code: public static <T extends View> T findViewById(Activity act, int viewId) {
      View containerView = act.getWindow().getDecorView();
      return findViewById(containerView, viewId);
    }
docs: This method returns the reference of the View with the given Id in the layout of the
  Activity passed as parameter
  
  @param act    The Activity that is using the layout with the given View
  @param viewId The id of the View we want to get a reference
  @return The View with the given id and type