public abstract class AbstractCursor extends Object implements CrossProcessCursor
| Modifier and Type | Field and Description |
|---|---|
protected boolean |
mClosed
Deprecated.
Use
isClosed() instead. |
protected Long |
mCurrentRowID |
protected int |
mPos
Deprecated.
Use
getPosition() instead. |
protected int |
mRowIdColumnIndex |
protected HashMap<Long,Map<String,Object>> |
mUpdatedRows |
FIELD_TYPE_BLOB, FIELD_TYPE_FLOAT, FIELD_TYPE_INTEGER, FIELD_TYPE_NULL, FIELD_TYPE_STRING| Constructor and Description |
|---|
AbstractCursor() |
| Modifier and Type | Method and Description |
|---|---|
protected void |
checkPosition()
This function throws CursorIndexOutOfBoundsException if
the cursor position is out of bounds.
|
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
Cursor.requery() is called. |
void |
fillWindow(int position,
CursorWindow window)
Copies cursor data into the window.
|
protected void |
finalize()
Invoked when the garbage collector has detected that this instance is no longer reachable.
|
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.
|
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.
|
protected Object |
getUpdatedField(int columnIndex)
Deprecated.
Always returns null since Cursors do not support updating rows
|
boolean |
getWantsAllOnMoveCalls()
Specifies a content URI to watch for changes.
|
CursorWindow |
getWindow()
If the cursor is backed by a
CursorWindow, returns a pre-filled
window with the contents of the cursor, otherwise null. |
boolean |
isAfterLast()
Returns whether the cursor is pointing to the position after the last
row.
|
boolean |
isBeforeFirst()
Returns whether the cursor is pointing to the position before the first
row.
|
boolean |
isClosed()
return true if the cursor is closed
|
protected boolean |
isFieldUpdated(int columnIndex)
Deprecated.
Always returns false since Cursors do not support updating rows
|
boolean |
isFirst()
Returns whether the cursor is pointing to the first row.
|
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. |
boolean |
move(int offset)
Move the cursor by a relative amount, forward or backward, from the
current position.
|
boolean |
moveToFirst()
Move the cursor to the first row.
|
boolean |
moveToLast()
Move the cursor to the last row.
|
boolean |
moveToNext()
Move the cursor to the next row.
|
boolean |
moveToPosition(int position)
Move the cursor to an absolute position.
|
boolean |
moveToPrevious()
Move the cursor to the previous row.
|
protected void |
onChange(boolean selfChange)
Subclasses must call this method when they finish committing updates to notify all
observers.
|
protected void |
onDeactivateOrClose() |
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 |
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
Cursor.requery(), Cursor.deactivate(), or Cursor.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 Cursor.getExtras(). |
void |
unregisterDataSetObserver(DataSetObserver observer)
Unregister an observer that has previously been registered with this
cursor via
#registerContentObserver. |
protected int mRowIdColumnIndex
protected Long mCurrentRowID
@Deprecated protected int mPos
getPosition() instead.@Deprecated protected boolean mClosed
isClosed() instead.public abstract int getCount()
Cursorpublic abstract String[] getColumnNames()
CursorgetColumnNames in interface Cursorpublic abstract String getString(int column)
CursorThe 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.
public abstract short getShort(int column)
CursorThe 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.
public abstract int getInt(int column)
CursorThe 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.
public abstract long getLong(int column)
CursorThe 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.
public abstract float getFloat(int column)
CursorThe 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.
public abstract double getDouble(int column)
CursorThe 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.
public abstract boolean isNull(int column)
Cursortrue if the value in the indicated column is null.public int getType(int column)
CursorCursor.getInt(int), Cursor.getFloat(int)
etc.
Returned column types are
public byte[] getBlob(int column)
CursorThe 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.
public CursorWindow getWindow()
CursorWindow, returns a pre-filled
window with the contents of the cursor, otherwise null.getWindow in interface CrossProcessCursorpublic int getColumnCount()
CursorgetColumnCount in interface Cursorpublic void deactivate()
CursorCursor.requery() is called.
Inactive Cursors use fewer resources than active Cursors.
