How to use specified weights for fonts in XML

Its looks like android following web standards for font management and sizing for android app.

The “font-weight” property is used to define the weight of a font, such as regular or bold.

But for all other weights a numerical range from 100 to 900 is used. One of the challenges with web fonts is that most web browsers do not properly support font weights other than normal & bold. The following chart describes the possible mappings of weights to the numeric definitions:

100    Thin (Hairline)
200    Extra Light (Ultra Light)
300    Light
400    Normal (Regular)
500    Medium
600    Semi Bold (Demi Bold)
700    Bold
800    Extra Bold (Ultra Bold)
900    Black (Heavy)
950    Extra Black (Ultra Black)

You can read more about font weight here

cc_montserrat_bold.xml

<?xml version="1.0" encoding="utf-8"?>
<font-family xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <font
        android:font="@font/montserrat_bold"
        android:fontStyle="normal"
        android:fontWeight="700"
        app:font="@font/montserrat_bold"
        app:fontStyle="normal"
        app:fontWeight="700" />
    <font
        android:font="@font/montserrat_bolditalic"
        android:fontStyle="italic"
        android:fontWeight="700"
        app:font="@font/montserrat_bolditalic"
        app:fontStyle="italic"
        app:fontWeight="700" />

</font-family>

cc_montserrat_regular.xml

<?xml version="1.0" encoding="utf-8"?>
<font-family xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <font
        android:font="@font/montserrat_regular"
        android:fontStyle="normal"
        android:fontWeight="400"
        app:font="@font/montserrat_regular"
        app:fontStyle="normal"
        app:fontWeight="400" />
    <font
        android:font="@font/montserrat_italic"
        android:fontStyle="italic"
        android:fontWeight="400"
        app:font="@font/montserrat_italic"
        app:fontStyle="italic"
        app:fontWeight="400" />


</font-family>

Kotlin Usage:

val textView = dialog.findViewById<TextView>(android.R.id.message) as TextView
val typeface = ResourcesCompat.getFont(context,R.font.cc_montserrat_regular)
        textView.typeface = typeface

Android Project Screenshot: