JWindowを使ったSplash Screenの表示

private JWindow splashScreen;
private JLabel  splashLabel;
public MainPanel() {
  super();
  createSplashScreen(SPLASH_PATH);
  EventQueue.invokeLater(new Runnable() {
    @Override public void run() {
      showSplashScreen();
    }
  });
  // 実行時間の長い処理など
  try {
    Thread.sleep(3000);
  } catch (InterruptedException e) {
    System.out.println(e);
  }
  EventQueue.invokeLater(new Runnable() {
    @Override public void run() {
      showPanel();
      hideSplash();
    }
  });
}

public void createSplashScreen(String path) {
  ImageIcon img = new ImageIcon(getClass().getResource(path));
  splashLabel = new JLabel(img);
  splashScreen = new JWindow(getFrame());
  splashScreen.getContentPane().add(splashLabel);
  splashScreen.pack();
  splashScreen.setLocationRelativeTo(null);
}

public void showSplashScreen() {
  splashScreen.setVisible(true);
}

public void hideSplash() {
  splashScreen.setVisible(false);
  splashScreen = null;
  splashLabel = null;
}

public JFrame getFrame() {
  return frame;
}

public void showPanel() {
  this.setPreferredSize(new Dimension(300, 200));
  frame.getContentPane().add(this);
  frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
  frame.pack();
  frame.setLocationRelativeTo(null);
  frame.setVisible(true);
}