android - Progress Dialog not show on screen -

i edited code according dear mayank'answer not show message sended input in displaymsg() method before method begines..i should methodtest() started nfc , in method onnewintent(intent intent)

@override protected void onnewintent(intent intent) {    methodtest();     ..............  }  public void methodtest() {     displaymsg("method 1 running");     method1();      displaymsg("method 2 running");     method2();      displaymsg("method 3 running");     method3();  }  private int displaymsg(string msg) {     totalmsg += msg;     displaymsgclass dc = new displaymsgclass();     dc.doinbackground(totalmsg); }  private class displaymsgclass extends asynctask<string, integer, string> {      @override     protected void onpreexecute() {          textview.settext("hello !!!");         progressbar = (progressbar) findviewbyid(r.id.progressbar1);         progressbar.setvisibility(view.visible);         super.onpreexecute();     }      @override     protected void onprogressupdate(integer... values) {         super.onprogressupdate(values);      }      @override     protected string doinbackground(string... messages) {           return messages[0];     }      @override     protected void onpostexecute(string result) {         progressbar.setvisibility(view.invisible);          textview.settext(result);     } } 

in layout:

<linearlayout> <progressbar     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:visibility="gone"     android:id="@+id/progressbar1"     />  <textview   android:layout_width="wrap_content"   android:layout_height="wrap_content"   android:id="@+id/textv1"   android:hint="appletpass"   android:gravity="center"/>  </linearlayout> 

remember asynctasks should ideally used short operations (a few seconds @ most.)

try learn more asynctask , there many mistakes in code

1. do not call doinbackground() manually.

   dc.doinbackground(totalmsg); // error

2. displaymsg() called several times, each time new instance of class displaymsgclass created

   displaymsgclass dc = new displaymsgclass(); // error

3. onpreexecute()
textview.settext("hello !!!"); // nullpointerexception. textview.settext() called without initializing it.

caution

do not call asynctask.execute() more 1 on same intance.
eg:

displaymsgclass displaymsgclass = new displaymsgclass();   displaymsgclass.execute();   displaymsgclass.execute(); //error, illegalstateexception   

will show basic demo based on implementation , can modify according own way.

public void methodtest() {      // execute task     new displaymsgclass().execute("download now"); }  /* public void methodtest() {     displaymsg("method 1 running");     method1();      displaymsg("method 2 running");     method2();      displaymsg("method 3 running");     method3();  }  private int displaymsg(string msg) {     totalmsg += msg;     displaymsgclass dc = new displaymsgclass();     dc.doinbackground(totalmsg); } */  private class displaymsgclass extends asynctask<string, integer, string> {      @override     protected void onpreexecute() {         super.onpreexecute();          // retrieve widgets         progressbar = (progressbar) findviewbyid(r.id.progressbar1);         textview = (textview) findviewbyid(r.id.textv1);           textview.settext("download initialized");         progressbar.setvisibility(view.visible);     }      @override     protected void onprogressupdate(integer... values) {         super.onprogressupdate(values);     }      @override     protected string doinbackground(string... messages) {          // read commands         string command = messages[0];         try {             thread.sleep(2000);         } catch (interruptedexception e) {             e.printstacktrace();         }         return "download completed";     }      @override     protected void onpostexecute(string result) {          //invoked on ui thread after background computation finishes         progressbar.setvisibility(view.invisible);         textview.settext(result);     } }