private void setListener(ViewGroup group) {
                View[] childViews = getChildViews(group);
                for (View view : childViews) {
                        if (view instanceof Button) {
                                view.setListener(this);
                                // ViewGroup일경우는 재귀호출 한다!
                        } else if (view instanceof ViewGroup) {
                                setListener((ViewGroup) view);
                        }
                }
        }

여기서                 for (View view : childViews) {

이거 뭔뜻이냐?