Are there any side-effects of using multiple string.xml files?
There may be negligible side effects in performance, you can add as much as you can. I have 3 activity files MainActivity, PhotoActivity, UserActivity, create a common strings.xml file and other activity related files.
-strings.xml -> create common string values here.
--strings_main.xml -> create main activity specific string values here.
--strings_photo.xml -> ...
--strings_user.xml -> ... etc etc
Hope this is helpful. Thanks!
As stated in the documentation you can use whatever filename you want:
The filename is arbitrary. The <string> element's name will be used as the resource ID.