If no action has been defined as default, a window of options opens.

如果没有指定默认的动作，则打开一个选项窗口。

youdao

By default, the action bar appears at the top of your activity window, slightly reducing the amount of space available for the rest of your activity's layout.

默认情况下，操作栏会出现在你的活动窗口的顶部，略有减少了可用空间为您的活动布局的其余部分的金额。

youdao

By default, the action bar appears at the top of your activity window, slightly reducing the amount of space available for the rest of your activity's layout.

默认情况下，操作栏会出现在你的活动窗口的顶部，略有减少了可用空间为您的活动布局的其余部分的金额。

youdao