显示jFileChooser时出现NullPointerException

我用以下代码段显示了一个jFileChooser:

public File getDestination() {
    JFileChooser chooser = new JFileChooser();
    chooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
    int option = chooser.showSaveDialog(null);
    if(option == JFileChooser.APPROVE_OPTION) {
        return chooser.getSelectedFile().getAbsolutePath();
    }
    return new File(".");
}

通常,第一次显示时,它会正确显示和工作。第二次,它总是抛出这个异常:

Exception in thread "Basic L&F File Loading Thread" java.lang.NullPointerException
    at sun.awt.shell.Win32ShellFolder2.pidlsEqual(Unknown Source)
    at sun.awt.shell.Win32ShellFolder2.equals(Unknown Source)
    at sun.awt.shell.Win32ShellFolderManager2.isFileSystemRoot(Unknown Source)
    at sun.awt.shell.ShellFolder.isFileSystemRoot(Unknown Source)
    at javax.swing.filechooser.FileSystemView.isFileSystemRoot(Unknown Source)
    at javax.swing.filechooser.WindowsFileSystemView.isTraversable(Unknown Source)
    at javax.swing.JFileChooser.isTraversable(Unknown Source)
    at javax.swing.plaf.basic.BasicDirectoryModel$LoadFilesThread.run0(Unknown Source)
    at javax.swing.plaf.basic.BasicDirectoryModel$LoadFilesThread.run(Unknown Source)

Java版本说明:

java version "1.6.0_20"
Java(TM) SE Runtime Environment (build 1.6.0_20-b02)
Java HotSpot(TM) Client VM (build 16.3-b01, mixed mode, sharing)

我找到的线头 here 说我应该降级Java版本。我应该听从他们的建议,还是我有什么错的地方?