android - Getting TextView view object from "onCreate" Activity's method -

i'm having trouble on trying retrieve textview object id inside oncreate method activity.

my activity's xml fragment textview's section:

<textview     android:id="@+id/message_display_field"     android:layout_width="fill_parent"     android:layout_height="wrap_content" /> 

the oncreate method:

protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_display_message);      if (savedinstancestate == null) {         getfragmentmanager().begintransaction()                 .add(r.id.container, new placeholderfragment()).commit();     }      intent intent = getintent();     string message = intent.getstringextra(mainactivity.extra_message);      // create text view     textview tv = (textview) findviewbyid(r.id.message_display_field);     tv.settext(message); } 

textview tv = (textview) findviewbyid(r.id.message_display_field); not return textview expect return null instead

finally 1 expect, throws nullpointerexception.

then how retrieve textview view object if not way go ? :(

notes :

• there no warnning or error before press run button launch application through emulator.

• nullpointer fired @ runtime.

i appriciate help, thank in advance !

actually if textview inside fragment xml u have :

1- go class fragment override oncreateview method there view inside fragment so.

textview foo;as //globle var  @override public view oncreateview(layoutinflater inflater, viewgroup container,             bundle savedinstancestate) {         view rootview = inflater.inflate(r.layout.fragment_main, container,                 false);      foo = rootview.findviewbyid(r.id.message_display_field);      return rootview;                  } 

now happy
hope helps