JavaFX 2 busy indicator cursor

Question

I'm trying to change the cursor to indicate that the program is busy. It seems like this should be pretty simple, but I haven't been able to get it to work correctly and after searching for several hours, I haven't come up with the solution. Here's what I'm trying to do.

public class ButtonTest extends Application {
  @Override
  public void start(Stage primaryStage) {
    final StackPane root = new StackPane();
    primaryStage.setScene(new Scene(root, 200, 150));

    Button button = new Button();
    button.setText("Button");
    root.getChildren().add(button);

    primaryStage.show();

    button.setOnAction(new EventHandler<ActionEvent>() {
      @Override
      public void handle(ActionEvent event) {
        // Set the cursor to the wait cursor.
        root.setCursor(Cursor.WAIT);
        // Do some work.
        try {
          Thread.sleep(5000);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
        // Set the cursor back to the default.
        root.setCursor(Cursor.DEFAULT);
      }

    });
}

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

If I comment out the setCursor(Cursor.DEFAULT), after I press the button it waits 5 seconds then changes the cursor to the wait cursor. So it seems like it waiting until after the sleep, then executing setCursor(Cursor.WAIT), immediately followed by the setCursor(Cursor.DEFAULT). What am I missing?

See related: [JAVAFX:How to disable button for specific time?](http://stackoverflow.com/q/16919727) — Uluk Biy, Jun 24 '13 at 16:58

score 3 · Answer 1 · answered Jun 24 '13 at 17:01

3

You're sleeping the main UI thread which is the same thread that's supposed to change the cursor shape. You need to kick off your sleep (or whatever expensive operation) on a background thread, while the main UI thread exits the handle method and returns to the UI event loop so that the cursor change can become active.

answered Jun 24 '13 at 17:01

Thanks for the response. I've tried the following, but it doesn't work either. I have very little experience with threads, am I doing something wrong? – Tim Fletcher Jun 26 '13 at 17:10
Oops, hit enter too soon. I create a thread, start the thread, set the wait cursor, join the thread and the reset the cursor. But it still doesn't work. – Tim Fletcher Jun 26 '13 at 17:38
Don't join the thread! Just let the handler return. You must reset the cursor from inside the background thread method, via cross-thread invocation to the UI thread. – Jun 26 '13 at 17:58

score 1 · Answer 2 · answered Jun 02 '14 at 21:02

Have you ever tried Platform.runLater for this:

It should work like this:

primaryStage.getScene().setCursor(Cursor.WAIT);
Platform.runLater(new Runnable() {
  @Override
  public void run() {
    doSomethingInteresting();
    primaryStage.getScene().setCursor(Cursor.DEFAULT);
  }
});

The idea here is simple: in the original event just the mouse shape is defined and a new event is scheduled which will perform the action directly after this.

JavaFX 2 busy indicator cursor

2 Answers2