Question

I try to run in JavaFX application background thread periodically, which modifies some GUI property.

I think I know how to use Task and Service classes from javafx.concurrent and can’t figure it out how to run such periodic task without using Thread#sleep() method. It would be nice if I can use some Executor from Executors fabricate methods (Executors.newSingleThreadScheduledExecutor())

I tried to run Runnable every 5 sec, which restarts javafx.concurrent.Service but it hangs immediately as service.restart or even service.getState() is called.

So finally I use Executors.newSingleThreadScheduledExecutor(), which fires my Runnable every 5 sec and that Runnable runs another Runnable using:

Platform.runLater(new Runnable() {
 //here i can modify GUI properties
}

It looks very nasty 🙁 Is there a better way to do this using Task or Service classes?

Answer 1

You can use Timeline for that task:

Timeline fiveSecondsWonder = new Timeline(
                 new KeyFrame(Duration.seconds(5), 
                 new EventHandler<ActionEvent>() {

    @Override
    public void handle(ActionEvent event) {
        System.out.println("this is called every 5 seconds on UI thread");
    }
}));
fiveSecondsWonder.setCycleCount(Timeline.INDEFINITE);
fiveSecondsWonder.play();

for the background processes (which don’t do anything to the UI) you can use old good java.util.Timer:

new Timer().schedule(
    new TimerTask() {

        @Override
        public void run() {
            System.out.println("ping");
        }
    }, 0, 5000);