源代码如下：
1 package jpg; 2 3 import java.awt.BorderLayout; 4 import java.awt.EventQueue; 5 6 import javax.swing.JFrame; 7 import javax.swing.JPanel; 8 import javax.swing.border.EmptyBorder; 9 import javax.swing.JLabel; 10 import javax.swing.JOptionPane; 11 import javax.swing.JTextField; 12 import javax.swing.JButton; 13 import javax.swing.JComboBox; 14 import javax.swing.DefaultComboBoxModel; 15 import java.awt.event.ActionListener; 16 import java.awt.event.ActionEvent; 17 import javax.swing.ImageIcon; 18 import javax.swing.JPasswordField; 19 20 public class Day extends JFrame { 21 22 private JPanel contentPane; 23 private JTextField textField; 24 private JPasswordField passwordField; 25 26 public static void main(String[] args) { 27 28 Day frame = new Day(); 29 frame.setVisible(true); 30 31 } 32 33 34 public Day() { 35 36 setTitle("用户登录"); 37 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 38 setBounds(100, 100, 450, 300); 39 40 contentPane = new JPanel(); 41 contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); 42 setContentPane(contentPane); 43 contentPane.setLayout(null); 44 this.setResizable(false); 45 46 JLabel label = new JLabel("用户名"); 47 label.setBounds(39, 45, 54, 15); 48 contentPane.add(label); 49 50 JComboBox comboBox = new JComboBox(); 51 comboBox.setModel(new DefaultComboBoxModel(new String[] {"u7BA1u7406u5458 ", "u6536u94F6u5458"})); 52 comboBox.setBounds(126, 121, 173, 21); 53 contentPane.add(comboBox); 54 55 56 textField = new JTextField(); 57 textField.setBounds(126, 42, 173, 21); 58 contentPane.add(textField); 59 textField.setColumns(30); 60 61 JButton button = new JButton("确定"); 62 button.addActionListener(new ActionListener() { 63 public void actionPerformed(ActionEvent e) { 64 65 66 String userName=textField.getText(); 67 68 69 String passWord=String.valueOf( passwordField.getPassword()); 70 71 String role=(String)comboBox.getSelectedItem(); 72 73 if(userName==null||userName.length()<=0||passWord==null||passWord.length()<=0||role==null||role.length()<=0){ 74 JOptionPane.showMessageDialog(contentPane,"请输入完整登录信息！"); 75 } 76 else if(userName.equals("SMMS")&&passWord.equals("123456")&&role.equals("管理员")) 77 78 JOptionPane.showMessageDialog(contentPane,"欢迎登录SMMS超市购物系统！"); 79 80 else 81 JOptionPane.showMessageDialog(contentPane,"输入信息错误，请重新输入！"); 82 }}); 83 button.setBounds(142, 194, 77, 23); 84 contentPane.add(button); 85 86 JLabel label_1 = new JLabel("密码"); 87 label_1.setBounds(39, 88, 54, 15); 88 contentPane.add(label_1); 89 90 JLabel label_2 = new JLabel("角色"); 91 label_2.setBounds(39, 124, 54, 15); 92 contentPane.add(label_2); 93 94 passwordField = new JPasswordField(); 95 passwordField.setBounds(126, 85, 173, 21); 96 contentPane.add(passwordField); 97 98 JButton button_1 = new JButton("取消"); 99 button_1.setBounds(245, 194, 93, 23); 100 contentPane.add(button_1); 101 102 JLabel label_3 = new JLabel(""); 103 label_3.setIcon(new ImageIcon("C:\Users\lenovo.Lenovo-PC\Pictures\butterfly.jpg")); 104 label_3.setBounds(0, 0, 434, 261); 105 contentPane.add(label_3); 106 } 107 }
经审查发现以下问题：
1.代码格式不规范
26 public static void main(String[] args) { 27 28 Day frame = new Day(); 29 frame.setVisible(true); 30 31 } 32 33 34 public Day() { 35 36 setTitle("用户登录"); 37 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 38 setBounds(100, 100, 450, 300);
90 JLabel label_2 = new JLabel("角色"); 91 label_2.setBounds(39, 124, 54, 15); 92 contentPane.add(label_2);
修改后如下：
1 public static void main(String[] args) { 2 Day frame = new Day(); 3 frame.setVisible(true); 4 } 5 6 public Day() { 7 setTitle("用户登录"); 8 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 9 setBounds(100, 100, 450, 300);
90 JLabel label_2 =new JLabel("角色"); 91 label_2.setBounds(39, 124, 54, 15); 92 contentPane.add(label_2);
2.在复杂的条件表达式中，没有用括号清楚的表达逻辑的优先级
62 button.addActionListener(new ActionListener() { 63 public void actionPerformed(ActionEvent e) { 64 65 66 String userName=textField.getText(); 67 68 69 String passWord=String.valueOf( passwordField.getPassword()); 70 71 String role=(String)comboBox.getSelectedItem(); 72 73 if(userName==null||userName.length()<=0||passWord==null||passWord.length()<=0||role==null||role.length()<=0){ 74 JOptionPane.showMessageDialog(contentPane,"请输入完整登录信息！"); 75 } 76 else if(userName.equals("SMMS")&&passWord.equals("123456")&&role.equals("管理员")) 77 78 JOptionPane.showMessageDialog(contentPane,"欢迎登录SMMS超市购物系统！"); 79 80 else 81 JOptionPane.showMessageDialog(contentPane,"输入信息错误，请重新输入！"); 82 }});
修改后如下：
1 button.addActionListener(new ActionListener() { 2 public void actionPerformed(ActionEvent e) { 3 4 String userName = textField.getText(); 5 6 String passWord = String.valueOf(passwordField.getPassword()); 7 8 String role = (String) comboBox.getSelectedItem(); 9 10 if (userName == null || userName.length() <= 0 || passWord == null || passWord.length() <= 0 11 || role == null || role.length() <= 0) { 12 13 JOptionPane.showMessageDialog(contentPane, "请输入完整登录信息！"); 14 15 } else if (userName.equals("SMMS") && passWord.equals("123456") && role.equals("管理员")) 16 17 JOptionPane.showMessageDialog(contentPane, "欢迎登录SMMS超市购物系统！"); 18 19 else 20 JOptionPane.showMessageDialog(contentPane, "输入信息错误，请重新输入！"); 21 22 } 23 });
3.没有明确的注释代码的作用
34 public Day() { 35 36 setTitle("用户登录"); 37 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 38 setBounds(100, 100, 450, 300); 39 40 contentPane = new JPanel(); 41 contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); 42 setContentPane(contentPane); 43 contentPane.setLayout(null); 44 this.setResizable(false);
71 String role=(String)comboBox.getSelectedItem();
修改后如下：
34 public Day() { 35 // 窗体属性-给你的范围 36 setTitle("用户登录"); 37 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 38 setBounds(100, 100, 450, 300); 39 // 内容模板 40 contentPane = new JPanel(); 41 contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); 42 setContentPane(contentPane);// 重要 43 contentPane.setLayout(null);// 绝对布局 44 this.setResizable(false);// 面板的尺寸
71 String role = (String) comboBox.getSelectedItem();// 强制类型的转换
以上为个人意见，欢迎补充。