android - Changing ProgressBar visibility from inside onClick -

my activity_main.xml contains progressbar, starts hidden ("gone")

<progressbar        android:id="@+id/progressbar_sendingphonenumber"        style="?android:attr/progressbarstylelarge"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@id/button_sendphonenumber"        android:layout_centerinparent="true"        android:visibility="gone" /> 

and mainactivity.java has this,
onclick handler button have

    final context context = this;      sendphonenumberbutton.setonclicklistener(new onclicklistener() {          @override         public void onclick(view arg0) {              progressbar progressbar = (progressbar) findviewbyid(r.id.progressbar_sendingphonenumber);             progressbar.setvisibility(view.visible);              // simulate http connection             try {                 thread.sleep(3000);             } catch (interruptedexception e) {                 // todo auto-generated catch block                 e.printstacktrace();             }              progressbar.setvisibility(view.gone);              // redirect new activity             intent intent = new intent(context, inboxactivity.class);             startactivity(intent);         }     }); 

the problem progress bar never shown, although onclick code executed (eg. redirected new activity @ end). line:

progressbar.setvisibility(view.visible); 

isn't taking effect.

i think has context, , trying change visibility of progressbar "outside" activity, i'm not sure.

how can solve this?

it never shown because calling

try {     thread.sleep(3000);  } catch (interruptedexception e) {    // todo auto-generated catch block    e.printstacktrace();   } 

that makes "sleep" thread responsible draw same progressbar trying show