stramek

    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
        <item name="fontFamily">@font/abril_fatface</item>
    </style>

stramek

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
    <item name="fontFamily">@font/abril_fatface</item>
</style>

stramek

<application
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme">
    <!-- rest of content -->
</application>

stramek

val fonts = listOf("Abril Fatface", "Acme", "Aguafina Script", "Aldrich",
        "Almendra SC", "Architects Daughter", "Arizonia", "Audiowide", "Baloo")

stramek

fun createFontRequest(fontName: String) = FontRequest(
        "com.google.android.gms.fonts",
        "com.google.android.gms",
        fontName,
        R.array.com_google_android_gms_fonts_certs)

stramek

val callback = object : FontsContractCompat.FontRequestCallback() {

    override fun onTypefaceRetrieved(typeface: Typeface?) {
        textCode.typeface = typeface
    }

    override fun onTypefaceRequestFailed(reason: Int) {
        Log.i("MainActivity", "onTypefaceRequestFailed with code: " + reason)
    }
}

stramek

changeFontButton.setOnClickListener {
    FontsContractCompat.requestFont(applicationContext, createFontRequest(fonts[nextFontIndex]), callback, Handler())
}