public class CursorLoader extends AsyncTaskLoader<Cursor>
ContentResolver and returns a Cursor.
This class implements the Loader protocol in a standard way for
querying cursors, building on AsyncTaskLoader to perform the cursor
query on a background thread so that it does not block the application's UI.
A CursorLoader must be built with the full information for the query to
perform, either through the
CursorLoader(Context, Uri, String[], String, String[], String) or
creating an empty instance with CursorLoader(Context) and filling
in the desired paramters with setUri(Uri), setSelection(String),
setSelectionArgs(String[]), setSortOrder(String),
and setProjection(String[]).
Loader.ForceLoadContentObserver, Loader.OnLoadCanceledListener<D>, Loader.OnLoadCompleteListener<D>| Constructor and Description |
|---|
CursorLoader(Context context)
Creates an empty unspecified CursorLoader.
|
CursorLoader(Context context,
Uri uri,
String[] projection,
String selection,
String[] selectionArgs,
String sortOrder)
Creates a fully-specified CursorLoader.
|
| Modifier and Type | Method and Description |
|---|---|
void |
cancelLoadInBackground()
Called on the main thread to abort a load in progress.
|
void |
deliverResult(Cursor cursor)
Sends the result of the load to the registered listener.
|
void |
dump(String prefix,
FileDescriptor fd,
PrintWriter writer,
String[] args)
Print the Loader's state into the given stream.
|
String[] |
getProjection() |
String |
getSelection() |
String[] |
getSelectionArgs() |
String |
getSortOrder() |
Uri |
getUri() |
Cursor |
loadInBackground()
Called on a worker thread to perform the actual load and to return
the result of the load operation.
|
void |
onCanceled(Cursor cursor)
Called if the task was canceled before it was completed.
|
protected void |
onReset()
Subclasses must implement this to take care of resetting their loader,
as per
Loader.reset(). |
protected void |
onStartLoading()
Starts an asynchronous load of the contacts list data.
|
protected void |
onStopLoading()
Must be called from the UI thread
|
void |
setProjection(String[] projection) |
void |
setSelection(String selection) |
void |
setSelectionArgs(String[] selectionArgs) |
void |
setSortOrder(String sortOrder) |
void |
setUri(Uri uri) |
isLoadInBackgroundCanceled, onCancelLoad, onForceLoad, onLoadInBackground, setUpdateThrottle, waitForLoaderabandon, cancelLoad, dataToString, deliverCancellation, forceLoad, getContext, getId, isAbandoned, isReset, isStarted, onAbandon, onContentChanged, registerListener, registerOnLoadCanceledListener, reset, startLoading, stopLoading, takeContentChanged, toString, unregisterListener, unregisterOnLoadCanceledListenerpublic CursorLoader(Context context)
setUri(Uri), setSelection(String), etc
to specify the query to perform.public CursorLoader(Context context, Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)
ContentResolver.query() for documentation on the meaning of the
parameters. These will be passed as-is to that call.public Cursor loadInBackground()
AsyncTaskLoaderLoader.deliverResult(D) on
the UI thread. If implementations need to process the results on the UI thread
they may override Loader.deliverResult(D) and do so there.
To support cancellation, this method should periodically check the value of
AsyncTaskLoader.isLoadInBackgroundCanceled() and terminate when it returns true.
Subclasses may also override AsyncTaskLoader.cancelLoadInBackground() to interrupt the load
directly instead of polling AsyncTaskLoader.isLoadInBackgroundCanceled().
When the load is canceled, this method may either return normally or throw
OperationCanceledException. In either case, the Loader will
call AsyncTaskLoader.onCanceled(D) to perform post-cancellation cleanup and to dispose of the
result object, if any.loadInBackground in class AsyncTaskLoader<Cursor>AsyncTaskLoader.isLoadInBackgroundCanceled(),
AsyncTaskLoader.cancelLoadInBackground(),
AsyncTaskLoader.onCanceled(D)public void cancelLoadInBackground()
AsyncTaskLoaderAsyncTaskLoader.loadInBackground()
that is running in the background on a worker thread.
This method should do nothing if AsyncTaskLoader.loadInBackground() has not started
running or if it has already finished.cancelLoadInBackground in class AsyncTaskLoader<Cursor>AsyncTaskLoader.loadInBackground()public void deliverResult(Cursor cursor)
LoaderdeliverResult in class Loader<Cursor>cursor - the result of the loadprotected void onStartLoading()
onStartLoading in class Loader<Cursor>protected void onStopLoading()
onStopLoading in class Loader<Cursor>public void onCanceled(Cursor cursor)
AsyncTaskLoaderonCanceled in class AsyncTaskLoader<Cursor>cursor - The value that was returned by AsyncTaskLoader.loadInBackground(), or null
if the task threw OperationCanceledException.protected void onReset()
LoaderLoader.reset(). This is not called by clients directly,
but as a result of a call to Loader.reset().
This will always be called from the process's main thread.public Uri getUri()
public void setUri(Uri uri)
public String[] getProjection()
public void setProjection(String[] projection)
public String getSelection()
public void setSelection(String selection)
public String[] getSelectionArgs()
public void setSelectionArgs(String[] selectionArgs)
public String getSortOrder()
public void setSortOrder(String sortOrder)
public void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args)
Loaderdump in class AsyncTaskLoader<Cursor>prefix - Text to print at the front of each line.fd - The raw file descriptor that the dump is being sent to.writer - A PrintWriter to which the dump is to be set.args - Additional arguments to the dump request.