连数据库,输入用户名和密码后如何跳转到主窗口

import javax.swing.*; import java.awt.event.*; import java.sql.*; public class Login extends JFrame implements ActionListener { private JLabel lbId, lbPass; private JTextField txtId, txtPass; private JButton btLogin, btExit; private Connection datacon = null;//连接对象 private PreparedStatement pstat = null;//命令对象 private ResultSet rs = null;//结果