在线急求登录窗口密码验证有关问题

package cn.hdu.edu;import java.awt.BorderLayout;import java.awt.EventQueue;import javax.swing.JFrame;import javax.swing.JPanel;import javax.swing.border.EmptyBorder;import javax.swing.ButtonGroup;import javax.swing.JLabel;import javax.swing.JOptionPane;import javax.swing.JRadioButton;import javax.swing.JTextField;import javax.swing.JPasswordField;import javax.swing.JButton;import java.awt.event.ActionListener;import java.awt.event.ActionEvent;import java.awt.Color;import java.sql.*;public class Login extends JFrame {    private JPanel contentPane;    private JTextField textField;    private JPasswordField passwordField;    /**     * Create the frame.     */    public Login() {        setTitle("\u97F3\u50CF\u7BA1\u7406\u4FE1\u606F\u7CFB\u7EDF");        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        setBounds(100, 100, 480, 320);        contentPane = new JPanel();        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));        contentPane.setLayout(new BorderLayout(0, 0));        setContentPane(contentPane);                JPanel panel = new JPanel();        panel.setBackground(Color.CYAN);        contentPane.add(panel, BorderLayout.CENTER);        panel.setLayout(null);                JLabel label = new JLabel("\u767B\u5F55");        label.setBounds(200, 5, 44, 15);        panel.add(label);        ButtonGroup bgp = new ButtonGroup();        final JRadioButton rdbtnNewRadioButton = new JRadioButton("\u5458\u5DE5");        rdbtnNewRadioButton.setBackground(Color.CYAN);        rdbtnNewRadioButton.setBounds(145, 54, 58, 23);        panel.add(rdbtnNewRadioButton);                JRadioButton radioButton = new JRadioButton("\u5BA2\u6237");        radioButton.setBackground(Color.CYAN);        radioButton.setBounds(241, 54, 58, 23);        panel.add(radioButton);        bgp.add(radioButton);        bgp.add(rdbtnNewRadioButton);        JLabel label_1 = new JLabel("\u7528\u6237\u540D");        label_1.setBounds(136, 106, 54, 15);        panel.add(label_1);                textField = new JTextField();        textField.setBounds(189, 103, 170, 21);        panel.add(textField);        textField.setColumns(10);                JLabel label_2 = new JLabel("\u5BC6\u7801");        label_2.setBounds(136, 152, 39, 15);        panel.add(label_2);                passwordField = new JPasswordField();        passwordField.setBounds(189, 149, 170, 21);        panel.add(passwordField);                JButton btnNewButton = new JButton("\u767B\u5F55");        btnNewButton.addActionListener(new ActionListener() {            public void actionPerformed(ActionEvent e) {                if(rdbtnNewRadioButton.isSelected()){                     if (textField.toString().equals("")){                            JOptionPane.showMessageDialog(null, "请输入用户名", "温馨提示", JOptionPane.INFORMATION_MESSAGE);                        }                     else if (passwordField.toString().equals("")){                            JOptionPane.showMessageDialog(null, "请输入密码", "温馨提示", JOptionPane.INFORMATION_MESSAGE);                        }                         }                else{                    dispose();                    new KehuFrame().setVisible(true);                }                            }        });        btnNewButton.setBounds(110, 201, 93, 23);        panel.add(btnNewButton);                JButton button = new JButton("\u53D6\u6D88");        button.addActionListener(new ActionListener() {            public void actionPerformed(ActionEvent arg0) {                dispose();            }        });        button.setBounds(241, 201, 93, 23);        panel.add(button);    }    /**     * Launch the application.     */        public static void main(String[] args) {        EventQueue.invokeLater(new Runnable() {            public void run() {                try {                    Login frame = new Login();                    frame.setVisible(true);                } catch (Exception e) {                    e.printStackTrace();                }            }        });    }}