android中invalidateOptionsMenu()的用法 [英] What is the use of invalidateOptionsMenu() in android

问题描述

当我浏览导航抽屉的示例代码时，我是android的新手，我发现他调用了invalidateOptionsMenu()方法，因此我搜索了其功能，但找不到答案，因此任何人都可以向我简要介绍一下其功能以及何时应该使用它.

I am a newbie to android when I am going through a sample code for navigation drawer I found he called the method invalidateOptionsMenu() so I searched regarding its functionality but couldn't find an answer so can anyone please brief me its functionality and whenshould we use that.

推荐答案

此函数告诉android应该重绘菜单.默认情况下，一旦创建菜单，就不会在每一帧都重新绘制菜单(因为这样一遍又一遍地重新绘制同一菜单是没有用的.)

This function tell android that it should redraw the menu. By default, once the menu is created, it won't be redrawn every frame (since that would be useless to redraw the same menu over and over again).

在选项菜单中进行了某些更改(添加元素，删除元素或更改文本)时，应调用此函数.这样，android将知道是时候重新绘制菜单，您的更改才会出现.

You should call this function when you changed something in the option menu (added an element, deleted an element or changed a text). This way android will know that it's time te redraw the menu and your change will appear.

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