android.database
public
interface
android.database.Cursor
This interface provides random read-write access to the result set returned
by a database query.
Known Indirect Subclasses
Summary
Details
Public Methods
public
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.
public
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
| the zero-based index of the target column.
if the target column is null, return buffer |
buffer
| the buffer to copy the text into.
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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
byte[]
getBlob(int columnIndex)
Returns the value of the requested column as a byte array.
If the native content of that column is not blob exception may throw
Parameters
columnIndex
| the zero-based index of the target column. |
Returns
- the value of that column as a byte array.
public
int
getColumnCount()
Return total number of columns
public
int
getColumnIndex(String columnName)
This method is deprecated.
replaced by getColumnIndexOrThrow(String)
Returns the zero-based index for the given column name.
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.
public
int
getColumnIndexOrThrow(String columnName)
Returns the zero-based index for the given column name.
Parameters
columnName
| the name of the target column. |
Returns
- the zero-based column index for the given column name
public
String
getColumnName(int columnIndex)
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
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
- the names of the columns returned in this query.
public
int
getCount()
Returns the numbers of rows in the cursor.
Returns
- the number of rows in the cursor.
public
double
getDouble(int columnIndex)
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).
Parameters
columnIndex
| the zero-based index of the target column. |
Returns
- the value of that column as a double.
public
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
- cursor-defined values, or Bundle.EMTPY if there are no values. Never null.
public
float
getFloat(int columnIndex)
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).
Parameters
columnIndex
| the zero-based index of the target column. |
Returns
- the value of that column as a float.
public
int
getInt(int columnIndex)
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).
Parameters
columnIndex
| the zero-based index of the target column. |
Returns
- the value of that column as an int.
public
long
getLong(int columnIndex)
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).
Parameters
columnIndex
| the zero-based index of the target column. |
Returns
- the value of that column as a long.
public
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
- the current cursor position.
public
short
getShort(int columnIndex)
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).
Parameters
columnIndex
| the zero-based index of the target column. |
Returns
- the value of that column as a short.
public
String
getString(int columnIndex)
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).
Parameters
columnIndex
| the zero-based index of the target column. |
Returns
- the value of that column as a String.
public
boolean
getWantsAllOnMoveCalls()
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
boolean
isAfterLast()
Returns whether the cursor is pointing to the position after the last
row.
Returns
- whether the cursor is after the last result.
public
boolean
isBeforeFirst()
Returns whether the cursor is pointing to the position before the first
row.
Returns
- whether the cursor is before the first result.
public
boolean
isClosed()
return true if the cursor is closed
Returns
- true if the cursor is closed.
public
boolean
isFirst()
Returns whether the cursor is pointing to the first row.
Returns
- whether the cursor is pointing at the first entry.
public
boolean
isLast()
Returns whether the cursor is pointing to the last row.
Returns
- whether the cursor is pointing at the last entry.
public
boolean
isNull(int columnIndex)
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
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
| the offset to be applied from the current position. |
Returns
- whether the requested move fully succeeded.
public
boolean
moveToFirst()
Move the cursor to the first row.
This method will return false if the cursor is empty.
Returns
- whether the move succeeded.
public
boolean
moveToLast()
Move the cursor to the last row.
This method will return false if the cursor is empty.
Returns
- whether the move succeeded.
public
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
- whether the move succeeded.
public
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
| the zero-based position to move to. |
Returns
- whether the requested move fully succeeded.
public
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
- whether the move succeeded.
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.
Parameters
observer
| the object that gets notified when the content backing the cursor changes. |
public
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
| the object that gets notified when the cursors data set changes. |
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().
Returns
- true if the requery succeeded, false if not, in which case the
cursor becomes invalid.
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.EMTPY. Never null. |
Returns
- extra values, or Bundle.EMTPY. Never null.
public
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
| The content resolver from the caller's context. The listener attached to
this resolver will be notified. |
uri
| The content URI to watch.
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