How to handle a async API call in gluon javafx Application

How to login with a REST API server from gluon mobile application. I have tried HttpClient which does able to call .

To access a REST API you can use RestClient.

     import com.gluonhq.connect.provider.RestClient;

     RestClient restClient = RestClient.create()
         .host("http://myhost.com")
         .path("restservice/login")
         .queryParam("username","myname")
         .queryParam("password","myencodedpassword")
         .method("GET");
     GluonObservableObject<User> sample = DataProvider.retrieveObject(restClient.createObjectDataReader(User.class));

To then handle the result you can use the stateProperty

    sample.stateProperty().addListener((obv,ov,nv)->{
         if(nv.equals(ConnectState.SUCCEEDED)){
             User loggedInUser = sample.get();
         }
    });

you can use initializedProperty as well.

RestClient JavaDoc