JTabbedPaneのタブにJProgressBarを表示

private final Executor executor = Executors.newCachedThreadPool();
public void addTab(String title, final Component content) {
  super.addTab(title, new JLabel("Loading..."));
  final JProgressBar bar = new JProgressBar();
  final int currentIndex = getTabCount() - 1;
  final JLabel label = new JLabel(title);
  Dimension dim = label.getPreferredSize();
  int w = Math.max(80, dim.width);
  label.setPreferredSize(new Dimension(w, dim.height));
  Insets tabInsets = UIManager.getInsets("TabbedPane.tabInsets");
  bar.setPreferredSize(new Dimension(w, dim.height - tabInsets.top - 1));
  setTabComponentAt(currentIndex, bar);
  SwingWorker worker = new SwingWorker() {
    @Override public Object doInBackground() {
      int current = 0;
      int lengthOfTask = 180;
      while (current < lengthOfTask) {
        if (!bar.isDisplayable()) return "NotDisplayable";
        try {
          Thread.sleep(25);
        } catch (InterruptedException ie) {
          return "Interrupted";
        }
        current++;
        setProgress(100 * current / lengthOfTask);
      }
      return "Done";
    }

    @Override public void done() {
      setTabComponentAt(currentIndex, label);
      setComponentAt(currentIndex, content);
    }
  };
  worker.addPropertyChangeListener(new ProgressListener(bar));
  executor.execute(worker); // JDK 1.6.0_18
  // worker.execute();
}