BankAccount类的成员变量： 账户名、账号、余额、账户等级 用枚举类型BankAccountGrade表示账户的等级。共有两种等级: VIP和GENERAL，给出代码示例

在Java中，我们可以创建一个名为`BankAccount`的类，包含指定的成员变量，其中账户等级使用`enum`类型来表示。以下是详细的代码示例：

public class BankAccount {
    private String accountName;
    private String accountNumber;
    private double balance;
    private BankAccountGrade accountGrade;

    // 定义账户等级枚举类型
    public enum BankAccountGrade {
        VIP, // 贵宾级别
        GENERAL // 普通级别
    }

    // 构造函数
    public BankAccount(String name, String number, double initialBalance, BankAccountGrade grade) {
        this.accountName = name;
        this.accountNumber = number;
        this.balance = initialBalance;
        this.accountGrade = grade;
    }

    // 获取和设置方法
    public String getAccountName() {
        return accountName;
    }

    public void setAccountName(String accountName) {
        this.accountName = accountName;
    }

    public String getAccountNumber() {
        return accountNumber;
    }

    public void setAccountNumber(String accountNumber) {
        this.accountNumber = accountNumber;
    }

    public double getBalance() {
        return balance;
    }

    public void deposit(double amount) {
        balance += amount;
    }

    public void withdraw(double amount) {
        if (amount <= balance) {
            balance -= amount;
        } else {
            System.out.println("Insufficient balance");
        }
    }

    public BankAccountGrade getAccountGrade() {
        return accountGrade;
    }

    public void setAccountGrade(BankAccountGrade accountGrade) {
        this.accountGrade = accountGrade;
    }

    // 示例：VIP账户额外功能
    public boolean isPremiumFeatureAvailable() {
        return accountGrade == BankAccountGrade.VIP;
    }

    // 用于演示目的 - 打印账户信息
    @Override
    public String toString() {
        return "Account Name: " + accountName + ", Account Number: " + accountNumber +
               ", Balance: " + balance + ", Grade: " + accountGrade;
    }
}

// 使用示例
BankAccount generalAccount = new BankAccount("John Doe", "123456", 1000, BankAccountGrade.GENERAL);
System.out.println(generalAccount); // 输出普通账户的信息

BankAccount vipAccount = new BankAccount("Jane Smith", "789012", 5000, BankAccountGrade.VIP);
System.out.println(vipAccount); // 输出贵宾账户的信息

在这个例子中，`BankAccount`类包含了账户的基本属性和操作，如名称、号码、余额以及账户等级。VIP账户通过`isPremiumFeatureAvailable()`方法提供了额外的功能。