Here is the sample code, which is working in Android Oreo and less than Oreo.
NotificationManager notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
NotificationCompat.Builder builder = null;
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
int importance = NotificationManager.IMPORTANCE_DEFAULT;
NotificationChannel notificationChannel = new NotificationChannel("ID", "Name", importance);
notificationManager.createNotificationChannel(notificationChannel);
builder = new NotificationCompat.Builder(getApplicationContext(), notificationChannel.getId());
} else {
builder = new NotificationCompat.Builder(getApplicationContext());
}
builder = builder
.setSmallIcon(R.drawable.ic_notification_icon)
.setColor(ContextCompat.getColor(context, R.color.color))
.setContentTitle(context.getString(R.string.getTitel))
.setTicker(context.getString(R.string.text))
.setContentText(message)
.setDefaults(Notification.DEFAULT_ALL)
.setAutoCancel(true);
notificationManager.notify(requestCode, builder.build());