android - AlertDialog setmessage not working inside Asynctask -

below code trying display progress in asyntask via onprogressupdate method aint showing in alert diaalog. initial message shown.

 class downloadfilefromurl extends asynctask<string, string, string> {          private alertdialog.builder alert;         private int progress = 0;         /**          * before starting background thread show progress bar dialog          */         @override         protected void onpreexecute() {             super.onpreexecute();             alert = new alertdialog.builder(context);             alert.settitle("downloading..");             alert.setmessage("1");             alert.setcancelable(false);             alert.show();         }          /**          * downloading file in background thread          */         @override         protected string doinbackground(string... f_url) {             int count;             try {                 url url = new url(f_url[0]);                 urlconnection conection = url.openconnection();                 conection.connect();                  // useful can show tipical 0-100%                 // progress bar                 int lenghtoffile = conection.getcontentlength();                  // download file                 inputstream input = new bufferedinputstream(url.openstream(),                         8192);                  // output stream                 outputstream output = new fileoutputstream(file);                  byte data[] = new byte[1024];                  long total = 0;                  while ((count = input.read(data)) != -1) {                     total += count;                     // publishing progress....                     // after onprogressupdate called                     publishprogress("" + (int) ((total * 100) / lenghtoffile));                      // writing data file                     output.write(data, 0, count);                 }                  // flushing output                 output.flush();                  // closing streams                 output.close();                 input.close();              } catch (exception e) {                 log.e("error: ", e.getmessage());             }              return null;         }          /**          * updating progress bar          */         @override         protected void onprogressupdate(string... progress) {             log.d("myapp","progress :"+progress[0]);             alert.setmessage(""+progress[0]);         }          /**          * after completing background task dismiss progress dialog          **/         @override         protected void onpostexecute(string file_url) {             // dismiss dialog after file downloaded } } 

as have written log show progress update in onprogressupdate, log printed alert.setmessage in onprogressupdate seems not set message alert dialog.

as per code, alert alertdialog.builder , not alertdialog itself. raised concern me because reason might not changing because showed builder, not give alertdialog. tried out simple code:

public class mainactivity extends appcompatactivity {      private alertdialog.builder alert;     private alertdialog ad;      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);          alert = new alertdialog.builder(this);         alert.settitle("downloading..");         alert.setmessage("1");         alert.setcancelable(false);         ad = alert.show();           log.d("sample", "set message 2");         alert.setmessage("2");          log.d("sample", "set message 3");         ad.setmessage("3");     }  } 

at first, used alert.setmessage (this alertdialog.builder), , message did not change @ all. after putting in alertdialog , setting message of alertdialog instance, message changed. care try approach out. pass alertdialog.builder alertdialog first then, setmessage using alertdialog instance.

docs alertdialog , alertdialog.builder.

hope helps somehow. luck. :)