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.
Nested Classes | |||||||||||
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AbstractCursor.SelfContentObserver | Cursors use this class to track changes others make to their URI. |
Fields | |||||||||||
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mClosed | |||||||||||
mContentResolver | |||||||||||
mCurrentRowID | |||||||||||
mPos | |||||||||||
mRowIdColumnIndex | This must be set to the index of the row ID column by any subclass that wishes to support updates. | ||||||||||
mUpdatedRows | This HashMap contains a mapping from Long rowIDs to another Map that maps from String column names to new values. |
Public Constructors | |||||||||||
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Public Methods | |||||||||||
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Closes the Cursor, releasing all of its resources and making it completely invalid.
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Retrieves the requested column text and stores it in the buffer provided.
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Deactivates the Cursor, making all calls on it fail until
requery() is called. | |||||||||||
Copy data from cursor to CursorWindow
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Returns the value of the requested column as a byte array.
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Return total number of columns
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Returns the zero-based index for the given column name, or -1 if the column doesn't exist.
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Returns the zero-based index for the given column name, or throws
IllegalArgumentException if the column doesn't exist. | |||||||||||
Returns the column name at the given zero-based column index.
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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.
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Returns the numbers of rows in the cursor.
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Returns the value of the requested column as a double.
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Returns a bundle of extra values.
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Returns the value of the requested column as a float.
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Returns the value of the requested column as an int.
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Returns the value of the requested column as a long.
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Returns the current position of the cursor in the row set.
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Returns the value of the requested column as a short.
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Returns the value of the requested column as a String.
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onMove() will only be called across processes if this method returns true.
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returns a pre-filled window, return NULL if no such window
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Returns whether the cursor is pointing to the position after the last
row.
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Returns whether the cursor is pointing to the position before the first
row.
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return true if the cursor is closed
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Returns whether the cursor is pointing to the first row.
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Returns whether the cursor is pointing to the last row.
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Returns
true if the value in the indicated column is null. | |||||||||||
Move the cursor by a relative amount, forward or backward, from the
current position.
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Move the cursor to the first row.
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Move the cursor to the last row.
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Move the cursor to the next row.
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Move the cursor to an absolute position.
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Move the cursor to the previous row.
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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.
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Register an observer that is called when changes happen to the content backing this cursor.
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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() . | |||||||||||
Performs the query that created the cursor again, refreshing its
contents.
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This is an out-of-band way for the the user of a cursor to communicate with the cursor.
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Specifies a content URI to watch for changes.
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Unregister an observer that has previously been registered with this
cursor via
registerContentObserver(ContentObserver) . | |||||||||||
Unregister an observer that has previously been registered with this
cursor via
registerContentObserver(ContentObserver) . |
Protected Methods | |||||||||||
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This function throws CursorIndexOutOfBoundsException if
the cursor position is out of bounds.
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Is called before the object's memory is being reclaimed by the VM.
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This function returns the uncommitted updated value for the field
at columnIndex.
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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. | |||||||||||
Subclasses must call this method when they finish committing updates to notify all
observers.
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[Expand]
Inherited Methods | |||||||||||
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From class java.lang.Object
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From interface android.database.CrossProcessCursor
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From interface android.database.Cursor
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This must be set to the index of the row ID column by any subclass that wishes to support updates.
This HashMap contains a mapping from Long rowIDs to another Map that maps from String column names to new values. A NULL value means to remove an existing value, and all numeric values are in their class forms, i.e. Integer, Long, Float, etc.
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.
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
columnIndex | the zero-based index of the target column. if the target column is null, return buffer |
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buffer | the buffer to copy the text into. |
Copy data from cursor to CursorWindow
position | start position of data |
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Returns the value of the requested column as a byte array.
If the native content of that column is not blob exception may throw
column | the zero-based index of the target column. |
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Return total number of columns
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.
columnName | the name of the target column. |
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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.
columnName | the name of the target column. |
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Returns the column name at the given zero-based column index.
columnIndex | the zero-based index of the target column. |
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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 numbers of rows in the cursor.
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).
column | the zero-based index of the target column. |
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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 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).
column | the zero-based index of the target column. |
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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).
column | the zero-based index of the target column. |
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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).
column | the zero-based index of the target column. |
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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 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).
column | the zero-based index of the target column. |
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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).
column | the zero-based index of the target column. |
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onMove() will only be called across processes if this method returns true.
returns a pre-filled window, return NULL if no such window
Returns whether the cursor is pointing to the position after the last row.
Returns whether the cursor is pointing to the position before the first row.
return true if the cursor is closed
Returns whether the cursor is pointing to the first row.
Returns whether the cursor is pointing to the last row.
Returns true
if the value in the indicated column is null.
column | the zero-based index of the target column. |
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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.
offset | the offset to be applied from the current position. |
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Move the cursor to the first row.
This method will return false if the cursor is empty.
Move the cursor to the last row.
This method will return false if the cursor is empty.
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.
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.
position | the zero-based position to move to. |
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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.
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.
oldPosition | the position that we're moving from |
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newPosition | the position that we're moving to |
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.
observer | the object that gets notified when the content backing the cursor changes. |
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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()
.
observer | the object that gets notified when the cursors data set changes. |
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Performs the query that created the cursor again, refreshing its
contents. This may be done at any time, including after a call to deactivate()
.
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.
extras | extra values, or Bundle.EMTPY. Never null. |
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Specifies a content URI to watch for changes.
cr | The content resolver from the caller's context. |
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notifyUri | The URI to watch for changes. This can be a specific row URI, or a base URI for a whole class of content. |
Unregister an observer that has previously been registered with this
cursor via registerContentObserver(ContentObserver)
.
observer | the object to unregister. |
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Unregister an observer that has previously been registered with this
cursor via registerContentObserver(ContentObserver)
.
observer | the object to unregister. |
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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.
Is called before the object's memory is being reclaimed by the VM. This can only happen once the VM has detected, during a run of the garbage collector, that the object is no longer reachable by any thread of the running application.
The method can be used to free system resources or perform other cleanup
before the object is garbage collected. The default implementation of the
method is empty, which is also expected by the VM, but subclasses can
override finalize()
as required. Uncaught exceptions which are
thrown during the execution of this method cause it to terminate
immediately but are otherwise ignored.
Note that the VM does guarantee that finalize()
is called at most
once for any object, but it doesn't guarantee when (if at all) finalize()
will be called. For example, object B's finalize()
can delay the execution of object A's finalize()
method and
therefore it can delay the reclamation of A's memory. To be safe, use a
ReferenceQueue
, because it provides more control
over the way the VM deals with references during garbage collection.
This function returns the uncommitted updated value for the field
at columnIndex. NOTE: This function and isFieldUpdated(int)
should
be called together inside of a block synchronized on mUpdatedRows.
columnIndex | the column index of the field to retrieve |
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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. NOTE: This function and
getUpdatedField(int)
should be called together inside of a
block synchronized on mUpdatedRows.
columnIndex | the column index of the field to check |
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Subclasses must call this method when they finish committing updates to notify all observers.