Question

我是Android开发的新手，我现在卡住了，因为我的自定义适配器中的getView方法没有被调用。我试图显示我从API收集的数据，解析它，并将其渲染到android studio的屏幕上。请帮忙！

这是我的遗产：

public class eventsFragment extends Fragment {
View myView;
View rootView;
ArrayList<events> eventList;
private ListView LV;
private ProgressDialog pDialog;
private static String url = "https://kambuku.com/app/tickets";


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    rootView = inflater.inflate(R.layout.events_layout, container, false);
    eventList = new ArrayList<>();
    LV = (ListView) rootView.findViewById(R.id.List);

    //GET CONNECTION INFO
    myView = inflater.inflate(R.layout.events_layout, container, false);
    ConnectivityManager connectivityManager = (ConnectivityManager)
            getActivity().getSystemService(Context.CONNECTIVITY_SERVICE);

    NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
    if (networkInfo != null && networkInfo.isConnected()) {
        new getAllEvents().execute();
    } else {
        Toast.makeText(getActivity().getApplicationContext(),
                "No Active Connection!",
                Toast.LENGTH_LONG)
                .show();
    }

    return myView;

}


private class getAllEvents extends AsyncTask<Void, Void, Void> {

    String feed = "";

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        //Show Progress Dialog
        pDialog = new ProgressDialog(getActivity());
        pDialog.setMessage("Please wait... Fetching your Events");
        pDialog.setCancelable(true);
        pDialog.show();
    }


    @Override
    protected Void doInBackground(Void... arg0) {
        String Result;
        String DEBUG_TAG = "EVENTS";

        HttpHandler handle = new HttpHandler();
        String jsonStr = null;
        try {
            jsonStr = handle.EventsConnection(url, DEBUG_TAG);
        } catch (IOException e) {
            e.printStackTrace();
        }

        Result = jsonStr;

        Log.e(DEBUG_TAG, "JSON RESPONSE IS" + Result);
        if (Result != null) {
            try {
                JSONObject jsonObject = new JSONObject(Result);
                Log.e(DEBUG_TAG, "JSON OBJECT IS" + jsonObject);

                //GET JSON ARRAY NODE
                JSONArray tickets = jsonObject.getJSONArray("tickets");
                Log.e(DEBUG_TAG, "JSON TICKET ARRAY LENGTH IS" + tickets.length());

                for (int i = 0; i < tickets.length(); i++) {
                    JSONObject t = tickets.getJSONObject(i);

                    Log.e(DEBUG_TAG, "JSON OBJECT " + i + " is " + t);


                    events event = new events();

                    event.setEventName(t.getString("eventName"));
                    event.setId(t.getString("id"));
                    event.setVenue(t.getString("venue"));
                    event.setCity(t.getString("city"));
                    event.setArtwork("https://kambuku.com/"+t.getString("artwork"));
                    event.setHost(t.getString("host"));
                    event.setNotes(t.getString("notes"));
                    event.setPrice(t.getString("price"));
                    event.setEventDate(t.getString("eventDate"));


                    eventList.add(event);
                }

            } catch (final JSONException e) {
                Log.e(DEBUG_TAG, "Json parsing error: " + e.getMessage());
                getActivity().runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(getActivity().getApplicationContext(),
                                "Json parsing error: " + e.getMessage(),
                                Toast.LENGTH_LONG)
                                .show();
                    }
                });
            }
        } else {
            Log.e(DEBUG_TAG, "Couldn't get json from server.");
            getActivity().runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(getActivity().getApplicationContext(),
                            "Couldn't get json from server. Check LogCat for possible errors!",
                            Toast.LENGTH_LONG)
                            .show();
                }
            });
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        Log.e("PostExecute", "YOUR LIST ARE "+eventList);
        eventsAdapter eventAdapter = new eventsAdapter(getActivity().getApplicationContext(), R.layout.event_item, eventList);
        LV.setAdapter(eventAdapter);
        if (pDialog.isShowing())
            pDialog.dismiss();

    }

}

}

这是我的适配器：

public class eventsAdapter extends ArrayAdapter {
private ArrayList<events> ArrayListEvents;
private int Resource;
private Context context;
private LayoutInflater inflater;

public eventsAdapter(Context context, int resource, ArrayList<events> objects) {
    super(context, resource, objects);

    Log.e("ADAPTER", "OBJECTS ARE "+objects);
    Log.e("ADAPTER", "RESOURCES ARE "+resource);

    ArrayListEvents = objects;
    Resource = resource;
    this.context = context;
    inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}


@Override
public View getView(int position, View convertView, ViewGroup parent) {
    Log.e("ADAPTER", "WE ARE HERE");
    ViewHolder holder;
    if (convertView == null) {
        convertView = inflater.inflate(Resource, null);
        holder = new ViewHolder();

        holder.artwork = (ImageView) convertView.findViewById(R.id.Artwork);
        holder.eventName = (TextView) convertView.findViewById(R.id.eventName);
        holder.eventNotes = (TextView) convertView.findViewById(R.id.eventNotes);

        convertView.setTag(holder);
    } else {
        holder = (eventsAdapter.ViewHolder)convertView.getTag();
    }

    new DownloadImageResource(holder.artwork).execute(ArrayListEvents.get(position).getArtwork());
    holder.eventName.setText(ArrayListEvents.get(position).getEventName());
    holder.eventNotes.setText(ArrayListEvents.get(position).getNotes());
    Log.e("Holder", "Holder"+holder.eventName.getText());
    return convertView;
}

private static class ViewHolder {
    ImageView artwork;
    TextView eventName;
    TextView eventNotes;
}


private class DownloadImageResource extends AsyncTask<String, Void, Bitmap>
{
    ImageView Artwork;

    DownloadImageResource(ImageView Artwork)
    {
        this.Artwork = Artwork;
    }

    protected Bitmap doInBackground(String... urls)
    {
        String urlDisplay = urls[0];
        Bitmap conn = null;
        try
        {
            InputStream inputStream = new java.net.URL(urlDisplay).openStream();
            conn = BitmapFactory.decodeStream(inputStream);

        }catch (Exception e){
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }
        return conn;
    }

    protected void onPostExecute(Bitmap result)
    {
        Log.e("Image", "Image Download"+result);
        Artwork.setImageBitmap(result);
    }
}

}

Answer 1

Override getItemCount method in your adapter.

@Override public int getItemCount() { return ArrayListEvents .size(); }

Answer 2

Your problem is you are executing nested AsyncTask. I.e. you are running another task for each row in the listview, which is already running a task. This is not good in Android. See this question for more details.

我的数组适配器中没有调用我的getView方法

2 个答案: