Loading JSON content in fragment

Question

I'm very new to Android environment. I was wandering about retrieving JSON content from a web page, so I've found this tutorial to get JSON content from a url (Tutorial Link) and It works properly also with my data.

Now, what I wanted to do: a Tab application, with one of these tabs using that code to retrieve JSON data. I've used fragment and I tried to modify code in order to be compatible with fragments, anyway as I start the related tab, the application crashes.

As the previous tutorial works properly, I'm pretty sure the problem is on my newbie code.

FragmentTab1.Java

package com.alessandrobocci.fenice;
import java.util.ArrayList;
import java.util.HashMap;
import com.alessandrobocci.fenice.library.JSONParser;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Fragment;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;


public class FragmentTab1 extends Fragment {
    ListView list;
    TextView title;
    TextView name;
    TextView api;
    Button Btngetdata;
    ArrayList> oslist = new ArrayList>();

    //URL to get JSON Array
    private static String url = "http://10.0.2.2/test/read.php";

    //JSON Node Names 
    private static final String TAG_OS = "todo";
    private static final String TAG_VER = "title";

    JSONArray arr = null;
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        //Inflate the layout for this fragment
        //This layout contains your list view 
        View view = inflater.inflate(R.layout.fragmenttab1, container, false);
        title = (TextView)getView().findViewById(R.id.vers);
        //now you must initialize your list view
        list =(ListView)view.findViewById(R.id.listnews);
        new JSONParse().execute();

        return view;
    }
    private class JSONParse extends AsyncTask {
     private ProgressDialog pDialog;
    @Override
       protected void onPreExecute() {
           super.onPreExecute();
           pDialog = new ProgressDialog(getActivity());
           pDialog.setMessage("Getting Data ...");
           pDialog.setIndeterminate(false);
           pDialog.setCancelable(true);
           pDialog.show();            
    }

    @Override
       protected JSONObject doInBackground(String... args) {

        JSONParser jParser = new JSONParser();
        // Getting JSON from URL
        JSONObject json = jParser.getJSONFromUrl(url);
        return json;
    }
     @Override
    protected void onPostExecute(JSONObject json) {
         pDialog.dismiss();
         try {
            // Getting JSON Array from URL
            arr = json.getJSONArray(TAG_OS);
            for(int i = 0; i < arr.length(); i++){
            JSONObject c = arr.getJSONObject(i);
            // Storing  JSON item in a Variable
            String ver = c.getString(TAG_VER);
            // Adding value HashMap key => value
            HashMap map = new HashMap();
            map.put(TAG_VER, ver);
            oslist.add(map);
            //list=(ListView) getView().findViewById(R.id.list);
            ListAdapter adapter = new SimpleAdapter(getActivity(), oslist,
                R.layout.list_v,
                new String[] { TAG_VER }, new int[] {
                    R.id.vers});
            list.setAdapter(adapter);
            list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                    @Override
                    public void onItemClick(AdapterView parent, View view,
                                            int position, long id) {
                        Toast.makeText(getActivity(), "You Clicked at "+oslist.get(+position).get("title"), Toast.LENGTH_SHORT).show();
                    }
                });
            }
        } catch (JSONException e) {
          e.printStackTrace();
        }
       }
   }
}

logCat:

