java/w3/BankAccount.java

package java01;

public class BankAccount {
    // 1. 私有成员变量（封装核心）
    private String accountNumber;  // 账号（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）

    // 2. 构造方法：创建账户时必须传入账号和户主姓名，余额初始为0
    public BankAccount(String accountNumber, String ownerName) {
        this.accountNumber = accountNumber;
        this.ownerName = ownerName;
        this.balance = 0.0;
    }

    // 3. Getter方法（对外提供查询）
    // 账号只有getter，没有setter，保证不可修改
    public String getAccountNumber() {
        return accountNumber;
    }

    public String getOwnerName() {
        return ownerName;
    }

    public double getBalance() {
        return balance;
    }

    // 4. Setter方法：只有户主姓名可以修改
    public void setOwnerName(String ownerName) {
        this.ownerName = ownerName;
    }

    // 5. 存款方法 deposit
    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！存款金额必须大于0。");
        }
    }

    // 6. 取款方法 withdraw
    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 if (amount <= 0) {
            System.out.println("取款失败！取款金额必须大于0。");
        } else {
            System.out.println("取款失败！余额不足。");
        }
    }

    // 测试主方法（可选，用来验证功能）
    public static void main(String[] args) {
        // 创建一个账户
        BankAccount account = new BankAccount("622202123456789", "张三");
        
        // 测试查询
        System.out.println("账号：" + account.getAccountNumber());
        System.out.println("户主：" + account.getOwnerName());
        System.out.println("初始余额：" + account.getBalance());
        
        // 测试存款
        account.deposit(500);
        account.deposit(-100); // 测试错误存款
        
        // 测试取款
        account.withdraw(200);
        account.withdraw(400); // 测试余额不足
        account.withdraw(-50); // 测试错误取款
    }
}