三个滑动标签中只有一个显示数据

Question

我有三个选项卡，每个选项卡都应显示从服务器获取的特定数据。我只创建了一个片段，根据打开的选项卡显示不同的信息，但是当应用程序启动时，只有一个选项卡显示数据，一段时间后，当我创建新的NamesAdapter时，它会在该行崩溃。

public class TabFragment extends Fragment {

    private static final String TAG = "TabFragment";
    int page;
    private ArrayList<Names> namesList;
    NamesAdapter adapter;
    ListView listView;


    public TabFragment() {
        // Required empty public constructor
    }

    public static TabFragment newInstance(int page) {
        TabFragment fragment = new TabFragment();

        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

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

        namesList = new ArrayList<>();
        listView = (ListView) getActivity().findViewById(R.id.listView);
        // Inflate the layout for this fragment
        new MyTask().execute();

        return inflater.inflate(R.layout.fragment_tab, container, false);


    }

    private class MyTask extends AsyncTask<String, String, Boolean> {


        @Override
        protected Boolean doInBackground(String... params) {

            String content = HttpManager.getData("http://union.ge/catalog/1455299520.json");

            Log.e("doInBackground", "was called");
            //return content;

            try {
                JSONArray json= new JSONArray(content);

                // get json objects one by one

                for (int i = 0; i < json.length(); i++){

                    Names names = new Names();
                    // this json object now has key-value pairs and
                    JSONObject jRealObject = json.getJSONObject(i).getJSONObject("name");
                    //Log.e("jrealobject", jRealObject.toString());

                    names.setEn(jRealObject.getString("en"));
                    names.setGe(jRealObject.getString("ge"));
                    names.setRu(jRealObject.getString("ru"));

                    //migebuli monacemebi shevinaxot chvens array-shi
                    namesList.add(names);

                }

                return true;

            } catch (JSONException e) {
                e.printStackTrace();
            }

            return false;

        }

// on postExecute method runs on the UI thread

            protected void onPostExecute(Boolean b) {
                super.onPostExecute(b);

                if(b){

                    adapter = new NamesAdapter(getContext(), R.layout.list_item, namesList, page);
                    Log.e(TAG, String.valueOf(page));

                    listView = (ListView) getActivity().findViewById(R.id.listView);
                    listView.setAdapter(adapter);

                } else {
                    Toast.makeText(getActivity(), "data was not parsed", Toast.LENGTH_SHORT).show();
                }
            }
    }


}

`

public class TabsAdapter extends FragmentPagerAdapter {


    final static int PAGE_COUNT = 3;
    private static final String TAG = "TabsAdapter";
    private String tabTitles[] = new String[] { "EN", "GE", "RU" };
    private Context context;


    public TabsAdapter(FragmentManager fm, Context context) {
        super(fm);
        this.context = context;
    }

    @Override
    public Fragment getItem(int position) {

        switch (position) {
            case 0:
                return TabFragment.newInstance(0);
            case 1:
                return TabFragment.newInstance(1);
            case 2:
                return TabFragment.newInstance(2);
            default:
                return null;
        }

    }

    @Override
    public int getCount() {
        return PAGE_COUNT;
    }

    public CharSequence getPageTitle(int position) {
        // Generate title based on item position
        return tabTitles[position];
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        super.destroyItem(container, position, object);
        FragmentManager manager = ((Fragment)object).getFragmentManager();
        android.support.v4.app.FragmentTransaction trans = manager.beginTransaction();
        trans.remove((Fragment)object);
        trans.commit();
    }



}

和Names类的适配器

public class NamesAdapter extends ArrayAdapter<Names> {

    private static final String TAG = "NamesAdapter";
    ArrayList<Names> items;
    Context context;
    int resource;
    int page;

    LayoutInflater vi;


    public NamesAdapter(Context context, int resource, ArrayList<Names> items, int pageNumber) {
        super(context, resource, items);

        this.context = context;
        this.resource = resource;
        this.items = items;
        this.page = pageNumber;


        vi = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    }

    public View getView(int position, View convertView, ViewGroup parent) {

        ViewHolder viewHolder;

        if (convertView == null){

           // convertView = vi.inflate(resource, null);
            convertView = LayoutInflater.from(context).inflate(R.layout.list_item, parent, false);
            viewHolder = new ViewHolder();

            viewHolder.textView = (TextView) convertView.findViewById(R.id.textView);

            convertView.setTag(viewHolder);

        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }


        switch (page) {
            case 0:
                viewHolder.textView.setText(items.get(position).getEn());
                break;
            case 1:
                viewHolder.textView.setText(items.get(position).getGe());
                break;
            case 2:
                viewHolder.textView.setText(items.get(position).getRu());
        }

        return convertView;
    }

    static class ViewHolder {
        public TextView textView;
    }

}

Answer 1

试试这个：

MyTask.class中的更改如下：

在doInBackground()中，替换

  

namesList.add（名称）;

与

  

publishProgress（名称）;

并覆盖此方法

@Override
protected void onProgressUpdate(String... values)
{
    super.onProgressUpdate(values);
    namesList.add(values[0])
}

创建适配器的方式不正确。见：

public class TabFragment extends Fragment {

    private static final String TAG = "TabFragment";
    private static final String PAGE_NO = "page_no";
    int page;
    private ArrayList<Names> namesList;
    NamesAdapter adapter;
    ListView listView;


    public TabFragment() {
        // Required empty public constructor
    }

    public static TabFragment newInstance(int page) {
        TabFragment fragment = new TabFragment();
        Bundle args = new Bundle();
        args.putInt(PAGE_NO, page);
        fragment .setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

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

        namesList = new ArrayList<>();
        listView = (ListView) getActivity().findViewById(R.id.listView);
        // Inflate the layout for this fragment

         page = getArguments().getInt(PAGE_NO);
         adapter = new NamesAdapter(getContext(), R.layout.list_item, namesList, page);
         Log.e(TAG, String.valueOf(page));

         listView = (ListView) getActivity().findViewById(R.id.listView);
         listView.setAdapter(adapter);

        return inflater.inflate(R.layout.fragment_tab, container, false);


    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState)
    {
        super.onViewCreated(view, savedInstanceState);

        // Start the task when view is created.
        new MyTask().execute();
    }


    private class MyTask extends AsyncTask<String, String, Boolean> {


        @Override
        protected Boolean doInBackground(String... params) {

            String content = HttpManager.getData("http://union.ge/catalog/1455299520.json");

            Log.e("doInBackground", "was called");
            //return content;

            try {
                JSONArray json= new JSONArray(content);

                // get json objects one by one

                for (int i = 0; i < json.length(); i++){

                    Names names = new Names();
                    // this json object now has key-value pairs and
                    JSONObject jRealObject = json.getJSONObject(i).getJSONObject("name");
                    //Log.e("jrealobject", jRealObject.toString());

                    names.setEn(jRealObject.getString("en"));
                    names.setGe(jRealObject.getString("ge"));
                    names.setRu(jRealObject.getString("ru"));

                    //migebuli monacemebi shevinaxot chvens array-shi
                    publishProgress(names);

                }

                return true;

            } catch (JSONException e) {
                e.printStackTrace();
            }

            return false;

        }

        @Override
        protected void onProgressUpdate(String... values)
        {
            super.onProgressUpdate(values);

            namesList.add(values[0]);
            adapter.notifyDataSetChanged();
        }


            // on postExecute method runs on the UI thread
            protected void onPostExecute(Boolean b) {
                super.onPostExecute(b);

                if(!b){
                   Toast.makeText(getActivity(), "data was not parsed", Toast.LENGTH_SHORT).show();
                } 
            }
    }


}