import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.Slider;
import javafx.scene.layout.Pane;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class SliderWithLabeledThumb extends Application {

    @Override
    public void start(Stage primaryStage) {
        Slider slider = new Slider();
        StackPane root = new StackPane(slider);
        root.setPadding(new Insets(20));

        Scene scene = new Scene(root);

        slider.applyCss();
        slider.layout();
        Pane thumb = (Pane) slider.lookup(".thumb");
        Label label = new Label();
        label.textProperty().bind(slider.valueProperty().asString("%.1f"));
        thumb.getChildren().add(label);


        primaryStage.setScene(scene);
        primaryStage.show();

    }

    public static void main(String[] args) {
        launch(args);
    }
}

public class MainViewController implements Initializable {

    @FXML private VBox root;
    private Slider timeSlider;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        timeSlider = new Slider();
        root.getChildren.add(timeSlider);
        timeSlider.setMax(360);
        timeSlider.setMin(0);
        timeSlider.setCursor(Cursor.OPEN_HAND);
        timeSlider.applyCss();
        timeSlider.layout();

        Pane thumb = (Pane) timeSlider.lookup(".thumb");
        Label label = new Label();
        label.textProperty().bind(timeSlider.valueProperty().asString("%.1f"));
        // the following line points to thumb, which is null then… (debugger proof)
        thumb.getChildren().add(label);
    }
}

public class Main extends Application {
    @Override
    public void start(Stage primaryStage) {
        try {
            FXMLLoader loader = new FXMLLoader();
            loader.setLocation(getClass().getResource("MainView.fxml"));
            Parent root = loader.load();
            Scene scene = new Scene(root,800,600);
            scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
            primaryStage.setScene(scene);
            primaryStage.show();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        launch(args);
    }
}