How do I specify eg. Roboto-Medium or Roboto-Black in styles.xml

Question

Posts like this How to change fontFamily of TextView in Android suggests, that the variants of Roboto fonts you can specify in styles.xml in Android 4.2 boils down to the follow

Answer 1

On Android 5.0 you can set Roboto Medium with sans-serif-medium.

This solution, taken from Google iosched 2014, uses sans-serif on Android pre-v21:

values/styles.xml

values/fonts.xml

sans-serif

values-v21/fonts.xml

sans-serif-medium