new AsyncTask<Void, Void, Void>() {
        @Override
        protected Void doInBackground(Void... params) {

            listUsers.clear();
            databaseHelper = new DatabaseHelper(activity);
            listUsers.addAll(databaseHelper.getAllUser());
            return null;
        }
    }.execute();
}

servername = listUsers.get(0).getServer_Name();
    dbname = listUsers.get(0).getServer_db_name();
    dbuser = listUsers.get(0).getServer_db_user();
    dbpass = listUsers.get(0).getServer_db_pass();