GraphGymnastic

public class GraphGymnastic extends Application {
  final ExecutorService serv = Executors.newFixedThreadPool(2);
  public static void main(String argv[]) {
    launch(argv);
  }

  @Override public void start(Stage primaryStage) throws Exception {
    //Setup UI
    primaryStage.setTitle("Demo");
    final List<Node> nodesInGraph = new ArrayList<>();
    final FlowPane p = new FlowPane() {{
      setId("flowpane");
      getChildren().addAll(new Label("Label") {{
        setId("label");
      }}, new Button("Button") {{
        setId("button");
        // setOnMouseClicked(event -> handle(event, nodesInGraph)); //Uncomment and comment below to see effects!
        setOnMouseClicked(event -> handleAsync(event, nodesInGraph));
      }});
      setHgap(5);
    }};

    //Assume that this goes recursive and deep into a scene graph but still
    // returns a list
    //Here it takes the two childs for simplicity
    nodesInGraph.addAll(p.getChildrenUnmodifiable());

    //Show stage
    primaryStage.setScene(new Scene(p));
    primaryStage.show();
  }

  public void handle(MouseEvent ev, List<Node> nodesInGraph) {
    if (null != nodesInGraph)
      Platform.runLater(() -> nodesInGraph.forEach(node -> {
        //This will block the UI thread, so there is the need for a second
        //thread
        System.out.println(
            "Calculating heavy on node " + node.toString() + " with event from "
                + ev.getSource().toString());
        try {
          Thread.sleep(1000);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }));
  }

  public void handleAsync(MouseEvent ev, List<Node> nodesInGraph) {
    if (null != nodesInGraph)
      serv.submit(() -> nodesInGraph.forEach(node -> {
        //Now there is a second thread but it works on a LIVE view object
        // list, which is ugly
        //Option 1: Keep it like this, drawbacks? :S
        //Option 2: Copy the graph, costs performance... How deep should it
        // copy? :S
        System.out.println(
            "Calculating heavy on node " + node.toString() + " with event from "
                + ev.getSource().toString());
        try {
          Thread.sleep(1000);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }));
  }
}