Implementation Prerequisites - Learn OpenGL ES: For Mobile Game and Graphics Development - page 48

super.onCreate(savedInstanceState);
Button button = new Button(this);
button.setText("SETCONTENTVIEW");
setContentView(button);
}
Note Layout widgets, such as LinearLayout, as well as the
widgets with visual representation, such as Button, ( Listing 2-4 )
are all subclasses of the android.view.View class.