AsyncTask ; doInbackground() not called after calling method onPreExecute()

Question

I did added async library at my project and checked already, I don't know why code flow doesn't go in to asynctask

Code

public void doMysql() {     Log.v("doMysql", "accessed");      new AsyncTask<Void, Void, String>() {         @Override         protected void onPreExecute() {             super.onPreExecute();             Log.e("AsyncTask", "onPreExecute");         }         @Override         protected String doInBackground(Void... params) {             Log.v("AsyncTask", "doInBackground");              String msg = "";              DefaultHttpClient httpclient = new DefaultHttpClient();             HttpPost httppost = new HttpPost("http://172.16.100.172:52273/mysql");              ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();              nameValuePairs.add(new BasicNameValuePair("myday", Integer.toString(day_picker.getYear()) +                      addZero(day_picker.getMonth() + 1) +                      addZero(day_picker.getDayOfMonth())));             nameValuePairs.add(new BasicNameValuePair("mystar", changeStar(day_picker.getMonth() + 1, day_picker.getDayOfMonth())));             nameValuePairs.add(new BasicNameValuePair("mybt", changeBloodType(blood_picker.getValue())));             nameValuePairs.add(new BasicNameValuePair("mynum", "" + myPhone.getText()));             nameValuePairs.add(new BasicNameValuePair("yournum", "" + partnerPhone.getText()));             nameValuePairs.add(new BasicNameValuePair("myregID", regid));             try {                 Log.v("setEntity", "before");                 httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));                 Log.v("setEntity", "after");              } catch (UnsupportedEncodingException e1) {                 Log.v("UnsupportedEncodingException", "");                 e1.printStackTrace();             }             //172.16.101.28             try {                   Log.v("post", "before");                 HttpResponse httpresponse = httpclient.execute(httppost);                 Log.v("post", "after");                 Log.v("HttpResponse ",httpresponse.getEntity().toString());             } catch (ClientProtocolException e) {                 Log.v("ClientProtocolException", "ClientProtocolException");                 e.printStackTrace();             } catch (IOException e) {                 Log.v("IOException", "IOException");                  e.printStackTrace();             }              return msg;         }         @Override         protected void onPostExecute(String msg) {             Log.v("AsyncTask", "onPostExecute");          }     }.execute(null, null, null); } 

I have a log statement in the code 'Log.v("AsyncTask", "doInBackground");'

But it doesn't show up in the logger 'Log.v("AsyncTask", "doInBackground");'

Answer 1

You should execute your task with executor

task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR); 

Because in lower versions of Android all AsyncTasks were executed at single background thread. So new tasks might be waiting, until other task working.

In lower versions in Android (actually on pre-HONEYCOMB) you can't execute AsyncTask on executor.

Change your code to

public void executeAsyncTask() {     AsyncTask<Void, Void, String> task = new AsyncTask<Void, Void, String>() {         @Override         protected void onPreExecute() {             super.onPreExecute();             Log.e("AsyncTask", "onPreExecute");         }          @Override         protected String doInBackground(Void... params) {             Log.v("AsyncTask", "doInBackground");             String msg = null;             // some calculation logic of msg variable             return msg;         }         @Override         protected void onPostExecute(String msg) {             Log.v("AsyncTask", "onPostExecute");         }     };      if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB/*HONEYCOMB = 11*/) {         task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);     } else {         task.execute();     } } 

Answer 2

Doing this not working for you?

task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR); 

I was already doing this and the problem was still there, the problem was I was using AsyncTask to run long background tasks that do run forever, so the ThreadPoolExecutor's worker threads were already occupied.

In my case AsyncTask.THREAD_POOL_EXECUTOR (use debugger to get your executor properties) was having the ff properties:

maximumPoolSize = 3 largetsPoolSize = 2 corePoolSize =2  

So disabling one of the long running asyncTasks made my doInBackground code to run but that is not the right solution.

The right solution is I moved long running tasks into custom threads rather than using AsyncTask.