import javafx.application.Application;
import javafx.scene.layout.*;
import javafx.scene.*;
import javafx.scene.control.*;
import javafx.stage.Stage;
import javafx.scene.text.*;
import java.time.LocalTime;

public class Klokke extends Application {
    Text tekst = new Text(naa());

    @Override
    public void start(Stage stage) {
        VBox root = new VBox();
        root.getChildren().add(tekst);


        stage.setScene(new Scene(root, 200, 200));
        stage.show();

        new Thread(() -> {
            boolean slutt = false;
            while (!slutt) {
                tekst.setText(naa());
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    slutt = true;
                }
            }
        }).start();
    }

    private static String naa() {
        LocalTime t = LocalTime.now();
        return String.format("%02d:%02d:%02d", t.getHour(), t.getMinute(), t.getSecond());
    }
}