MainActivity.kt

@SuppressLint("NewApi")
private fun adjustToolbarMarginForNotch() { 
    // Notch is only supported by >= Android 9
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
        val windowInsets = window.decorView.rootWindowInsets
        if (windowInsets != null) {
            val displayCutout = windowInsets.displayCutout
            if (displayCutout != null) {
                 val safeInsetTop = displayCutout.safeInsetTop
                 val newLayoutParams = toolbar.layoutParams as ViewGroup.MarginLayoutParams
                 newLayoutParams.setMargins(0, safeInsetTop, 0, 0)
                 toolbar.layoutParams = newLayoutParams
            }
        }
    }
}