<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <item name="colorPrimary">#8BC34A</item>
        <item name="colorPrimaryDark">#7CB342</item>
    </style>

</resources>

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <item name="colorPrimary">#8BC34A</item>
        <item name="colorPrimaryDark">#7CB342</item>
        <item name="android:textViewStyle">@style/RobotoTextViewStyle</item>
        <item name="buttonStyle">@style/RobotoButtonStyle</item>
    </style>

    <!-- set global TextView font to Roboto light -->
    <style name="RobotoTextViewStyle" parent="android:Widget.TextView">
        <item name="android:fontFamily">sans-serif-light</item>
    </style>

    <!-- set global Button font to Roboto light -->
    <style name="RobotoButtonStyle" parent="android:Widget.Button">
        <item name="android:fontFamily">sans-serif-light</item>
    </style>
</resources>

Set global font to roboto
Set global font to roboto
