看来安卓4.0提供的安卓的layoutDirection作为的LinearLayout和的Andr​​oid版本：textDirection作为TextView的，但是当我选择他们，我得到一个编译错误它不承认他们这样的：

it seems that android 4 provides "android:layoutDirection" for linearLayout and "android:textDirection" for textView , but when i choose them , i get a compilation error that it doesn't recognize them like that:

错误：未找到属性的layoutDirection在包资源标识符'机器人'

我也无法了解这些属性在互联网上的更多信息。它们意味着什么，以及为什么我不能用呢？

i also can't find out more information on the internet about those attributes. what do they mean, and how come i can't use them?

推荐答案

，如果你改变你的项目属性，以API级别17工作。

It works if you change your project properties to API Level 17.