Android O - Single line Notification - like the “Android System - USB charging this device”

Question

I would like to have an ongoing notification for my ForegroundService that requires as small place as possible. I like the "Android System - USB charging t

Answer 1

To display a compact single line notification like the charging notification, you have to create a Notification Channel with priority to IMPORTANCE_MIN.

@TargetApi(Build.VERSION_CODES.O)
private static void createFgServiceChannel(Context context) {
   NotificationChannel channel = new NotificationChannel("channel_id", "Channel Name", NotificationManager.IMPORTANCE_MIN);
   NotificationManager mNotificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
   mNotificationManager.createNotificationChannel(channel);
}

And then create an ongoing notification like that:

public static Notification getServiceNotification(Context context) {
   NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(context, "channel_id");
   mBuilder.setContentTitle("One line text");
   mBuilder.setSmallIcon(R.drawable.ic_notification);
   mBuilder.setProgress(0, 0, true);
   mBuilder.setOngoing(true);
   return mBuilder.build();
}

NOTE

Please note that I've tested it with an IntentService instead of a Service, and it works. Also I've just checked setting a Thread.sleep() of 15 seconds and the notification is showing perfectly until the IntentService stops itself.

There are some images (sorry some texts are in Spanish, but I think the images are still useful):

And if you drag down and opens the notification, it's shown as follows:

EXTRA

If you notice that Android System shows a notification indicating all apps which are using battery (apps with ongoing services), you can downgrade the priority of this kind of notifications and it will appear as one line notifications like the charging notification.

Take a look at this:

Just long click on this notification, and select ALL CATEGORIES:

And set the importance to LOW:

Next time, this "battery consumption" notification will be shown as the charging notification.