问题
User data in android 4.2 onwards is stored at /data/user/<userId>
But still I found /data/data directory in android 4.3 filesystem. I think it is there to store application data that is common for all users and /data/user/<userId> is used for storing user specific application data. Is this true?
回答1:
No.
/data/data always belongs to the primary user. You can see this by listing /data/user directory:
/data/user/0 is a soft-link to /data/data and the permissions are set so that only this "user 0" has access to all the data stored in /data/data.
Therefore /data/data is not common for all users.
来源：https://stackoverflow.com/questions/18464495/user-data-directory-in-android-4-3