java/BankAccount/src/BankAccount.java

public class BankAccount {
    // 私有属性（封装）
    private final String accountNumber; // 账户号，创建后不可修改
    private String ownerName;           // 户主姓名，可修改
    private double balance;            // 余额，只能通过存取款修改

    // 构造方法：必须传入账户号和户主姓名，初始余额为0
    public BankAccount(String accountNumber, String ownerName) {
        this.accountNumber = accountNumber;
        this.ownerName = ownerName;
        this.balance = 0.0;
    }

    // 存款方法
    public void deposit(double amount) {
        if (amount > 0) {
            balance += amount;
            System.out.println("存款成功！当前余额：" + balance);
        } else {
            System.out.println("存款失败！金额必须大于0。");
        }
    }

    // 取款方法
    public void withdraw(double amount) {
        if (amount > 0 && amount <= balance) {
            balance -= amount;
            System.out.println("取款成功！当前余额：" + balance);
        } else {
            System.out.println("取款失败！金额必须大于0且不超过当前余额。");
        }
    }

    // 查询余额
    public double getBalance() {
        return balance;
    }

    // 户主姓名 getter/setter（允许修改）
    public String getOwnerName() {
        return ownerName;
    }

    public void setOwnerName(String ownerName) {
        this.ownerName = ownerName;
    }

    // 账户号 getter（无setter，保证不可修改）
    public String getAccountNumber() {
        return accountNumber;
    }
}