Failed to post notification on channel “null” Target Api is 26

Question

Two log showing

1: Use of stream types is deprecated for operations other than volume control

2: See the documentation of setSound() for what to use instea

Answer 1

Gulzar Bhat's answer is working perfectly if your minimum API is Oreo. If your minimum is lower however, you have to wrap the NotificationChannel code in a platform level check. After that you can still use the id, which will be ignored pre Oreo:

if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
    int importance = NotificationManager.IMPORTANCE_LOW;
    NotificationChannel notificationChannel = new NotificationChannel(NOTIFICATION_CHANNEL_ID, NOTIFICATION_CHANNEL_NAME, importance);
    notificationChannel.enableLights(true);
    notificationChannel.setLightColor(Color.RED);
    notificationChannel.enableVibration(true);
    notificationChannel.setVibrationPattern(new long[]{100, 200, 300, 400, 500, 400, 300, 200, 400});
    notificationManager.createNotificationChannel(notificationChannel);
}

NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(context, NOTIFICATION_CHANNEL_ID);

NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
notificationManager.notify((int)(System.currentTimeMillis()/1000), mBuilder.build());