Java SE (Java Platform, Standard Edition)

I have a issue how to display content from a JavaFX Task. Tested this code which displays result from Task:

Task<VBox> task = new Task<VBox>()
                {
                    @Override
                    protected VBox call() throws Exception
                    {
                        TabContentInfrastructure content = new TabContentInfrastructure();


                        return content.initTestTabContentData();
                    }
                };
                task.run();

                VBox vb = new VBox();

                //GetDailySalesService service = new GetDailySalesService();

                //Task<VBox> task = new GetDailySalesTask();

                Region veil = new Region();
                veil.setStyle("-fx-background-color: rgba(0, 0, 0, 0.4)");
                veil.setPrefSize(240, 160);
                ProgressIndicator p = new ProgressIndicator();
                p.setMaxSize(140, 140);

                //p.progressProperty().bind(service.progressProperty());
                veil.visibleProperty().bind(task.runningProperty());
                p.visibleProperty().bind(task.runningProperty());
                //vb.visibleProperty().bind(service.runningProperty().not());
                //tableView.itemsProperty().bind(service.valueProperty());

                StackPane stack = new StackPane();

                //stack.getChildren().addAll(content.initTestTabContentData(), veil, p);
                System.out.println("service.valueProperty() = " + task.valueProperty());


                task.setOnSucceeded(new EventHandler<WorkerStateEvent>()
                {
                    @Override
                    public void handle(WorkerStateEvent t){

                        System.out.print("Entered setOnSucceeded**********" + t.getSource().getValue());
                        stack.getChildren().clear();
                        stack.getChildren().addAll(task.getValue());


                    }
                });

                stack.getChildren().addAll(veil, p);

                tabdata.setContent(stack);

Using the above code when I click on a tree node to load object the entire application freezes for 1-2 second then I see the progress bar and finally the VBox content.

When I update the code this way:

new Thread(task).start(); 

in order to start the heavy VBox content initialization I get null as result but the performance is very smooth.

The big question is how I can display the result from the Task into the GUI after the task is completed?