java编写一个ATM 柜员机模拟程序 模拟 ATM 柜员机的相关功能，实现其存款、取款、余额查询、密码修改等相关功能， 属于验证性实验。目的是通过实验了解图形用户界面程序的开发；图形用户界面设计方法； 常用 swing 组件的使用；事件处理程序设计

好的，以下是一个简单的ATM柜员机模拟程序的Java代码：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ATM extends JFrame implements ActionListener {
    private JTextField tfDeposit;
    private JTextField tfWithdraw;
    private JLabel lblBalance;
    private JPasswordField pfOld;
    private JPasswordField pfNew;
    private JPasswordField pfConfirm;

    private double balance;
    private String password;

    public ATM() {
        super("ATM");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(400, 300);

        JLabel lblTitle = new JLabel("ATM");
        lblTitle.setFont(new Font("Arial", Font.BOLD, 24));
        add(lblTitle, BorderLayout.NORTH);

        JPanel panel = new JPanel(new GridLayout(5, 2));
        panel.add(new JLabel("Deposit:"));
        tfDeposit = new JTextField();
        panel.add(tfDeposit);
        panel.add(new JLabel("Withdraw:"));
        tfWithdraw = new JTextField();
        panel.add(tfWithdraw);
        panel.add(new JLabel("Balance:"));
        lblBalance = new JLabel("0.00");
        panel.add(lblBalance);

        JButton btnDeposit = new JButton("Deposit");
        btnDeposit.addActionListener(this);
        panel.add(btnDeposit);

        JButton btnWithdraw = new JButton("Withdraw");
        btnWithdraw.addActionListener(this);
        panel.add(btnWithdraw);

        add(panel, BorderLayout.CENTER);

        JPanel panel2 = new JPanel(new GridLayout(4, 2));
        panel2.add(new JLabel("Old password:"));
        pfOld = new JPasswordField();
        panel2.add(pfOld);
        panel2.add(new JLabel("New password:"));
        pfNew = new JPasswordField();
        panel2.add(pfNew);
        panel2.add(new JLabel("Confirm password:"));
        pfConfirm = new JPasswordField();
        panel2.add(pfConfirm);

        JButton btnChangePassword = new JButton("Change password");
        btnChangePassword.addActionListener(this);
        panel2.add(btnChangePassword);

        add(panel2, BorderLayout.SOUTH);

        balance = 1000.00;
        password = "1234";
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getActionCommand().equals("Deposit")) {
            double amount = Double.parseDouble(tfDeposit.getText());
            balance += amount;
            lblBalance.setText(String.format("%.2f", balance));
            tfDeposit.setText("");
        } else if (e.getActionCommand().equals("Withdraw")) {
            double amount = Double.parseDouble(tfWithdraw.getText());
            if (amount > balance) {
                JOptionPane.showMessageDialog(this, "Insufficient funds.");
            } else {
                balance -= amount;
                lblBalance.setText(String.format("%.2f", balance));
            }
            tfWithdraw.setText("");
        } else if (e.getActionCommand().equals("Change password")) {
            String oldPassword = new String(pfOld.getPassword());
            String newPassword = new String(pfNew.getPassword());
            String confirmPassword = new String(pfConfirm.getPassword());
            if (!oldPassword.equals(password)) {
                JOptionPane.showMessageDialog(this, "Incorrect old password.");
            } else if (!newPassword.equals(confirmPassword)) {
                JOptionPane.showMessageDialog(this, "Passwords do not match.");
            } else {
                password = newPassword;
                JOptionPane.showMessageDialog(this, "Password changed.");
                pfOld.setText("");
                pfNew.setText("");
                pfConfirm.setText("");
            }
        }
    }

    public static void main(String[] args) {
        ATM atm = new ATM();
        atm.setVisible(true);
    }
}

这个程序使用了Swing组件来创建图形用户界面。它有两个面板，一个面板用于处理存款、取款和余额查询，另一个面板用于处理密码修改。当用户输入存款或取款金额时，程序会更新余额并将其显示在标签上。当用户点击“Change password”按钮时，程序会先检查旧密码是否正确，然后检查新密码是否与确认密码匹配，最后更新密码并显示一条消息框。