android notifydatasetchanged 刷新错误,在notifyDataSetChanged之后Android ListView没有刷新

我的ListFragment代码

public class ItemFragment extends ListFragment {

private DatabaseHandler dbHelper;

private static final String TITLE = "Items";

private static final String LOG_TAG = "debugger";

private ItemAdapter adapter;

private List items;

@Override

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

View view = inflater.inflate(R.layout.item_fragment_list, container, false);

return view;

}

@Override

public void onCreate(Bundle savedInstanceState) {

super.setHasOptionsMenu(true);

super.onCreate(savedInstanceState);

getActivity().setTitle(TITLE);

dbHelper = new DatabaseHandler(getActivity());

items = dbHelper.getItems();

adapter = new ItemAdapter(getActivity().getApplicationContext(), items);

this.setListAdapter(adapter);

}

@Override

public void onResume() {

super.onResume();

items.clear();

items = dbHelper.getItems(); //reload the items from database

adapter.notifyDataSetChanged();

}

@Override

public void onListItemClick(ListView l, View v, int position, long id) {

super.onListItemClick(l, v, position, id);

if(dbHelper != null) { //item is edited

Item item = (Item) this.getListAdapter().getItem(position);

Intent intent = new Intent(getActivity(), AddItemActivity.class);

intent.putExtra(IntentConstants.ITEM, item);

startActivity(intent);

}

}

}

有人可以帮忙吗？