Error Trying To Change Font Android Studio

I am trying to change the font of a TextView programatically in android studio, ive followed some tutorials closely but it keeps giving me errors and was just wondering if anyone h

Solution 1:

It wasn't working because I was doing the code part in the onCreate, even though i was actually using fragments, so I just deleted the fragment and went back to using the normal activity and its working now.

thanks for the help.