07-04 14:59:36.250: D/gralloc_goldfish(1081): Emulator without GPU emulation detected.
07-04 14:59:38.350: D/dalvikvm(1081): GC_CONCURRENT freed 154K, 10% free 6030K/6663K, paused 11ms+8ms
07-04 14:59:38.690: W/System.err(1081): org.apache.http.conn.HttpHostConnectException: Connection to http://10.0.2.2 refused
07-04 14:59:38.741: W/System.err(1081):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:183)
07-04 14:59:38.741: W/System.err(1081):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
07-04 14:59:38.881: W/System.err(1081):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
07-04 14:59:38.910: W/System.err(1081):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
07-04 14:59:38.910: W/System.err(1081):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
07-04 14:59:39.100: W/System.err(1081):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
07-04 14:59:39.150: W/System.err(1081):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
07-04 14:59:39.150: W/System.err(1081):     at com.alessandrobocci.fenice.library.JSONParser.getJSONFromUrl(JSONParser.java:38)
07-04 14:59:39.200: W/System.err(1081):     at com.alessandrobocci.fenice.FragmentTab1$JSONParse.doInBackground(FragmentTab1.java:72)
07-04 14:59:39.310: W/System.err(1081):     at com.alessandrobocci.fenice.FragmentTab1$JSONParse.doInBackground(FragmentTab1.java:1)
07-04 14:59:39.330: W/System.err(1081):     at android.os.AsyncTask$2.call(AsyncTask.java:264)
07-04 14:59:39.330: W/System.err(1081):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
07-04 14:59:39.390: W/System.err(1081):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
07-04 14:59:39.440: W/System.err(1081):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
07-04 14:59:39.440: W/System.err(1081):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
07-04 14:59:39.500: W/System.err(1081):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
07-04 14:59:39.510: W/System.err(1081):     at java.lang.Thread.run(Thread.java:856)
07-04 14:59:39.510: W/System.err(1081): Caused by: java.net.ConnectException: socket failed: EACCES (Permission denied)
07-04 14:59:39.611: W/System.err(1081):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:181)
07-04 14:59:39.710: W/System.err(1081):     ... 16 more
07-04 14:59:39.710: W/System.err(1081): Caused by: java.net.SocketException: socket failed: EACCES (Permission denied)
07-04 14:59:39.870: W/System.err(1081):     at libcore.io.IoBridge.socket(IoBridge.java:573)
07-04 14:59:39.870: W/System.err(1081):     at java.net.PlainSocketImpl.create(PlainSocketImpl.java:201)
07-04 14:59:39.870: W/System.err(1081):     at java.net.Socket.checkOpenAndCreate(Socket.java:663)
07-04 14:59:39.921: W/System.err(1081):     at java.net.Socket.connect(Socket.java:807)
07-04 14:59:39.979: W/System.err(1081):     at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119)
07-04 14:59:39.979: W/System.err(1081):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144)
07-04 14:59:40.051: W/System.err(1081):     ... 16 more
07-04 14:59:40.091: W/System.err(1081): Caused by: libcore.io.ErrnoException: socket failed: EACCES (Permission denied)
07-04 14:59:40.210: W/System.err(1081):     at libcore.io.Posix.socket(Native Method)
07-04 14:59:40.240: W/System.err(1081):     at libcore.io.BlockGuardOs.socket(BlockGuardOs.java:169)
07-04 14:59:40.260: W/System.err(1081):     at libcore.io.IoBridge.socket(IoBridge.java:558)
07-04 14:59:40.310: W/System.err(1081):     ... 21 more
07-04 14:59:40.370: E/Buffer Error(1081): Error converting result java.lang.NullPointerException
07-04 14:59:40.380: E/JSON Parser(1081): Error parsing data org.json.JSONException: End of input at character 0 of 
07-04 14:59:40.390: D/AndroidRuntime(1081): Shutting down VM
07-04 14:59:40.403: W/dalvikvm(1081): threadid=1: thread exiting with uncaught exception (group=0x409951f8)
07-04 14:59:40.452: E/AndroidRuntime(1081): FATAL EXCEPTION: main
07-04 14:59:40.452: E/AndroidRuntime(1081): java.lang.NullPointerException
07-04 14:59:40.452: E/AndroidRuntime(1081):     at com.alessandrobocci.fenice.FragmentTab1$JSONParse.onPostExecute(FragmentTab1.java:80)
07-04 14:59:40.452: E/AndroidRuntime(1081):     at com.alessandrobocci.fenice.FragmentTab1$JSONParse.onPostExecute(FragmentTab1.java:1)
07-04 14:59:40.452: E/AndroidRuntime(1081):     at android.os.AsyncTask.finish(AsyncTask.java:602)
07-04 14:59:40.452: E/AndroidRuntime(1081):     at android.os.AsyncTask.access$600(AsyncTask.java:156)
07-04 14:59:40.452: E/AndroidRuntime(1081):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:615)
07-04 14:59:40.452: E/AndroidRuntime(1081):     at android.os.Handler.dispatchMessage(Handler.java:99)
07-04 14:59:40.452: E/AndroidRuntime(1081):     at android.os.Looper.loop(Looper.java:137)
07-04 14:59:40.452: E/AndroidRuntime(1081):     at android.app.ActivityThread.main(ActivityThread.java:4340)
07-04 14:59:40.452: E/AndroidRuntime(1081):     at java.lang.reflect.Method.invokeNative(Native Method)
07-04 14:59:40.452: E/AndroidRuntime(1081):     at java.lang.reflect.Method.invoke(Method.java:511)
07-04 14:59:40.452: E/AndroidRuntime(1081):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
07-04 14:59:40.452: E/AndroidRuntime(1081):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
07-04 14:59:40.452: E/AndroidRuntime(1081):     at dalvik.system.NativeStart.main(Native Method)

If necessary, I'll post also the other code, I don't think anyway it's useful, as for example MainActivity.Java (who contains Tabs) works with simple FragmenTab code that retrieves some text. Hope I was clear, thanks.

Raghunandan · Accepted Answer

Change this

title = (TextView)getView().findViewById(R.id.vers);

to

title = (TextView)view.findViewById(R.id.vers);

title is probably null leading to NullPointerException which can be confirmed if you post the stacktrace.

One more tip you have the adapter set in the for loop. No need to do that. Add items to list and set adapter to listview once

Loading JSON content in fragment

Answers (1)

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