用java定义一个银行卡类实现存款与查询余额的方法

public class BankCard {
    private String accountNumber; // 银行卡号
    private String accountName; // 银行卡户名
    private double balance; // 银行卡余额
    
    public BankCard(String accountNumber, String accountName, double balance) {
        this.accountNumber = accountNumber;
        this.accountName = accountName;
        this.balance = balance;
    }
    
    // 存款
    public void deposit(double amount) {
        balance += amount;
    }
    
    // 查询余额
    public double getBalance() {
        return balance;
    }
}

使用示例：

BankCard card = new BankCard("1234567890", "张三", 1000.0);
card.deposit(500.0); // 存入500元
double balance = card.getBalance(); // 查询余额
System.out.println("余额为：" + balance);
``