JavaFX: prosty stoper cyfrowy

Klasa Listing14c_03

package rozdzial14c;

import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.beans.property.BooleanProperty;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.ToggleButton;
import javafx.scene.layout.*;
import javafx.scene.paint.Color;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
import javafx.stage.Stage;

import java.time.Instant;
import java.time.Duration;

public class Listing14c_03 extends Application {
    private static final Font CLOCK_FONT =
            Font.font("Arial", FontWeight.BOLD, 20);
    private static final Background CLOCK_BACKGROUND =
            new Background(new BackgroundFill(Color.HONEYDEW,
            CornerRadii.EMPTY, new Insets(0, 0, 0, 0)));
    private Label label;
    private ToggleButton tbutton;
    private AnimationTimer timer;

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

    @Override
    public void start(Stage stage) {

        try {
            VBox root = new VBox();
            label = new Label();
            label.setText("00:00:00");
            label.setFont(CLOCK_FONT);
            label.setTextFill(Color.GREEN);
            timer = new AriaTimer();
            tbutton = new ToggleButton("Start");
            BooleanProperty sel = tbutton.selectedProperty();
            sel.addListener((observable, oldValue, newValue) -> {
                tbutton.setText(newValue ? "Stop" : "Start");
                if (newValue) {
                    timer = new AriaTimer();
                    timer.start();
                } else {
                    timer.stop();
                }
            });
            root.setBackground(CLOCK_BACKGROUND);
            root.getChildren().addAll(label, tbutton);
            Scene scene = new Scene(root, 200, 50);
            stage.setScene(scene);
            stage.setTitle("Stoper Cyfrowy");
            stage.setOnCloseRequest(event -> Platform.exit());
            stage.show();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private class AriaTimer extends AnimationTimer {
        final Instant start = Instant.now();

        @Override
        public void handle(long now) {
            Instant end = Instant.now();
            long millis = (Duration.between(start, end)).toMillis();
            long second = (millis / 1000) % 60;
            long milli = millis - second * 1000;
            long minute = (millis / (60000)) % 60;
            long hour = millis / (3600000);
            String time = String.format("%02d:%02d:%02d.%d",
                    hour, minute, second, milli);
            label.textProperty().set(time);
        }
    }
}
Po uruchomieniu klasy, uruchomieniu i zatrzymaniu stopera zobaczymy (Rys. 14_04)