如何使用show方法

在JPanel 里面放了3個按鈕，默認的是顯示最前面添加的那個按鈕，可以是我想他顯示添加的第二個按鈕。怎么使用show來切換到第二個按鈕，讓它顯示出來呢？
    public class Text extends JFrame implements ActionListener{
    public Text() {
    this.setSize(400, 350);
    this.setLocation(200, 100);
    Container c = this.getContentPane();
    c.setLayout(new GridLayout(3, 3));
    JPanel jp1 = new JPanel();
    jp1.setLayout(new CardLayout(3,1));
    jp1.setBorder(BorderFactory.createTitledBorder("注意這里"));
    JButton jb1 = new JButton("按鈕1");
    jb1.setMargin(new Insets(0, 0, 0, 0));
    jp1.add(jb1, "aa");
    jb1.addActionListener(this);
    JButton jb2 = new JButton("按鈕2");
    jb2.setMargin(new Insets(0, 0, 0, 0));
    jp1.add(jb2, "bb");
    jb2.addActionListener(this);
    JButton jb3 = new JButton("按鈕3");
    jb3.setMargin(new Insets(0, 0, 0, 0));
    jp1.add(jb3, "cc");
    jb3.addActionListener(this);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    c.add(jp1);
    }
    public static void main(String[] args) {
    new Text().setVisible(true);
    }
    public void actionPerformed(ActionEvent e) {
    JButton btn = (JButton) e.getSource();
    CardLayout card = (CardLayout) btn.getParent().getLayout();
    card.next(btn.getParent());
    }
    }