Swing Create Loader in Thread non blocking GUI

Question

I have kind of a problem with showing loader during a heavy data loading by main program. Below there is a class called SplashScreen which displays .gif animation of loader.

public class SplashScreen extends JWindow {

public SplashScreen() {
    super();
    Image image = Toolkit.getDefaultToolkit().getImage(getClass().getResource("/resources/load.gif"));
    try {
        if (image != null) {
            JLabel imageLabel = new JLabel();
            imageLabel.setIcon(new ImageIcon(image));
            this.getContentPane().setLayout(new BorderLayout());
            this.getContentPane().add(imageLabel, BorderLayout.CENTER);
            this.pack();
            Dimension screenSize =
                    Toolkit.getDefaultToolkit().getScreenSize();
            Dimension labelSize = imageLabel.getPreferredSize();
            setLocation(screenSize.width / 2 - (labelSize.width / 2),
                    screenSize.height / 2 - (labelSize.height / 2));
            addMouseListener(new MouseAdapter() {
                public void mouseClicked(MouseEvent e) {
                    dispose();
                }
            });
            addKeyListener(new KeyAdapter() {
                public void keyTyped(KeyEvent e) {
                    dispose();
                }
            });
        }
    } catch (Exception ex) {
    }
}

There is a result of running this piece of code :

Loader gif

But when I would like to load a lot of data (say 1 milion records) I have something like this :

Loader gif blank

I was using Thread, EventQueue.invokeLater and SwingUtilities to show SplashScreen in separate Thread, but it doesn't work. It is always blank when I load heavy data. Unfortunately, I must say that using EventQueue or SwingUtilities is quite difficult, because of you are not able to end tasks started by those utilities.

invokeLater will execute the runnable, at some time in the future, with the context of the EDT, that's the point. Instead, try running your blocking code in a SwingWorker instead — MadProgrammer, Feb 03 '15 at 08:56

score 1 · Answer 1 · answered Feb 04 '15 at 11:50

I finally figured out how to properly implement this case.

1) Implement SplashScreen which will display loader (.gif)

    public class SplashScreen extends JWindow {

        public SplashScreen() {
            super();
            Image image = Toolkit.getDefaultToolkit().getImage(getClass().getResource("/resources/load.gif"));
            try {
                if (image != null) {
                    JLabel imageLabel = new JLabel();
                    imageLabel.setIcon(new ImageIcon(image));
                    this.getContentPane().setLayout(new BorderLayout());
                    this.getContentPane().add(imageLabel, BorderLayout.CENTER);
                    this.pack();
                    Dimension screenSize =
                            Toolkit.getDefaultToolkit().getScreenSize();
                    Dimension labelSize = imageLabel.getPreferredSize();
                    setLocation(screenSize.width / 2 - (labelSize.width / 2),
                            screenSize.height / 2 - (labelSize.height / 2));
                    addMouseListener(new MouseAdapter() {
                        public void mouseClicked(MouseEvent e) {
                            dispose();
                        }
                    });
                    addKeyListener(new KeyAdapter() {
                        public void keyTyped(KeyEvent e) {
                            dispose();
                        }
                    });
                }
            } catch (Exception ex) {
            }
        }

        @Override
        public void dispose() {
            setVisible(false);
        }
}

2) Init ScheduledExecutorService

ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();

3) Implement Thread responsible for showing SplashScreen

Thread splashThread = new Thread(new Runnable() {
            public void run() {
                setSplashScreen(new SplashScreen());
                getSplashScreen().setVisible(true);
                getSplashScreen().toFront();
                getSplashScreen().setAlwaysOnTop(true);
            }
        });

4) Schedule new created Thread

executor.schedule(splashThread, 0, TimeUnit.MILLISECONDS);

5) When there is a need to dispose SplashScreen

getSplashScreen().dispose();

Additionally you can create separate Thread to check if there is a need to dispose SplashScreen.

private void invokeExecutor() {
    executor.scheduleAtFixedRate(new DoneTask(), 0, 200, TimeUnit.MILLISECONDS);
}

private class DoneTask implements Runnable {
    @Override
    public void run() {
        if (fileWorker.isDone()) { //SwingWorker
            getSplashScreen().dispose();
        }
    }
}

Swing Create Loader in Thread non blocking GUI

1 Answers1