StartingMQTT.java

MQTTHelper mqttHelper = new MQTTHelper(getApplicationContext());
mqttHelper.setCallback(new MqttCallbackExtended() {

  @Override
  public void connectComplete(boolean reconnect, String serverURI) {
     Log.d(TAG, "URI " + serverURI);
  }

  @Override
  public void connectionLost(Throwable cause) {
     cause.printStackTrace();
  }

  @Override
  public void messageArrived(String topic, MqttMessage message) throws Exception {
     String payload = new String(message.getPayload());
     LatLng currentLatLng = convertStringToLatLng(payload);
     Log.d(TAG, topic + " " + currentLatLng);
     latLngPublishRelay.accept(currentLatLng);
  }

  @Override
  public void deliveryComplete(IMqttDeliveryToken token) {
    Log.d(TAG, "Delivery complete");
  }
});