在片段中使用 Recyclerview

Question

我试图在片段中输出 Recycler 视图，但启动后出现空白屏幕。请告诉我如何修复它？我从 URL（XML 字符串）获取数据，然后解析它并将其写入 ArrayList。

BusinessFragment.java（在片段中，我使用第二个流获取 XML 字符串并进一步使用它（实际上有更多数据））：

'''

public class BusinessFragment extends Fragment {

    RecyclerView recyclerView;
    GetBusinessHelperAdapter getBusinessHelperAdapter;

    ArrayList<String> title = new ArrayList<>();

    class APITask extends AsyncTask<URL, Void,String> {
        @Override
        protected String doInBackground(URL... urls) {
            String response = null;
            try {
                response = getResponseFromUrl(urls[0]);

            } catch (IOException e) {
                e.printStackTrace();
            }
            return response;

        }
        protected void onPostExecute(String response) {

            try {
                boolean inEntry = false;
                String textValue = null;

                XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
                factory.setNamespaceAware(true);
                XmlPullParser xpp = factory.newPullParser();

                xpp.setInput(new StringReader(response));
                int eventType = xpp.getEventType();

                while (eventType != XmlPullParser.END_DOCUMENT) {

                    if (eventType == XmlPullParser.START_TAG) {
                        if (xpp.getName().equals("item")) {
                            inEntry = true;
                        }
                    } else if (eventType == XmlPullParser.TEXT) {
                        textValue = xpp.getText();
                    } else if (eventType == XmlPullParser.END_TAG) {
                        if (inEntry) {
                            if (xpp.getName().equals("item")) {
                                inEntry = false;
                            } else if (xpp.getName().equals("title")) {
                                title.add(textValue);
                            }
                        }
                    }
                    eventType = xpp.next();
                }

            } catch (XmlPullParserException | IOException e) {
                e.printStackTrace();
            }
        }

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_business, container, false);
        recyclerView = view.findViewById(R.id.recyclerView);
        getBusinessHelperAdapter = new GetBusinessHelperAdapter(title);
        recyclerView.setAdapter(getBusinessHelperAdapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
        return view;
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        URL generateURL = generateURL();
        new APITask().execute(generateURL);

    }
}

'''

GetBusinessHelperAdapter.java（Recyclerview 适配器）

'''

public class GetBusinessHelperAdapter extends
        RecyclerView.Adapter<GetBusinessHelperAdapter.MyViewClass> {
    ArrayList<String> title;

    public GetBusinessHelperAdapter(ArrayList<String> title){
        this.title=title;
    }

    public MyViewClass onCreateViewHolder(ViewGroup parent, int viewType){
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row,parent,false);
        MyViewClass myViewClass=new MyViewClass(view);
        return myViewClass;
    }

    public void onBindViewHolder(MyViewClass holder, @SuppressLint("RecyclerView") int position) {
        holder.title.setText(title.get(position));

        BusinessFragment businessFragment = new BusinessFragment();
        Bundle bundle = new Bundle();
        bundle.putString("title", title.get(position));
        businessFragment.setArguments(bundle);

    }
    public int getItemCount(){
        return title.size();
    }

    public class MyViewClass extends  RecyclerView.ViewHolder{
        TextView title;
        public MyViewClass(View itemView){
            super(itemView);
            title = itemView.findViewById(R.id.title);
        }
    }
}

'''

Answer 1

在BusinessFragment中file.java在while循环后添加了'get Business Helper Adapter.notifyDataSetChanged();'，一切都出来了

在片段中使用 Recyclerview

Using Recyclerview in a fragment

android

android-recyclerview

fragment