I am currently building a Radio App for Android Auto and I simply want to send a notification to the screen when a song gets requested.

I’m trying to send a CarToast but it requires a CarContext:

CarToast.makeText(**CARCONTEXT**, "Song requested!", CarToast.LENGTH_SHORT).show()

My problem is that I can’t easily access the CarContext because I have a Media App using an extended MediaBrowserServiceCompat class. In there I haven’t found a way to access the CarContext. Normally I could get the CarContext when I create a CarAppService, but I don’t know how I could make a Media App with the CarAppService. There is no documentation for something like this at all.

I also tried sending a normal notification using the NotificationCompatBuilder:

private fun createNotificationChannel() {
    // Create the NotificationChannel, but only on API 26+ because
    // the NotificationChannel class is not in the Support Library.
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        val name = "My Radio"
        val descriptionText = "My Radio Notifications"
        val importance = NotificationManager.IMPORTANCE_DEFAULT
        val channel = NotificationChannel(CHANNEL_ID, name, importance).apply {
            description = descriptionText
        }
        // Register the channel with the system.
        val notificationManager: NotificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
        notificationManager.createNotificationChannel(channel)
    }
}

fun sendNotification(message: String) {
    println("Sending notification: $message")
    var builder = NotificationCompat.Builder(context, CHANNEL_ID)
        .setSmallIcon(R.drawable.ic_custom_search)
        .setContentTitle("My Radio")
        .setContentText(message)
        .setPriority(NotificationCompat.PRIORITY_DEFAULT)

    with(NotificationManagerCompat.from(context)) {
        if (ActivityCompat.checkSelfPermission(
                context,
                Manifest.permission.POST_NOTIFICATIONS
            ) != PackageManager.PERMISSION_GRANTED
        ) {
            return@with
        }

        var notificationId = (0..10000).random()
        notify(notificationId, builder.build())
    }

This works fine for sending a normal notification to the phone but it won’t get displayed on the head unit.

Is there any way to access the CarContext in the MediaBrowserServiceCompat or is there any other way to send a notification in Android Auto?