Android中ActionBar中显示overflow

//force to show overflow menu in actionbar for android 4.4 below

    private void getOverflowMenu() {

         try {

            ViewConfiguration config = ViewConfiguration.get(this);

            Field menuKeyField = ViewConfiguration.class.getDeclaredField("sHasPermanentMenuKey");

            if(menuKeyField != null) {

                menuKeyField.setAccessible(true);

                menuKeyField.setBoolean(config, false);

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

    }