code: public <V extends ViewGroup> void setTypeface(V viewGroup, String typefaceName, int style) {
  		int count = viewGroup.getChildCount();
  		for (int i = 0; i < count; i++) {
  			View child = viewGroup.getChildAt(i);
  			if (child instanceof ViewGroup) {
  				setTypeface((ViewGroup) child, typefaceName, style);
  				continue;
  			}
  			if (!(child instanceof TextView)) {
  				continue;
  			}
  			setTypeface((TextView) child, typefaceName, style);
  		}
  	}
docs: Set the typeface to the all text views belong to the view group.
  Note that this method recursively trace the child view groups and set typeface for the text views.
  @param viewGroup the view group that contains text views.
  @param typefaceName typeface name.
  @param style the typeface style.
  @param <V> view group parameter.