Once you have a geodatabase file on the file system, you can add feature layers to the map from it...
Geodatabase geodatabase = new Geodatabase(path);
GeodatabaseFeatureTable featureTable = geodatabase.getGeodatabaseFeatureTableByLayerId(0);
// create a feature layer from the feature table
featureLayer = new FeatureLayer(featureTable);
map.getLayers().add(featureLayer);
Once the layer is in the Map, it behaves like any other full-fledged FeatureLayer.
Does this help?