Created
May 11, 2014 04:23
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A custom cursor loader to facilitate using a SQLite database with the Android LoaderManager framework, but without the need for a Content Provider.
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import android.content.Context; | |
import android.database.Cursor; | |
import android.support.v4.content.AsyncTaskLoader; | |
/** | |
* Used to write apps that run on platforms prior to Android 3.0. When running | |
* on Android 3.0 or above, this implementation is still used; it does not try | |
* to switch to the framework's implementation. See the framework SDK | |
* documentation for a class overview. | |
* | |
* This was based on the CursorLoader class | |
*/ | |
public abstract class SimpleCursorLoader extends AsyncTaskLoader<Cursor> { | |
private Cursor mCursor; | |
public SimpleCursorLoader(Context context) { | |
super(context); | |
} | |
/* Runs on a worker thread */ | |
@Override | |
public abstract Cursor loadInBackground(); | |
/* Runs on the UI thread */ | |
@Override | |
public void deliverResult(Cursor cursor) { | |
if (isReset()) { | |
// An async query came in while the loader is stopped | |
if (cursor != null) { | |
cursor.close(); | |
} | |
return; | |
} | |
Cursor oldCursor = mCursor; | |
mCursor = cursor; | |
if (isStarted()) { | |
super.deliverResult(cursor); | |
} | |
if (oldCursor != null && oldCursor != cursor && !oldCursor.isClosed()) { | |
oldCursor.close(); | |
} | |
} | |
/** | |
* Starts an asynchronous load of the contacts list data. When the result is ready the callbacks | |
* will be called on the UI thread. If a previous load has been completed and is still valid | |
* the result may be passed to the callbacks immediately. | |
* <p/> | |
* Must be called from the UI thread | |
*/ | |
@Override | |
protected void onStartLoading() { | |
if (mCursor != null) { | |
deliverResult(mCursor); | |
} | |
if (takeContentChanged() || mCursor == null) { | |
forceLoad(); | |
} | |
} | |
/** | |
* Must be called from the UI thread | |
*/ | |
@Override | |
protected void onStopLoading() { | |
// Attempt to cancel the current load task if possible. | |
cancelLoad(); | |
} | |
@Override | |
public void onCanceled(Cursor cursor) { | |
if (cursor != null && !cursor.isClosed()) { | |
cursor.close(); | |
} | |
} | |
@Override | |
protected void onReset() { | |
super.onReset(); | |
// Ensure the loader is stopped | |
onStopLoading(); | |
if (mCursor != null && !mCursor.isClosed()) { | |
mCursor.close(); | |
} | |
mCursor = null; | |
} | |
} |
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