Android - onLoadFinished not called

Question

I am facing an issue with Loader.

I have an Activity, which displays list of records retrieved from local DB. When the activity starts, records are automatically loaded

Answer 1

I have finally found the solution to this problem thanks to the discussion on

https://groups.google.com/forum/#!topic/android-developers/DbKL6PVyhLI

public static <T> void initLoader(final int loaderId, final Bundle args, final LoaderCallbacks<T> callbacks,
        final LoaderManager loaderManager) {
    final Loader<T> loader = loaderManager.getLoader(loaderId);
    if (loader != null && loader.isReset()) {
        loaderManager.restartLoader(loaderId, args, callbacks);
    } else {
        loaderManager.initLoader(loaderId, args, callbacks);
    }
}

In addition as of support library 28 make sure that you don't call initLoader from within Fragment.onCreate(). As the updated documentation states

You typically initialize a Loader within the activity's onCreate() method, or within the fragment's onActivityCreated() method.

see https://developer.android.com/guide/components/loaders

Answer 2

Check the support library.Use this import android.support.v4.app. Don't use android.app.loadermanager.

import android.support.v4.app.LoaderManager;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;

Initialize part

    LoaderManager mLoaderManager=getSupportLoaderManager(); 

      LoaderManager.LoaderCallbacks<Cursor> mCursorLoaderCallbacks=new LoaderManager.LoaderCallbacks<Cursor>() {
                @Override
                public Loader<Cursor> onCreateLoader(int id, Bundle cursor) {
                      return new CursorLoader(getActivity(), MediaStore.Video.Media.EXTERNAL_CONTENT_URI, COLUMNS_OF_INTEREST, null, null,
                            MediaStore.Video.Media.DATE_ADDED + " DESC");
                }
                @Override
                public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
                }


                @Override
                public void onLoaderReset(Loader<Cursor> loader) {              
               }
            };

  mLoaderManager.initLoader(URL_LOADER_EXTERNAL, null, mCursorLoaderCallbacks);

Answer 3

RaB solution dont work for me

My worked Solution, was always destroy Loader before restart

Loader<Cursor> loader = mLoaderManager.getLoader(mKeyLoader);
if (loader != null)
{
    mLoaderManager.destroyLoader(mKeyLoader);
}
mLoaderManager.restartLoader(mKeyLoader, args, this);

Answer 4

In addition to RaB's answer, if you are using a custom Loader, make sure that if you call super if you overwrite deliverResult():

@Override
public void deliverResult(D data) {
    super.deliverResult(data); // <--onLoadFinished() will not be called if you don't call this
    ...
}

Answer 5

fwiw, I had a similar problem from attempting to immediately restart the loader a second time, before the first onLoadFinished was called, resulting in neither being called.

this worked for me:

if( loader == null )
    loader = loaderMngr.initLoader(
        0, null, myLoaderCallbacks
        ); 
else if( loader.isAbandoned() )
    return;
else
    loaderMngr.restartLoader(
        0, null, myLoaderCallbacks
        );