android: How to use asyncTask in Rest Web service?


I am creating apps in android in that I have login logout activity, Multilistview activity which data coming from rest web service. here problem is that when calling webservice from login activity I get error the networkonmainthreadexception then i searched on goggle about that exception, somebody said on stack overflow use AsyncTask in your code for seperation thread and I implemented asynctask in my code but not working. i am totally confusing how to use asynctask and I want to add asynctask in following code. I provide code without asynctask which i did. can anybody to help me how to exactly use asynctask when calling webservice.

following is the get data from edit text call function

UserFunctions userFun = new UserFunctions(); if ((username.trim().length() > 0)&&(userpsw.trim().length() > 0)) { JSONObject json = userFun.loginUser(username, userpsw); . . .

following is the function class

public JSONObject loginUser(String userEmail, String userPsw) { List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", login_tag)); params.add(new BasicNameValuePair("email", userEmail)); params.add(new BasicNameValuePair("password", userPsw)); JSONObject json = jsonParser.getJsondataFromUrl(params); //Log.d("tag", json.toString()); return json; }

following is the actual webservice class

public void getJsondataFromUrl(List<NameValuePair> params) { { DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); httpPost.setEntity(new UrlEncodedFormEntity(params)); HttpResponse httpResp = httpClient.execute(httpPost); HttpEntity httpEntity = httpResp.getEntity(); inStream = httpEntity.getContent(); //Log.d(tag, inStream.toString()); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { BufferedReader bufferReader = new BufferedReader(new InputStreamReader (inStream, "iso-8859-1"), 8); StringBuilder strBuilder = new StringBuilder(); String line = null; while ((line = bufferReader.readLine()) != null) { strBuilder.append(line + "n"); } inStream.close(); json = strBuilder.toString(); //Log.d("JSON", json); } catch (Exception e) { e.printStackTrace(); } // try parse the string to a JSON object try { jsonObj = new JSONObject(json); } catch (JSONException e) { e.printStackTrace(); } return jsonObj;*/ }

Thanks in advance


Create a class that inherit from AsyncTask. In doInBackground call your network code and return a POJO. In postExecute, update your views using this POJO. Follow the signature of AsyncTask's method to understand how to type your sublcass with generics.

You should also consider this thread : <a href="https://stackoverflow.com/a/13147992/693752" rel="nofollow">https://stackoverflow.com/a/13147992/693752</a> AsyncTask is not really the best tool to create network requests on Android.


@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.login); context=this; Log.v(TAG+"onCreate", "OnCreate Called"); username = (EditText)findViewById(R.id.editText_user); password = (EditText)findViewById(R.id.editText_psw); btngo = (ImageButton)findViewById(R.id.imageButton_go); btngo.setOnClickListener(this); } @Override public void onClick(View v) { Log.v(TAG+"onClick", "onClick Called"); if(v== btngo) { user=username.getText().toString().trim(); psw=password.getText().toString().trim(); dialog = ProgressDialog.show(context, "", "Please! Wait...",true); GetResult result = new GetResult(); result.execute(); } } } private class GetResult extends AsyncTask<String, Void, String> { @Override protected String doInBackground(String... urls) { Log.v(TAG + ".doInBackground", "doInBackground method call"); String response1 = null; HttpClient httpclient = new DefaultHttpClient(); HttpPost httppost = new HttpPost("url"); // Log.d("response", "WORKING"); try { List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(); nameValuePairs.add(new BasicNameValuePair("webservice", "1")); nameValuePairs.add(new BasicNameValuePair("Email_ID", user)); nameValuePairs.add(new BasicNameValuePair("Password",psw)); httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); HttpResponse response = httpclient.execute(httppost); InputStream is = response.getEntity().getContent(); WebHelper webHelper = new WebHelper(); response1 = webHelper.convertStreamToString(is); Log.v(TAG+".doInBackground", "json response is:" + response1); } catch (ClientProtocolException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } return response1; } @Override protected void onPostExecute(String result) { Log.v(TAG + ".onPostExecute", "onPostExecute method call"); dialog.dismiss(); Log.v(TAG+".onPostExecute", "json response is:" + result); /* Intent intent= new Intent(LoginActivity.this, ChoiceExamActivity.class); startActivity(intent); */ if(result!=null){ try { //JSONTokener tokener = new JSONTokener(result); JSONObject resultObjct = new JSONObject(result); String user_id=resultObjct.getString("User_ID"); if(user_id.equalsIgnoreCase("0")) { ExamUtil.showAlert(LoginActivity.this,"Incorrect User name or password"); } else { String firstname = resultObjct.getString("First_Name"); Log.v(TAG+".onPostExecute", "user id is:" + user_id); Log.v(TAG+".onPostExecute", "firstname is:" + firstname); Intent intent= new Intent(LoginActivity.this, ChoiceExamActivity.class); startActivity(intent); } } catch (JSONException e) { e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); } } else{ ExamUtil.showAlert(LoginActivity.this,"We have some problem in processing request, try again."); } } } }


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