public void run() throws MqttException { // register MQTT and connect publisher = new Messenger(CLIENT_ID + "Pub", publisherCallBack()); subscriber = new Messenger(CLIENT_ID, subscriberCallBack()); subscriber.connect(); // subscribe to all required topics try { subscriber.subscribe("RouteList"); subscriber.subscribe("Monitor/#"); // messenger.subscribe("Call/Floor/#"); // messenger.subscribe("Call/Hall/#"); } catch (MqttException e) { e.printStackTrace(); } }