how to use Json parser android?

Question 1

you are doing network work in main thread that why this error accours. for developing process you use this but not to live apps.

put this code in your Activity in oncreate method after setcontentView(layout)

if (android.os.Build.VERSION.SDK_INT > 9) {
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
                .permitAll().build();
        StrictMode.setThreadPolicy(policy);
    }

Question 2

don't use network activities in main thread.This exception only thrown for applications targeting the Honeycomb SDK or higher. perform all the network related task in separate thread . your problem will get solved.

Question 3

Caused by: android.os.NetworkOnMainThreadException

You are running network realted operation on the ui thread.

HttpResponse httpResponse = httpClient.execute(httpPost);

The above statement must be in a thread or asynctask doInbackground.

http://developer.android.com/reference/android/os/AsyncTask.html

Invoke asynctask on the ui thread new TheTask().execute()

class TheTask extends AsyncTask<Void ,Void, Void>{

        @Override
        protected Void doInBackground(Void... params) {
                   JSONObject jobject =getJSONFromUrl(String url);
            return null;

        }
    }

Question 4

Caused by: android.os.NetworkOnMainThreadException

You cannot use HttpResponse on main thread. You must use an AsyncTask get Json from Web.

Read this;

http://developer.android.com/reference/android/os/AsyncTask.html

Question 5

public static JSONObject responseForSignin(final String uname,final String pwd) {

         JSONObject jsonResponse = null;
        HttpParams httpParameters = new BasicHttpParams();
        int connectionTimeout = 1000*12;
        int socketTimeout = 1000*13;
        HttpConnectionParams.setConnectionTimeout(httpParameters, connectionTimeout);
        HttpConnectionParams.setSoTimeout(httpParameters, socketTimeout);
        // Create a new HttpClient and Post Header
        HttpClient httpClient = new DefaultHttpClient(httpParameters);
        HttpPost httpPost = new HttpPost("URL");
        httpPost.setHeader("Content-Type", "application/x-www-form-urlencoded");

        try {
            // Add your data

            List<NameValuePair> signinDetails = new ArrayList<NameValuePair>();
            signinDetails.add(new BasicNameValuePair("name", uname));
                         signinDetails.add(new BasicNameValuePair("pwd", pwd));
            httpPost.setEntity(new UrlEncodedFormEntity(signinDetails));
            // Execute HTTP Post Request
            HttpResponse httpResponse = httpClient.execute(httpPost);
            Log.v("Post Status", "Code: "+ httpResponse.getStatusLine().getStatusCode());
            responseCode = httpResponse.getStatusLine().getStatusCode();
                Log.e("responseCode", String.valueOf("response code"+responseCode));
                HttpEntity entity = httpResponse.getEntity();
                Log.e("entity", String.valueOf(entity));
                if (entity != null) {

                    if (entity != null) {

                        String responseBody = EntityUtils.toString(entity);
                        JSONTokener jsonTokener = new JSONTokener(responseBody);
                        jsonResponse = new JSONObject(jsonTokener);
                        JSONObject response = jsonResponse.getJSONObject("response");
                        // Getting String inside response object
                        String status = response.getString("status");
                        String message = response.getString("message");

                    }
                } // if (entity != null) end
        } 

        catch (SocketException seExp) 
        {

        }
        catch (ConnectTimeoutException cteExp) 
        {
        // TODO Auto-generated catch block

        }
        catch (ClientProtocolException cpeExp) {
            // TODO Auto-generated catch block
        } 

          catch (UnknownHostException e) {
                // TODO Auto-generated catch block

                e.printStackTrace();
            }
        catch (Exception allExp) {
            // TODO Auto-generated catch block
        }       
        return jsonResponse;
    }

try this

public class RequestLogInFromServer extends AsyncTask<Object, Object, Object>
    {

        private ProgressDialog progressDialog;


        @Override
        protected Object doInBackground(Object... params)
        {

                  try {

                      JSONObject subscriptionResponse = CommonJsonParser.responseForSignin(uname, pwd).getJSONObject("response");

                        if (!(subscriptionResponse.equals(null))||!(subscriptionResponse.equals("")))  {                    


                        }


                    }



                  catch (NullPointerException e) {
                        // TODO Auto-generated catch block


                    }


                  catch (JSONException e) {
                        // TODO Auto-generated catch block
                    }


                  catch (Exception e) {
                        // TODO Auto-generated catch block
                    }

            return null;

        }


        @Override
        protected void onPostExecute(Object result) 
        {       
            if(progressDialog!=null){
            progressDialog.dismiss();
            }       

            super.onPostExecute(result);
        }

        @Override
        protected void onPreExecute() {

            progressDialog = ProgressDialog.show(SignInActivity.this, "", "Please wait");
            super.onPreExecute();
        }

    }

use AsyncTask.any server request or which takes long time should be written in background task