我创建了一个应用程序,我在其中实现了试用版代码。我的代码是
public class Test {
public static void main(String[] args) {
    int s = 2013;
    int t = 9;
    int u = 29;
    Calendar expireDate = Calendar.getInstance();
    expireDate.set(s,t,u);
    if (Calendar.getInstance().after(expireDate)) {
        JTextField username = new JTextField();
        JTextField password = new JPasswordField();         
        Object[] message = {
            "Username:", username,
            "Password:", password
        };
        int option = JOptionPane.showConfirmDialog(null, message, "Enter your Registration Code here", JOptionPane.OK_CANCEL_OPTION);
        if (option == JOptionPane.OK_OPTION) {
            String a ="as", b = "sa";
            if (username.getText().equals(a) && password.getText().equals(b)) {
                System.out.println("Login successful");
                JFrame frame = new JFrame("Test");
                frame.setVisible(true);
                frame.setSize(500, 200);
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                JPanel panel = new JPanel();
                frame.add(panel);
                JButton button = new JButton("hello agin1");
                panel.add(button);
                button.addActionListener(new Action1());
                JButton button2 = new JButton("hello agin2");
                panel.add(button2);
            } else {
                System.out.println("login failed");
                JOptionPane.showMessageDialog(null, "Not Valid");
            }
        } else {
            System.out.println("Login canceled");
            System.exit(1);
        }
    }else{      
    JFrame frame = new JFrame("Test");
    frame.setVisible(true);
    frame.setSize(500, 200);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panel = new JPanel();
    frame.add(panel);
    JButton button = new JButton("hello agin1");
    panel.add(button);
    button.addActionListener(new Action1());
    JButton button2 = new JButton("hello agin2");
    panel.add(button2);
}
}
static class Action1 implements ActionListener {
    public void actionPerformed(ActionEvent e) {
        System.exit(0);
    }
}
}
每次我在过期后打开应用程序时都必须注册。但我希望注册后不再寻找注册码。请帮忙。