@Override
 protected void registerViews() {
   refreshScrollView.setMode(PullToRefreshBase.Mode.PULL_FROM_START);
   refreshScrollView.setOnRefreshListener(
       new PullToRefreshBase.OnRefreshListener<ScrollView>() {
         @Override
         public void onRefresh(PullToRefreshBase<ScrollView> refreshView) {
           getProductClass();
         }
       });
   listView.setOnItemClickListener(
       new AdapterView.OnItemClickListener() {
         @Override
         public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
           select(productClasses.get(i));
         }
       });
 }
 @Override
 protected void initViews() {
   listView.setAdapter(productClassAdapter);
 }