java/w3/BankAccount.java

public class BankAccount {
    private final String accountNumber; 
    private String ownerName;            
    private double balance;             
    public BankAccount(String accountNumber, String ownerName) {
        this.accountNumber = accountNumber;
        this.ownerName = ownerName;
        this.balance = 0.0; 
    }
    public String getAccountNumber() {
        return accountNumber;
    }
    public String getOwnerName() {
        return ownerName;
    }

    public void setOwnerName(String ownerName) {
        this.ownerName = ownerName;
    }
    public double getBalance() {
        return balance;
    }
    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！");
        }
    }
    public void withdraw(double amount) {
        if (amount <= 0) {
            System.out.println("取款失败：取款金额必须大于0！");
        } else if (amount > balance) {
            System.out.println("取款失败：余额不足！");
        } else {
            balance -= amount;
            System.out.println("取款成功！当前余额：" + balance);
        }
    }
    public static void main(String[] args) {
        BankAccount account = new BankAccount("622202123456789", "张三");
        System.out.println("账号：" + account.getAccountNumber());
        System.out.println("户主：" + account.getOwnerName());
        System.out.println("初始余额：" + account.getBalance());

        account.deposit(500);    
        account.withdraw(200);   
        account.withdraw(400);   
    }
}