I am trying to do a application-wide font change and creating a style file to do so. In this file (below) I just want to change typeface value of TextAppearance style of And
Instead of assets folder, you can put the .ttf file on fonts folder. To use fonts support in XML feature on devices running Android 4.1 (API level 16) and higher, use the Support Library 26+. Right click res folder, new -> Android resource directory-> select font -> Ok. put your "myfont.ttf" file in newly created font folder.
On res/values/styles.xml add,
On layout file add android:textAppearance="@style/customfontstyle",
Refer : https://developer.android.com/guide/topics/ui/look-and-feel/fonts-in-xml