Calling Cursor.requery() will make the cursor active again.deactivate in interface Cursorprotected void onDeactivateOrClose()
public boolean requery()
CursorCursor.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.public boolean isClosed()
Cursorpublic void close()
CursorCursor.deactivate() a call to Cursor.requery() will not make the Cursor valid
again.public boolean onMove(int oldPosition,
int newPosition)
onMove in interface CrossProcessCursoroldPosition - the position that we're moving fromnewPosition - the position that we're moving topublic void copyStringToBuffer(int columnIndex,
CharArrayBuffer buffer)
CursorcopyStringToBuffer in interface CursorcolumnIndex - the zero-based index of the target column.
if the target column is null, return bufferbuffer - the buffer to copy the text into.public final int getPosition()
CursorgetPosition in interface Cursorpublic final boolean moveToPosition(int position)
CursorThis method will return true if the request destination was reachable, otherwise, it returns false.
moveToPosition in interface Cursorposition - the zero-based position to move to.public void fillWindow(int position,
CursorWindow window)
CrossProcessCursorClears 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 Cursor.getPosition(),
is not changed by this method.
fillWindow in interface CrossProcessCursorposition - The zero-based index of the first row to copy into the window.window - The window to fill.public final boolean move(int offset)
CursorThis 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.
public final boolean moveToFirst()
CursorThis method will return false if the cursor is empty.
moveToFirst in interface Cursorpublic final boolean moveToLast()
CursorThis method will return false if the cursor is empty.
moveToLast in interface Cursorpublic final boolean moveToNext()
CursorThis method will return false if the cursor is already past the last entry in the result set.
moveToNext in interface Cursorpublic final boolean moveToPrevious()
CursorThis method will return false if the cursor is already before the first entry in the result set.
moveToPrevious in interface Cursorpublic final boolean isFirst()
Cursorpublic final boolean isLast()
Cursorpublic final boolean isBeforeFirst()
CursorisBeforeFirst in interface Cursorpublic final boolean isAfterLast()
CursorisAfterLast in interface Cursorpublic int getColumnIndex(String columnName)
CursorCursor.getColumnIndexOrThrow(String) instead, which
will make the error more clear.getColumnIndex in interface CursorcolumnName - the name of the target column.Cursor.getColumnIndexOrThrow(String)public int getColumnIndexOrThrow(String columnName)
CursorIllegalArgumentException if the column doesn't exist. If you're not sure if
a column will exist or not use Cursor.getColumnIndex(String) and check for -1, which
is more efficient than catching the exceptions.getColumnIndexOrThrow in interface CursorcolumnName - the name of the target column.Cursor.getColumnIndex(String)public String getColumnName(int columnIndex)
CursorgetColumnName in interface CursorcolumnIndex - the zero-based index of the target column.public void registerDataSetObserver(DataSetObserver observer)
CursorCursor.requery(), Cursor.deactivate(), or Cursor.close().registerDataSetObserver in interface Cursorobserver - the object that gets notified when the cursors data set changes.Cursor.unregisterDataSetObserver(DataSetObserver)public void unregisterDataSetObserver(DataSetObserver observer)
Cursor#registerContentObserver.unregisterDataSetObserver in interface Cursorobserver - the object to unregister.Cursor.registerDataSetObserver(DataSetObserver)protected void onChange(boolean selfChange)
selfChange - public boolean getWantsAllOnMoveCalls()
getWantsAllOnMoveCalls in interface Cursorcr - The content resolver from the caller's context.notifyUri - The URI to watch for changes. This can be a
specific row URI, or a base URI for a whole class of content.public void setExtras(Bundle extras)
CursorBundle that will be returned by Cursor.getExtras().public Bundle getExtras()
CursorThese values may only change when requery is called.
getExtras in interface CursorBundle.EMPTY if there
are no values. Never null.public Bundle respond(Bundle extras)
CursorOne use of this is to tell a cursor that it should retry its network request after it reported an error.
respond in interface Cursorextras - extra values, or Bundle.EMPTY.
Never null.Bundle.EMPTY.
Never null.@Deprecated protected boolean isFieldUpdated(int columnIndex)
@Deprecated protected Object getUpdatedField(int columnIndex)
protected void checkPosition()
CursorIndexOutOfBoundsExceptionprotected void finalize()
ObjectNote that objects that override finalize are significantly more expensive than
objects that don't. Finalizers may be run a long time after the object is no longer
reachable, depending on memory pressure, so it's a bad idea to rely on them for cleanup.
Note also that finalizers are run on a single VM-wide finalizer thread,
so doing blocking work in a finalizer is a bad idea. A finalizer is usually only necessary
for a class that has a native peer and needs to call a native method to destroy that peer.
Even then, it's better to provide an explicit close method (and implement
Closeable), and insist that callers manually dispose of instances. This
works well for something like files, but less well for something like a BigInteger
where typical calling code would have to deal with lots of temporaries. Unfortunately,
code that creates lots of temporaries is the worst kind of code from the point of view of
the single finalizer thread.
If you must use finalizers, consider at least providing your own
ReferenceQueue and having your own thread process that queue.
Unlike constructors, finalizers are not automatically chained. You are responsible for
calling super.finalize() yourself.
Uncaught exceptions thrown by finalizers are ignored and do not terminate the finalizer thread. See Effective Java Item 7, "Avoid finalizers" for more.