AndroidStudio中没有参考文档

昨天突然出现了一个新问题.当我将鼠标悬停在方法上或按下Ctrl-Q时,我曾经获得该特定方法的文档信息.

但现在我得到了(按下Ctrl-Q键SharedPreferences.getLong()):

Following external urls were checked:
            http://developer.android.com/reference/android/content/SharedPreferences.html#getLong-java.lang.String-long-
            http://developer.android.com/reference/android/content/SharedPreferences.html#getLong(java.lang.String, long) 

    The documentation for this element is not found. Please add all the needed paths to API docs in Project Settings.
        android.content.SharedPreferences
        public abstract long getLong(String s, long l)

我google了很多,但找不到答案.我需要添加哪些路径以及在哪里？

您必须从SDK Manager下载Android SDK的文档