java signalr don't receive message when app is closed

I'm using SignalR. I can receive Messages and show Notification when the app is open or is in the background. but when closed application I can't receive messages. Does anyone have a solution to this?

I have the following code in MainActivity OnCreate:

ActivityChat.connection.received(json -> runOnUiThread(new Runnable() {
            @RequiresApi(api = Build.VERSION_CODES.O)
            public void run() {

                JsonObject jsonObject = json.getAsJsonObject();
                if (jsonObject != null && jsonObject.has("A")) {
                    jsonArray = jsonObject.getAsJsonArray("A");
                    String method = jsonObject.get("M").getAsString();
                    //PushNotifications(method,jsonArray);
                    if (method.equals("addNewMessage")) {
                        if (jsonArray != null && jsonArray.size() != 0) {
                            if (jsonArray.get(2).getAsString().equals(driverID)) {
                                if (TransportClass.showCaseView != null && !TransportClass.showCaseView.isShowing()) {
                                    Notificate();
                                }
                            }
                        }
                    }
                }
            }
        }));

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