How to connect custom font in android?

Question

Android

Greetings!
Tell me how to connect fonts in an Android application.
There is an application consisting of buttons. Text on buttons. You need to write it in a custom font.
Next, see the screenshots of what I tried:
Explain what I'm wrong. On the Internet it was possible to find only semi-finished knowledge similar to this, unfortunately.

Answer 1

The site treacherously refuses to load screenshots. Here are links to them:
prnt.sc/8x0awi
prnt.sc/8x0avb

Answer 2

The assets folder should be in Project\app\src\main\
prntscr.com/8x16ri

Answer 3

In the markup file, fontView is Button, in the code you look for it as TextView
Next, most likely you need a lot of buttons, implement your button, which will contain the fonts you need, so as not to play like this for each button in the code, but it's up to you