[android] How to set default font family for entire Android app

With the release of Android Oreo you can use the support library to reach this goal.

  1. Check in your app build.gradle if you have the support library >= 26.0.0
  2. Add "font" folder to your resources folder and add your fonts there
  3. Reference your default font family in your app main style:

    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
       <item name="android:fontFamily">@font/your_font</item>
       <item name="fontFamily">@font/your_font</item> <!-- target android sdk versions < 26 and > 14 if theme other than AppCompat -->
    </style>
    

Check https://developer.android.com/guide/topics/ui/look-and-feel/fonts-in-xml.html for more detailed information.