Question

我有一个AsyncTask，我使用doInBackground方法从端点通过HTTP获取大量数据。我正在尝试将该数据传递到一个CustomAdapter，它在onPostExecute（）方法中扩展BaseAdapter。但数据没有得到更新。知道我在这里做错了什么吗？

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


            View rootView = inflater.inflate(R.layout.fragment_main, container, false);

            ListView listView = (ListView) rootView.findViewById(R.id.listview_activity);

            EventsAdapter eventsAdapter = new EventsAdapter(getActivity(), objects);
            objects.add(new EventsObject("M2arius", "Shaorma2"));

            listView.setAdapter(eventsAdapter);

            return rootView;
        }

public class FetchEmailActivityTask extends AsyncTask<String, Void, String[]> {

    private final String LOG_TAG = FetchEmailActivityTask.class.getSimpleName();
    private final ProgressDialog dialog = new ProgressDialog(getActivity());

    @Override
    protected void onPreExecute() {
        dialog.setMessage("Please Wait.");
        dialog.setCancelable(true);
        dialog.show();
    }

    @Override
    protected String[] doInBackground(String... params) {

        ...
    try {
        return getActivityDataFromJson(activityJsonStr, limitParams);
    } catch (JSONException e){
        Log.e(LOG_TAG, e.getMessage(), e);
        e.printStackTrace();
    }
    // This will only happen if there was an error getting or parsing the activity.
    return null;
    }

    @Override
    protected void onPostExecute(String[] result){
       super.onPostExecute(result);
       ArrayList<EventsObject> eventsList = new ArrayList<EventsObject>();
        if (dialog.isShowing())
        {
            dialog.dismiss();
        }

        if (result != null){
            objects.add(new EventsObject("Marius", "Shaorma"));
            eventsAdapter = new EventsAdapter(getActivity(), objects);
            if (objects != null) {
                eventsAdapter.notifyDataSetChanged();
            } else {
                Log.v(LOG_TAG, "Objects: " + objects);
            }
        // New data is back from the server.  Hooray!
        }
   }
}

Answer 1

 eventsAdapter = new EventsAdapter(getActivity(), objects);

onPostExecute您正在创建适配器的新实例，但ListView包含旧实例。实例化后，再次调用setAdapter

if (getView() != null) {
    ListView listView = (ListView) getView().findViewById(R.id.listview_activity);
    if (listView != null) {
       listView.setAdapter(eventsAdapter);
    }
}

如何从onPostExecute（）中的doInBackground（）向BaseAdapter添加数据？

1 个答案: