FCM notification message are not received in android Oreo version?

Question

I have send FCM notification from server to users. It works fine(until api 25) but in Oreo when the application have not in background(services are closed) (or) completely close

Answer 1

private void generateNotification(String message, String title) {

    Intent intent = new Intent(getApplicationContext(), ActitivtyNotification.class);
    intent.setFlags(Intent.FLAG_ACTIVITY_PREVIOUS_IS_TOP);
    NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

    Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
    NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
            .setSmallIcon(R.drawable.stkfood_logo)  //a resource for your custom small icon
            .setContentTitle(title) //the "title" value you sent in your notification
            .setContentText(message) //ditto
            .setAutoCancel(true)  //dismisses the notification on click
            .setSound(defaultSoundUri);

    //Setting up Notification channels for android O and above
    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
        int importance = NotificationManager.IMPORTANCE_HIGH;
        NotificationChannel notificationChannel = new NotificationChannel("3", "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});
        assert mNotificationManager != null;
        notificationBuilder.setChannelId("3");
        mNotificationManager.createNotificationChannel(notificationChannel);
    }
    PendingIntent contentIntent = PendingIntent.getActivity(this, 3, intent, PendingIntent.FLAG_UPDATE_CURRENT);
    notificationBuilder.setContentIntent(contentIntent);
    mNotificationManager.notify(3, notificationBuilder.build());
}