Swing newbie, where are my button?

Question

I have these 3 classes, but my button dosn't show, why not?
Here the classes come, I have cut in them, so you wont se my variable defination, but I guess you will get the picture:
--- class # 1 ---
mainFrame = new JFrame("XCom v0.1");
cardPanel = new JPanel();
cardLayout = new CardLayout();
cardPanel.setLayout(cardLayout);
Enumeration enum = this.loadedModules.keys();
while(enum.hasMoreElements()) {
  String key = (String)enum.nextElement();
  SuperModule module = (SuperModule)this.loadedModules.get(key);
  cardPanel.add(module,module.getDescriptor("name"));
cardLayout.show(cardPanel,this.properties.getProperty("modules.currentModule"));
mainFrame.getContentPane().add(cardPanel,BorderLayout.CENTER);
mainFrame.pack();
mainFrame.setVisible(true);--- class #2 ---
public class SuperModule extends JPanel {
  private Hashtable descriptors = new Hashtable();
  public SuperModule() {
    super();
  public void addDescriptor(String key, String value) {
    descriptors.put(key,value);
  public String getDescriptor(String name) {
    return (String)this.descriptors.get(name);
}--- class #3 ---
public class Mail extends SuperModule {
  GridLayout gridLayout;
  JTextArea test;
  public Mail() {
    super();
    addDescriptor("name","Mail");
  public void init() {
    gridLayout = new GridLayout(1,1,10,10);
    this.setLayout(gridLayout);
    JButton button = new JButton("I'm a Swing button!");
    this.add(button);
}

Answer 1

Hi,
I am not able to see where u r creating an instance of the Class Mail (bcoz its there u have buttons ).Without creating instance of the class and adding to the cardlayout I don't see how u expect the buttons to be visible.
Nagaraj