private static final String TAG = MainActivity.class.getSimpleName();

// permission to read external storage
private final String[] reqPermission = new String[] { Manifest.permission.READ_EXTERNAL_STORAGE };

private MapView mMapView;



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // create map and add to map view
    //ArcGISMap map = new ArcGISMap(Basemap.createStreets());
    //mMapView = findViewById(R.id.mapView);
   // mMapView.setMap(map);

    // For API level 23+ request permission at runtime
    if (ContextCompat.checkSelfPermission(MainActivity.this, reqPermission[0]) == PackageManager.PERMISSION_GRANTED) {
        LoadGeodatabase loadGeodatabase = new LoadGeodatabase();
        loadGeodatabase.execute();
    } else {
        // request permission
        int requestCode = 2;
        ActivityCompat.requestPermissions(MainActivity.this, reqPermission, requestCode);
    }
}

@Override
    protected Void doInBackground(Void... params){

    // create path to local geodatabase
    String path = Environment.getExternalStorageDirectory() + getString(R.string.config_data_sdcard_offline_dir)
            + getString(R.string.config_geodb_name);


        // create a new geodatabase from local path
        final Geodatabase geodatabase = new Geodatabase(path);
        geodatabase.loadAsync();
        //Takes each layer one by one from the Geodatabase and adds it to the MapView

        geodatabase.addDoneLoadingListener(() -> {
            if  (geodatabase.getLoadStatus() == LoadStatus.LOADED) {

                for (int i = (geodatabase.getGeodatabaseFeatureTables().size()) - 1; i >= 0; i--) {
                    GeodatabaseFeatureTable geodatabaseFeatureTable = geodatabase.getGeodatabaseFeatureTableByServiceLayerId(i);

                    final FeatureLayer featureLayer = new FeatureLayer(geodatabaseFeatureTable);

                    featureLayer.addDoneLoadingListener(() -> {
                        if (featureLayer.getLoadStatus() == LoadStatus.LOADED) {
                            // set viewpoint to the feature layer's extent
                            mMapView.setViewpointAsync(new Viewpoint(featureLayer.getFullExtent()));
                        } else {
                            Toast.makeText(MainActivity.this, "Feature Layer failed to load!", Toast.LENGTH_LONG).show();
                            Log.e(TAG, "Feature Layer failed to load!");
                        }
                    });
                    // add feature layer to the map
                    mMapView.getMap().getOperationalLayers().add(featureLayer);
                }


            } else {
                Toast.makeText(MainActivity.this, "Geodatabase failed to load!", Toast.LENGTH_LONG).show();
                Log.e(TAG, "Geodatabase failed to load!");
            }
        });


    return null;
}

/**
 * Handle the permissions request response
 */
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
        LoadGeodatabase loadGeodatabase = new LoadGeodatabase();
        loadGeodatabase.execute();
    } else {
        // report to user that permission was denied
        Toast.makeText(MainActivity.this, getResources().getString(R.string.location_permission_denied),
                Toast.LENGTH_SHORT).show();
    }
}

@Override
protected void onPause() {
    super.onPause();
    mMapView.pause();
}

@Override
protected void onResume() {
    super.onResume();
    mMapView.resume();
}