title: How to force Java FX scene refresh?
body: <p>I have an Java FX scene with a start button and several rectangles which represent the tiles of a map. I also have drawn a sphere which represents my explorer (it has to explore the map), but I am having difficulties with running the animation.</p>
  
  <p>In my OnMouseClicked handler for the start button, I start an algorithm for exploring the map which changes the position of the sphere and the colors of the tiles which have been visited. The problem is that the scene won't update itself while the algorithm is running, so I only get to see how the final scene will look like (after the algorithm has stopped running). How can I force a scene update so I can see all the color changes sequentially?</p>
  
  <p>Later edit:</p>
  
  <pre><code>import javafx.application.Application;
  import javafx.event.Event;
  import javafx.event.EventHandler;
  import javafx.event.EventType;
  import javafx.geometry.Insets;
  import javafx.scene.Group;
  import javafx.scene.Scene;
  import javafx.scene.control.Button;
  import javafx.scene.image.Image;
  import javafx.scene.layout.HBox;
  import javafx.scene.paint.Color;
  import javafx.scene.shape.Rectangle;
  import javafx.stage.Stage;
  
  public class Test extends Application {
  
  private static final double boxOuterSize = 50;
  private static final double boxInnerSize = 48;
  private static final double boxCornerRadius = 20;
  
  private Stage applicationStage;
  private Scene applicationScene;
  
  private static double   sceneWidth  = 1024;
  private static double   sceneHeight = 800;
  private static HBox     container = new HBox();
  private static Group    root = new Group();
  private Rectangle[] rectangles = new Rectangle[10];
  
  @Override
  public void start(Stage mainStage) throws Exception {
  
      applicationStage = mainStage;
      container.setSpacing(10);
      container.setPadding(new Insets(10, 10, 10, 10));
  
      try {
          applicationScene = new Scene(container, sceneWidth, sceneHeight);
          applicationScene.addEventHandler(EventType.ROOT,(EventHandler&lt;? super Event&gt;)this);
          applicationScene.setFill(Color.WHITE);
  
      } catch (Exception exception) {
          System.out.println ("exception : "+exception.getMessage());
      }
  
      applicationStage.setTitle("HurtLockerRobot - Tema 3 IA");
      applicationStage.getIcons().add(new Image("icon.png"));
      applicationStage.setScene(applicationScene);
  
      for(int i=0; i&lt;10; i++) {
          Rectangle r = new Rectangle();
          r.setFill(Color.BLUE);
          r.setX(i * boxOuterSize);
          r.setY(0);
          r.setWidth(boxInnerSize);
          r.setHeight(boxInnerSize);
          r.setArcHeight(boxCornerRadius);
          r.setArcWidth(boxCornerRadius);
          r.setSmooth(true);
          rectangles[i] = r;
          root.getChildren().add(rectangles[i]);
      }
  
      container.getChildren().add(root);
      Button startButton = new Button("Start");
      startButton.setOnMouseClicked(new EventHandler&lt;Event&gt;() {
          @Override
          public void handle(Event arg0) {
              for(int i=0; i&lt;10; i++) {
                  rectangles[i].setFill(Color.RED);
                  // TODO: some kind of scene refresh here
              }
          }
      });
      container.getChildren().add(startButton);
  
      applicationStage.show();
  }
  
  public static void main(String[] args) {
      launch(args);
  }
  }
  </code></pre>
  
  <p>Initially all the rectangles are blue. The behavior I want to obtain here is to see the rectangles changing colors sequentially. The problem is that I only get to see the end result (all the rectangles change their color at the same time).</p>