Clock demo

To demonstrate the topics covered in this chapter, I have written a small clock application.

It will become more complex with each upcoming chapter; for the first release it just shows a current local time in text form and updates it every second, demonstrating Stage/Scene usage, one of the layout managers, and the Application FX Thread workflow:

See the inline comments for details about the program:

// chapter1/clock/ClockOne.java
public class ClockOne extends Application {
    // we are allowed to create UI objects on non-UI thread
    private final Text txtTime = new Text();
        
    private volatile boolean enough = false;
        
    // this is timer thread which will update out time view every second
    Thread timer = new Thread(() -> {
        SimpleDateFormat dt = new SimpleDateFormat("hh:mm:ss");
        while(!enough) {
            try {
                // running "long" operation not on UI thread
                Thread.sleep(1000);
            } catch (InterruptedException ex) {}
            final String time = dt.format(new Date());
            Platform.runLater(()-> {
                // updating live UI object requires JavaFX App Thread
                txtTime.setText(time);
            });
        }
    });

    @Override
    public void start(Stage stage) {
        // Layout Manager
        BorderPane root = new BorderPane();
        root.setCenter(txtTime);
        
        // creating a scene and configuring the stage
        Scene scene = new Scene(root, 200, 150);        
        stage.initStyle(StageStyle.UTILITY);
        stage.setScene(scene);
        
        timer.start();
        stage.show(); 
    }
    
    // stop() method of the Application API
    @Override
    public void stop() {
        // we need to stop our working thread after closing a window 
        // or our program will not exit
        enough = true;
    }

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