title: json is null in makeHttpRequest call in Android
body: <p>I have a java web project named ConnectionToOracle . I have a servlet named Sign_Up_Servlet there . </p>
  
  <p>So I have the following code : </p>
  
  <pre><code> private static String url_sign_up_execute
                  = "http://10.11.201.84:8084//ConnectionToOracle/Sign_Up_Servlet"; 
  
  private class GetSignUpStatus extends AsyncTask&lt;String, Integer, String&gt; {
  
  
          ProgressDialog pDialog = new ProgressDialog(Sign_Up.this);
  
          @Override
          protected void onPreExecute() {
              // TODO Auto-generated method stub
              super.onPreExecute();
              pDialog.setMessage("Please wait...");
              pDialog.show(); 
          }
  
          @Override
          protected void onPostExecute(String result) {
              // TODO Auto-generated method stub
              super.onPostExecute(result);
  
  
              pDialog.dismiss();
  
              if (json == null) {
                  pDialog.dismiss();
                  Toast.makeText(
                          getApplicationContext(),
                          "Unable to Perform Your Request.Server Is Temporarily  Unreachable! Please Try Later.",
                          Toast.LENGTH_LONG).show();
              } 
              else{
                  if(pErrorFlag.equals("N"))
                      Toast.makeText(getApplicationContext(),"Sign Up successfully done ", Toast.LENGTH_LONG).show();
                  else if( pErrorFlag.equals("Y") )
                      Toast.makeText(getApplicationContext(), pErrorMessage, Toast.LENGTH_LONG).show();
              }   
          }
  
          @Override
          protected String doInBackground(String... args) {
              // TODO Auto-generated method stub
  
              List&lt;NameValuePair&gt; params = new ArrayList&lt;NameValuePair&gt;(); 
  //          params.add(new BasicNameValuePair("pDeviceId",deviceId_str));   
  //          params.add(new BasicNameValuePair("pMobileNo",mobile_no_str)); 
  //          params.add(new BasicNameValuePair("pUserId",user_id_str)); 
  //          params.add(new BasicNameValuePair("pPassword",password_str)); 
  //          params.add(new BasicNameValuePair("pPinCode",pin_code_str));
  
  //          params.add(new BasicNameValuePair("pDeviceId","1"));   
  //          params.add(new BasicNameValuePair("pMobileNo","1")); 
  //          params.add(new BasicNameValuePair("pUserId","1")); 
  //          params.add(new BasicNameValuePair("pPassword","1")); 
  //          params.add(new BasicNameValuePair("pPinCode","1"));
  //          
              json = jsonParser.makeHttpRequest(url_sign_up_execute, "POST", params);
  
              // Log.d("All Login Responese: ", json.toString());
  
              try {
                  if (json != null) {
                      jsonArray = json.getJSONArray(TAG_SIGN_UP);
                      for (int i = 0; i &lt; jsonArray.length(); i++) {
                          JSONObject c = jsonArray.getJSONObject(i);
  
                          pErrorFlag = c.getString(TAG_ERROR_FLAG);
                          pErrorMessage = c.getString(TAG_ERROR_MESSAGE) ;
  
                      }
                      // Log.d("error Code", errorCode);
                  } else {
                       Log.d("Server Unreachable",
                       "Unable to Perform Your request.Server Is Unreachable! Please Try Later.");
                  }
              } catch (JSONException e) {
                  // TODO Auto-generated catch block
                  e.printStackTrace();
              }
  
              return null;
          }
      }
  </code></pre>
  
  <p>I am making a http request to "<a href="http://10.11.201.84:8084//ConnectionToOracle/Sign_Up_Servlet" rel="nofollow">http://10.11.201.84:8084//ConnectionToOracle/Sign_Up_Servlet</a>" url . But I am getting json value null . Why ? How can I resolve this error ? </p>