dimens.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <integer name="weight_light">300</integer>
    <integer name="weight_regular">400</integer>
    <integer name="weight_semi_bold">600</integer>
    <integer name="weight_bold">700</integer>
    <integer name="weight_extra_bold">800</integer>
</resources>

open_sans.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"
    xmlns:tools="http://schemas.android.com/tools"
    tools:ignore="UnusedAttribute">

    <font
        android:font="@font/open_sans_light"
        android:fontStyle="normal"
        android:fontWeight="@integer/weight_light"

        app:font="@font/open_sans_light"
        app:fontStyle="normal"
        app:fontWeight="@integer/weight_light" />

    <font
        android:font="@font/open_sans_light_italic"
        android:fontStyle="italic"
        android:fontWeight="@integer/weight_light"

        app:font="@font/open_sans_light_italic"
        app:fontStyle="italic"
        app:fontWeight="@integer/weight_light" />

    <font
        android:font="@font/open_sans_regular"
        android:fontStyle="normal"
        android:fontWeight="@integer/weight_regular"

        app:font="@font/open_sans_regular"
        app:fontStyle="normal"
        app:fontWeight="@integer/weight_regular" />

    <font
        android:font="@font/open_sans_italic"
        android:fontStyle="italic"
        android:fontWeight="@integer/weight_regular"

        app:font="@font/open_sans_italic"
        app:fontStyle="italic"
        app:fontWeight="@integer/weight_regular" />

    <font
        android:font="@font/open_sans_semi_bold"
        android:fontStyle="normal"
        android:fontWeight="@integer/weight_semi_bold"

        app:font="@font/open_sans_semi_bold"
        app:fontStyle="normal"
        app:fontWeight="@integer/weight_semi_bold" />

    <font
        android:font="@font/open_sans_semi_bold_italic"
        android:fontStyle="italic"
        android:fontWeight="@integer/weight_semi_bold"

        app:font="@font/open_sans_semi_bold_italic"
        app:fontStyle="italic"
        app:fontWeight="@integer/weight_semi_bold" />

    <font
        android:font="@font/open_sans_bold"
        android:fontStyle="normal"
        android:fontWeight="@integer/weight_bold"

        app:font="@font/open_sans_bold"
        app:fontStyle="normal"
        app:fontWeight="@integer/weight_bold" />

    <font
        android:font="@font/open_sans_bold_italic"
        android:fontStyle="italic"
        android:fontWeight="@integer/weight_bold"

        app:font="@font/open_sans_bold_italic"
        app:fontStyle="italic"
        app:fontWeight="@integer/weight_bold" />

    <font
        android:font="@font/open_sans_extra_bold"
        android:fontStyle="normal"
        android:fontWeight="@integer/weight_extra_bold"

        app:font="@font/open_sans_extra_bold"
        app:fontStyle="normal"
        app:fontWeight="@integer/weight_extra_bold" />

    <font
        android:font="@font/open_sans_extra_bold_italic"
        android:fontStyle="italic"
        android:fontWeight="@integer/weight_extra_bold"

        app:font="@font/open_sans_extra_bold_italic"
        app:fontStyle="italic"
        app:fontWeight="@integer/weight_extra_bold" />
</font-family>