public interface

Cursor

android.database.Cursor
Known Indirect Subclasses

Class Overview

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.

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

Constants

public static final int FIELD_TYPE_BLOB

Since: API Level 11

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

Constant Value: 4 (0x00000004)

public static final int FIELD_TYPE_FLOAT

Since: API Level 11

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

Constant Value: 2 (0x00000002)

public static final int FIELD_TYPE_INTEGER

Since: API Level 11

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

Constant Value: 1 (0x00000001)

public static final int FIELD_TYPE_NULL

Since: API Level 11

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

Constant Value: 0 (0x00000000)

public static final int FIELD_TYPE_STRING

Since: API Level 11

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

Constant Value: 3 (0x00000003)

Public Methods

public abstract void close ()

Since: API Level 1

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.

public abstract void copyStringToBuffer (int columnIndex, CharArrayBuffer buffer)

Since: API Level 1

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 the zero-based index of the target column. if the target column is null, return buffer
buffer the buffer to copy the text into.

public abstract void deactivate ()

Since: API Level 1

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 abstract byte[] getBlob (int columnIndex)

Since: API Level 1

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 the zero-based index of the target column.
Returns
  • the value of that column as a byte array.

public abstract int getColumnCount ()

Since: API Level 1

Return total number of columns

Returns
  • number of columns

public abstract int getColumnIndex (String columnName)

Since: API Level 1

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 the name of the target column.
Returns
  • the zero-based column index for the given column name, or -1 if the column name does not exist.
See Also

public abstract int getColumnIndexOrThrow (String columnName)

Since: API Level 1

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 the name of the target column.
Returns
  • the zero-based column index for the given column name
Throws
IllegalArgumentException if the column does not exist
See Also

public abstract String getColumnName (int columnIndex)

Since: API Level 1

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

Parameters
columnIndex the zero-based index of the target column.
Returns
  • the column name for the given column index.

public abstract String[] getColumnNames ()

Since: API Level 1

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
  • the names of the columns returned in this query.

public abstract int getCount ()

Since: API Level 1

Returns the numbers of rows in the cursor.

Returns
  • the number of rows in the cursor.

public abstract double getDouble (int columnIndex)

Since: API Level 1

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 the zero-based index of the target column.
Returns
  • the value of that column as a double.

public abstract Bundle getExtras ()

Since: API Level 1

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

public abstract float getFloat (int columnIndex)

Since: API Level 1

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 the zero-based index of the target column.
Returns
  • the value of that column as a float.

public abstract int getInt (int columnIndex)

Since: API Level 1

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

public abstract long getLong (int columnIndex)

Since: API Level 1

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 the zero-based index of the target column.
Returns
  • the value of that column as a long.

public abstract int getPosition ()

Since: API Level 1

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
  • the current cursor position.

public abstract short getShort (int columnIndex)

Since: API Level 1

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 the zero-based index of the target column.
Returns
  • the value of that column as a short.

public abstract String getString (int columnIndex)

Since: API Level 1

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 the zero-based index of the target column.
Returns
  • the value of that column as a String.

public abstract int getType (int columnIndex)

Since: API Level 11

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 the zero-based index of the target column.
Returns
  • column value type

public abstract boolean getWantsAllOnMoveCalls ()

Since: API Level 1

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

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

public abstract boolean isAfterLast ()

Since: API Level 1

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

Returns
  • whether the cursor is after the last result.

public abstract boolean isBeforeFirst ()

Since: API Level 1

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

Returns
  • whether the cursor is before the first result.

public abstract boolean isClosed ()

Since: API Level 1

return true if the cursor is closed

Returns
  • true if the cursor is closed.

public abstract boolean isFirst ()

Since: API Level 1

Returns whether the cursor is pointing to the first row.

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

public abstract boolean isLast ()

Since: API Level 1

Returns whether the cursor is pointing to the last row.

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

public abstract boolean isNull (int columnIndex)

Since: API Level 1

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

Parameters
columnIndex the zero-based index of the target column.
Returns
  • whether the column value is null.

public abstract boolean move (int offset)

Since: API Level 1

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 the offset to be applied from the current position.
Returns
  • whether the requested move fully succeeded.

public abstract boolean moveToFirst ()

Since: API Level 1

Move the cursor to the first row.

This method will return false if the cursor is empty.

Returns
  • whether the move succeeded.

public abstract boolean moveToLast ()

Since: API Level 1

Move the cursor to the last row.

This method will return false if the cursor is empty.

Returns
  • whether the move succeeded.

public abstract boolean moveToNext ()

Since: API Level 1

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
  • whether the move succeeded.

public abstract boolean moveToPosition (int position)

Since: API Level 1

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 the zero-based position to move to.
Returns
  • whether the requested move fully succeeded.

public abstract boolean moveToPrevious ()

Since: API Level 1

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
  • whether the move succeeded.

public abstract void registerContentObserver (ContentObserver observer)

Since: API Level 1

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 the object that gets notified when the content backing the cursor changes.
See Also

public abstract void registerDataSetObserver (DataSetObserver observer)

Since: API Level 1

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 the object that gets notified when the cursors data set changes.
See Also

public abstract boolean requery ()

Since: API Level 1

This method is deprecated.
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
  • true if the requery succeeded, false if not, in which case the cursor becomes invalid.

public abstract Bundle respond (Bundle extras)

Since: API Level 1

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 extra values, or Bundle.EMPTY. Never null.
Returns

public abstract void setNotificationUri (ContentResolver cr, Uri uri)

Since: API Level 1

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

public abstract void unregisterContentObserver (ContentObserver observer)

Since: API Level 1

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

Parameters
observer the object to unregister.
See Also

public abstract void unregisterDataSetObserver (DataSetObserver observer)

Since: API Level 1

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

Parameters
observer the object to unregister.
See Also