何时以及多久为ActionBar调用onPrepareOptionsMenu()方法？

Question

很明显Activities- 在显示菜单之前调用该方法.但是什么ActionBar时候总是显示出来？如何触发它被动态更新menuItems？

Answer 1

使用invalidateOptionsMenu()来触发文档建议的onPrepareOptionMenu()方法.

On Android 3.0 and higher, you must call invalidateOptionsMenu() when you want to update the menu, because the menu is always open. The system will then call onPrepareOptionsMenu() so you can update the menu items.