Using Thread.sleep to get waiting effect in JavaFX

Question

I want to achieve something like this: user press the login button and then label shows: "Connecting."
0.5 sec time interval
"Connecting.."
0.5 sec time interval
"Connecting..."
etc

Just a visual effect that indicates something is actually going on "under the hood".

All I managed to get wasn't quite what I was expecting. I click the button, wait 1.5 sec and then I got "Connecting...", missing 2 previous steps.

First, my Status class

public class Status {
    private static StringProperty status = new SimpleStringProperty();

    public static void setStatus(String newStatus) {
        status.setValue(newStatus);
    }

    public static String getStatus() {
        return status.getValue();
    }

    public static StringProperty get() {
        return status;
    }
}

and my LoginView class

public class LoginView extends Application {

   private Button loginButton = new Button("Log in");
   private Label statusLabel;

   private void createLabels() {        
      statusLabel = new Label(Status.getStatus());
      statusLabel.textProperty().bind(Status.get());
   }

}  

 private void createButtons() {        
        loginButton.setOnAction(e -> {
            try {
                Status.setStatus("Connecting.");
                Thread.sleep(500);
                Status.setStatus("Connecting..");
                Thread.sleep(500);
                Status.setStatus("Connecting...");
                Thread.sleep(500);
            } catch (InterruptedException e1) {
                e1.printStackTrace();
            }
        });
    }

Use `Timeline`: https://stackoverflow.com/questions/9966136/javafx-periodic-background-task — SedJ601, Feb 03 '18 at 14:13

score 2 · Answer 1 · answered Feb 03 '18 at 14:34

Run a Task from a different thread. Task allows you to update it's message property on the JavaFX application thread that should be used to update the GUI and must not be blocked by long-running tasks, since it's responsible for rendering:

Task<Void> task = new Task<Void>() {

    @Override
    protected Void call() throws InterruptedException {
        updateMessage("Connecting.");
        Thread.sleep(500);
        updateMessage("Connecting..");
        Thread.sleep(500);
        updateMessage("Connecting...");
        Thread.sleep(500);

        return null;
    }

};

// bind status to task's message
Status.get().bind(task.messageProperty());

// run task on different thread
new Thread(task).start();

score 1 · Answer 2 · answered Feb 03 '18 at 14:11

You should do animations with the Timeline API. Have a look here:

https://docs.oracle.com/javase/8/javafx/api/javafx/animation/Timeline.html

Basically you just define KeyFrames at 0.5 seconds distance and set the value of the text to add a another dot. You can also make it repeat indefinitely until the connection is established to get cyclic animation.

Another way is to make a SequentialTransition which will have two PauseTransitions of 0.5 seconds.

BTW in your code you pause the main UI thread and that is why you can’t see the animation.

Using Thread.sleep to get waiting effect in JavaFX

2 Answers2