android - How to code more than 2 ...extends AsyncTask .doInBackground() onPostExecute() within an Activity -

by time android apps onstart(),it execute httprequesttask. have done part , works fine.

after apps open , display data,needs click on submit button post data spring rest web service.in mind,i think might need write extends asynctask ,doinbackground , onpostexecute

what should code system differentiate extends asynctask ,doinbackground , onpostexecute within same activity?

protected void onstart(){     super.onstart();     new httprequesttask().execute(); }    private class httprequesttask extends asynctask<void, void, arraylist<item>> {      @override     protected arraylist<item> doinbackground(void... params) {     //....some code   }  @override     protected void onpostexecute(arraylist<pickeritemdetail> pickerlist) {     //.....come code , logic  }  }