Question

我正在为程序创建一个登录窗口。我无法让我的程序搜索我的arraylist并返回用户名然后再次搜索密码。

    public class Login extends JFrame {

    public String firstName, lastName, account, birthYear, password;
    Login(String fn, String ln, String acc, String by, String pw){
        firstName = fn;
        lastName = ln;
        account = acc;
        birthYear = by;
        password = pw;
    }
    Login current;

    ArrayList<Login> list= new ArrayList<Login>();
    int count;

    private JPanel contentPane;
    private JPasswordField passwordField;
    private final Action action = new SwingAction();
    private JTextField textField;

    /**
     * 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();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public Login() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        JLabel label = new JLabel("");
        label.setBounds(217, 5, 212, 126);
        contentPane.add(label);

        JButton btnLogin = new JButton("Login");
        btnLogin.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                for (int i = 0; i<list.size(); i++){
                    if (Arrays.equals(list.get(i).password.toCharArray(), textField.getText().toCharArray())){
                        System.out.println("found the account");
                        if (Arrays.equals(list.get(i).password.toCharArray(), passwordField.getPassword())){

                            current = list.get(i);

                            EventQueue.invokeLater(new Runnable() {
                                public void run() {
                                    try {
                                        overview frame = new overview();
                                        frame.setVisible(true);
                                    } catch (Exception e) {
                                        e.printStackTrace();
                                    }
                                }
                            });
                        }
                        else{
                            JOptionPane.showMessageDialog(null, "Password does not match our records", "Error", JOptionPane.INFORMATION_MESSAGE);
                        }
                    }
                    else{
                            JOptionPane.showMessageDialog(null, "Account number not found", "Error", JOptionPane.INFORMATION_MESSAGE);
                        }

            }
            }
        });
        btnLogin.setAction(action);
        btnLogin.setBounds(108, 186, 89, 23);
        contentPane.add(btnLogin);

        JButton btnRegister = new JButton("Register");
        btnRegister.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                EventQueue.invokeLater(new Runnable() {
                    public void run() {
                        try {
                            Register frame = new Register();
                            frame.setVisible(true);
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                });
            }
        });
        btnRegister.setBounds(217, 186, 89, 23);
        contentPane.add(btnRegister);

        passwordField = new JPasswordField();
        passwordField.setBounds(172, 148, 142, 20);
        contentPane.add(passwordField);

        JPanel panel = new JPanel();
        panel.setBackground(Color.BLUE);
        panel.setBounds(39, 32, 335, 51);
        contentPane.add(panel);

        JLabel lblLogin = new JLabel("Login");
        lblLogin.setFont(new Font("Verdana", Font.BOLD, 15));
        panel.add(lblLogin);
        lblLogin.setForeground(SystemColor.window);
        lblLogin.setBackground(Color.BLUE);

        JLabel lblAccountNumber = new JLabel("Account Number:");
        lblAccountNumber.setBounds(49, 101, 113, 14);
        contentPane.add(lblAccountNumber);

        JLabel lblPassword = new JLabel("Password:\r\n");
        lblPassword.setBounds(49, 151, 113, 14);
        contentPane.add(lblPassword);

        textField = new JTextField();
        textField.setBounds(172, 98, 142, 20);
        contentPane.add(textField);
        textField.setColumns(10);
    }
    public void printLogin(Login l) {
        System.out.println(l.firstName);
        System.out.println(l.lastName);
        System.out.println(l.account);
        System.out.println(l.birthYear);
        System.out.println(l.password);
    }
    private class SwingAction extends AbstractAction {
        public SwingAction() {
            putValue(NAME, "Login");
            putValue(SHORT_DESCRIPTION, "Login to your account");
        }
        public void actionPerformed(ActionEvent e) {
        }
    }
}

当按下“登录”按钮但当前无效时，代码应该运行程序。

Answer 1

下面有一个问题：

if (list.get(i).password.equals(passwordField.getPassword())){

JPasswordField#getPassword()返回char[]，比较字符串password和char[]错误。

尝试Arrays.equals()比较数组如下：

Arrays.equals(list.get(i).password.toCharArray(), passwordField.getPassword());

我建议您使用Map代替ArrayList。将username作为地图的关键。

使用

Map<String,Login> map = new HashMap<String,Login>();

而不是

ArrayList<Login> list= new ArrayList<Login>();

Map搜索速度比ArrayList更快。

Answer 2

我希望我的笔记能够提供帮助：

没有main方法来使类可运行
此处不允许list.add(test);的位置。它应该在构造函数/方法中。

在arraylist中搜索用户名和密码

2 个答案: