AnimatedTitle.java

import javafx.application.Platform;
import javafx.stage.Stage;
import javafx.stage.WindowEvent;

import java.util.Timer;
import java.util.TimerTask;

public class AnimatedTitle {

    public interface Animation {
        String animate(String title);

        static Animation marquee() {
            return title -> {
                if (title == null || title.length() < 2)
                    return title;
                else
                    return title.substring(1) + title.charAt(0);
            };
        }

        static Animation empty() {
            return title -> title;
        }
    }

    private final Stage stage;
    private final String title;
    private final Animation animation;
    private final long period;

    private final Timer timer;

    public AnimatedTitle(Stage stage, String title, Animation animation, long period) {
        if (stage == null)
            throw new IllegalArgumentException("Stage cannot be null");

        this.stage = stage;
        this.title = title == null ? "" : title;
        this.animation = animation == null ? Animation.empty() : animation;
        this.period = period <= 0 ? 256 : period;

        this.timer = new Timer(true);

        stage.addEventHandler(WindowEvent.WINDOW_CLOSE_REQUEST, windowEvent -> timer.cancel());
    }

    public void start() {
        stage.setTitle(title);
        timer.schedule(new TimerTask() {
            @Override
            public void run() {
                Platform.runLater(() -> {
                    stage.setTitle(animation.animate(stage.getTitle()));
                });
            }
        }, 0, period);
    }

    public void stop() {
        timer.cancel();
    }

    public void reset() {
        stop();
        stage.setTitle(title);
    }

    public String getOriginalTitle() {
        return title;
    }

    public String getCurrentTitle() {
        return stage.getTitle();
    }
}

Die Klasse gefällt mir aber ich würde tatsächlich den null check simpel halten dann erstellst du nicht jedes Mal ein Optional Objekt