYPE_FLOAT

Value returned by getType(int) if the specified column type is float

Constant Value: 2 (0x00000002)

FIELD_TYPE_INTEGER

Added in API level 11
int FIELD_TYPE_INTEGER

Value returned by getType(int) if the specified column type is integer

Constant Value: 1 (0x00000001)

FIELD_TYPE_NULL

Added in API level 11
int FIELD_TYPE_NULL

Value returned by getType(int) if the specified column is null

Constant Value: 0 (0x00000000)

FIELD_TYPE_STRING

Added in API level 11
int FIELD_TYPE_STRING

Value returned by getType(int) if the specified column type is string

Constant Value: 3 (0x00000003)

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 ()

This method was deprecated in API level 16.
Since requery() is deprecated, so too is this.

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.

getBlob

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

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
columnIndex 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.

See also:

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
Throws
IllegalArgumentException if the column does not exist

See also:

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 columnIndex)

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
columnIndex 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 columnIndex)

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
columnIndex 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 columnIndex)

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
columnIndex 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 columnIndex)

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

getNotificationUri

Added in API level 19
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 columnIndex)

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
columnIndex 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 columnIndex)

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
columnIndex 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 columnIndex)

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
columnIndex 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().

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 columnIndex)

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

Parameters
columnIndex 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.

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.

See also:

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.

See also:

requery

Added in API level 1
boolean requery ()

This method was deprecated in API level 11.
Don't use this. Just request a new cursor, so you can do this asynchronously and update your list view once the new cursor comes back.

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 uri)

Register to watch a content URI for changes. This can be the URI of a specific data row (for example, "content://my_provider_type/23"), or a a generic URI for a content type.

Parameters
cr ContentResolver: The content resolver from the caller's context. The listener attached to this resolver will be notified.
uri Uri: The content URI to watch.

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.

See also:

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.

See also:

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