some thing wrong in json parsing in android

Question

I am android beginner and trying to fetch pnr status using json here is my code which is not working please help me . There is some null exception when checking the console it said there is some problem in doinbackground method do not understand what it said...

public class Riki extends Activity {
    TextView httpStuff;
    HttpClient client;
    JSONObject json;    
    final static String URL = "http://www.railpnrapi.com/";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.httpexample);
        httpStuff = (TextView) findViewById(R.id.tvHttp);
        client = new DefaultHttpClient();       
        new Read().execute("tnum");
    }

    public JSONObject PNR(String username)
            throws ClientProtocolException, IOException, JSONException {
        StringBuilder url = new StringBuilder(URL);
        url.append(username);

        HttpGet get = new HttpGet(url.toString());
        HttpResponse r = client.execute(get);
        int status = r.getStatusLine().getStatusCode();
        httpStuff.setText(url);
        httpStuff.setText(status);
        if (status == 200) {
            HttpEntity e = r.getEntity();
            String data = EntityUtils.toString(e);
            JSONArray timeline = new JSONArray(data);
            JSONObject last = timeline.getJSONObject(0);
            return last;
        } else {
            Toast.makeText(Riki.this, "error", Toast.LENGTH_SHORT);
            return null;
        }
    }

    public class Read extends AsyncTask<String, Integer, String>{

        @Override
        protected String doInBackground(String... params) {
            // TODO Auto-generated method stub
            try {
                json = PNR("8506503026");
                return json.getString(params[0]);
            } catch (ClientProtocolException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

            return null;
        }

        @Override
        protected void onPostExecute(String result) {
            // TODO Auto-generated method stub
            httpStuff.setText(result);
        }

    }
}

12-06 16:28:48.180: E/AndroidRuntime(2871): FATAL EXCEPTION: AsyncTask #2
12-06 16:28:48.180: E/AndroidRuntime(2871): java.lang.RuntimeException: An error occured while executing doInBackground()
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.os.AsyncTask$3.done(AsyncTask.java:200)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at java.util.concurrent.FutureTask.setException(FutureTask.java:125)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at java.util.concurrent.FutureTask.run(FutureTask.java:138)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at java.lang.Thread.run(Thread.java:1019)
12-06 16:28:48.180: E/AndroidRuntime(2871): Caused by: android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.view.ViewRoot.checkThread(ViewRoot.java:3011)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.view.ViewRoot.requestLayout(ViewRoot.java:630)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.view.View.requestLayout(View.java:8268)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.view.View.requestLayout(View.java:8268)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.view.View.requestLayout(View.java:8268)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.view.View.requestLayout(View.java:8268)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.view.View.requestLayout(View.java:8268)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.widget.ScrollView.requestLayout(ScrollView.java:1289)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.view.View.requestLayout(View.java:8268)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.widget.TextView.checkForRelayout(TextView.java:5547)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.widget.TextView.setText(TextView.java:2730)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.widget.TextView.setText(TextView.java:2598)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.widget.TextView.setText(TextView.java:2573)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at com.example.coder.Riki.PNR(Riki.java:49)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at com.example.coder.Riki$Read.doInBackground(Riki.java:69)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at com.example.coder.Riki$Read.doInBackground(Riki.java:1)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at android.os.AsyncTask$2.call(AsyncTask.java:185)
12-06 16:28:48.180: E/AndroidRuntime(2871):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)

Answer 1

You're calling .setText() on some TextViews in PNR(), which you're then calling from doInBackground(). setText() is a UI operation and doInBackground() is not allowed to touch the UI thread.

If you want to do some UI manipulation from within an AsyncTask, you should be doing it in onPreExecute() or onPostExecute().