Json没有使用片段在所有选项卡中获取数据

Question

我在Android应用程序中使用列表视图有3个选项卡布局，我从json文件中获取数据。因此，当我运行应用程序数据时，第一个选项卡上，当我转到第二个数据时，数据不会出现相同的情况，第三个选项卡数据不会出现，但当我返回第二个选项卡时，数据将出现在2个选项卡上并且不在其他标签中。

这是我的片段类： -

package ww.ibc24.in;

import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import ww.ibc24.in.model.WorldsBillionaires;

public class BigNews extends Fragment {
    private static final String TAG = MainActivity.class.getSimpleName();
    //Billionaires json url
    private ProgressDialog pDialog;
    private List<WorldsBillionaires> worldsBillionairesList = new ArrayList<>();
    private ListView listView;
    JSONObject jsonobject;
    JSONArray jsonarray;
    ListView listview;
    ListViewAdapter adapter;
    ProgressDialog mProgressDialog;
    ArrayList<HashMap<String, String>> arraylist;
    static String RANK = "id";
    static String COUNTRY = "title";
    static String POPULATION = "category";
    static String FLAG = "image";
    static String DATE = "releaseYear";
    static String DESCRIPTION = "detail";
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.primary_layout, null);
        listView = (ListView) view.findViewById(R.id.list);
        // Showing progress dialog before making http request
        new DownloadJSON().execute();
        // Creating volley request obj
        return view;
    }
    // DownloadJSON AsyncTask
    private class DownloadJSON extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // Create a progressdialog
            mProgressDialog = new ProgressDialog(getActivity());
            // Set progressdialog title
            mProgressDialog.setTitle("Android JSON Parse Tutorial");
            // Set progressdialog message
            mProgressDialog.setMessage("Loading...");
            mProgressDialog.setIndeterminate(false);
            // Show progressdialog
            mProgressDialog.show();
        }

        @Override
        protected Void doInBackground(Void... params) {
            // Create an array
            arraylist = new ArrayList<HashMap<String, String>>();
            // Retrieve JSON Objects from the given URL address
            jsonobject = JSONfunctions
                    .getJSONfromURL("http://192.168.25.18:8080/bignews.json");

            try {
                // Locate the array name in JSON
                jsonarray = jsonobject.getJSONArray("worldpopulation");

                for (int i = 0; i < jsonarray.length(); i++) {
                    HashMap<String, String> map = new HashMap<String, String>();
                    jsonobject = jsonarray.getJSONObject(i);
                    // Retrive JSON Objects
                    //map.put("id", jsonobject.getString("id"));
                    map.put("title", jsonobject.getString("title"));
                    map.put("category", jsonobject.getString("category"));
                    map.put("image", jsonobject.getString("image"));
                    map.put("releaseYear", jsonobject.getString("releaseYear"));
                    map.put("detail", jsonobject.getString("detail"));
                    // Set the JSON Objects into the array
                    arraylist.add(map);
                }
            } catch (JSONException e) {
                Log.e("Error", e.getMessage());
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(Void args) {
            // Locate the listview in listview_main.xml
            listview = (ListView) getActivity().findViewById(R.id.list);
            arraylist.clear();
            // Pass the results into ListViewAdapter.java
            adapter = new ListViewAdapter(getActivity(), arraylist);
            // Set the adapter to the ListView
            listview.setAdapter(adapter);
            // Close the progressdialog
            mProgressDialog.dismiss();
        }
    }
}





and this is my adapter class:-




package ww.ibc24.in;

import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.HashMap;

public class ListViewAdapter extends BaseAdapter {

    // Declare Variables
    Context context;
    LayoutInflater inflater;
    ArrayList<HashMap<String, String>> data;
    ImageLoader imageLoader;
    HashMap<String, String> resultp = new HashMap<String, String>();

    public ListViewAdapter(Context context,
            ArrayList<HashMap<String, String>> arraylist) {
        this.context = context;
        data = arraylist;
        imageLoader = new ImageLoader(context);
    }

    @Override
    public int getCount() {
        return data.size();
    }

    @Override
    public Object getItem(int position) {
        return null;
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    public View getView(final int position, View convertView, ViewGroup parent) {
        // Declare Variables
        TextView rank;
        TextView country;
        TextView population;
        ImageView flag;
        TextView date;
        TextView desc;

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

        View itemView = inflater.inflate(R.layout.listview_item, parent, false);
        // Get the position
        resultp = data.get(position);

        // Locate the TextViews in listview_item.xml
        rank = (TextView) itemView.findViewById(R.id.rank);
        country = (TextView) itemView.findViewById(R.id.country);
        date = (TextView) itemView.findViewById(R.id.date);
        population = (TextView) itemView.findViewById(R.id.population);
        desc = (TextView) itemView.findViewById(R.id.desc);

        // Locate the ImageView in listview_item.xml
        flag = (ImageView) itemView.findViewById(R.id.thumbnail);

        // Capture position and set results to the TextViews
        rank.setText(resultp.get(BigNews.RANK));
        country.setText(resultp.get(BigNews.COUNTRY));
        population.setText(resultp.get(BigNews.POPULATION));
        date.setText(resultp.get(BigNews.DATE));
        desc.setText(resultp.get(BigNews.DESCRIPTION));
        // Capture position and set results to the ImageView
        // Passes flag images URL into ImageLoader.class
        imageLoader.DisplayImage(resultp.get(BigNews.FLAG), flag);
        // Capture ListView item click
        itemView.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // Get the position
                resultp = data.get(position);
                Intent intent = new Intent(context, SingleItemView.class);
                // Pass all data rank
                intent.putExtra("id", resultp.get(BigNews.RANK));
                // Pass all data country
                intent.putExtra("title", resultp.get(BigNews.COUNTRY));
                // Pass all data population
                intent.putExtra("category",resultp.get(BigNews.POPULATION));
                // Pass all data flag
                intent.putExtra("image", resultp.get(BigNews.FLAG));
                intent.putExtra("releaseYear", resultp.get(BigNews.DATE));
                intent.putExtra("detail", resultp.get(BigNews.DESCRIPTION));
                // Start SingleItemView Class
                context.startActivity(intent);

            }
        });
        return itemView;
    }
}