Java CheckingAccount 类中如何防止超出透支限额？

Question

当我尝试提取超过透支限额的金额时，就会出现问题。在这个例子中，第二次提款后的余额不应低于允许的透支限额，但事实却是这样。

如何修改

CheckingAccount

类中的提现方法，防止提现超出透支限额？

interface Account {
    void deposit(double amount);
    void withdraw(double amount);
    double getBalance();
}

abstract class BankAccount implements Account {
    protected double balance;
    protected String accountNumber;

    public BankAccount(String accountNumber, double initialBalance) {
        this.accountNumber = accountNumber;
        this.balance = initialBalance;
    }

    @Override
    public double getBalance() {
        return balance;
    }
}

class SavingsAccount extends BankAccount {
    private double interestRate;

    public SavingsAccount(String accountNumber, double initialBalance, double interestRate) {
        super(accountNumber, initialBalance);
        this.interestRate = interestRate;
    }

    public void addInterest() {
        balance += balance * interestRate;
    }

    @Override
    public void deposit(double amount) {
        if (amount > 0) {
            balance += amount;
        }
    }

    @Override
    public void withdraw(double amount) {
        if (amount > 0 && amount <= balance) {
            balance -= amount;
        }
    }
}

class CheckingAccount extends BankAccount {
    private double overdraftLimit;

    public CheckingAccount(String accountNumber, double initialBalance, double overdraftLimit) {
        super(accountNumber, initialBalance);
        this.overdraftLimit = overdraftLimit;
    }

    @Override
    public void deposit(double amount) {
        if (amount > 0) {
            balance += amount;
        }
    }

    @Override
    public void withdraw(double amount) {
        if (amount > 0 && amount <= balance + overdraftLimit) {
            balance -= amount;
        }
    }
}

public class Bank {
    public static void main(String[] args) {
        SavingsAccount savings = new SavingsAccount("SA123", 1000, 0.05);
        CheckingAccount checking = new CheckingAccount("CA123", 500, 200);

        savings.deposit(200);
        savings.addInterest();
        System.out.println("Savings Account Balance: " + savings.getBalance());

        checking.withdraw(600);
        System.out.println("Checking Account Balance: " + checking.getBalance());

        // Attempt to withdraw more than allowed overdraft limit
        checking.withdraw(200);
        System.out.println("Checking Account Balance after overdraft: " + checking.getBalance());
    }
}

Answer 1

您可以尝试这个解决方案：

public void withdraw(double amount) {
    if (amount > 0 && amount <= balance + overdraftLimit) {
        if (amount <= balance) {
            balance -= amount;
        } else {
            // Calculate how much can be withdrawn within the overdraft limit
            double availableBalance = balance + overdraftLimit;
            balance = 0; // Account balance becomes zero after using overdraft
            System.out.println("Withdrawal exceeds balance. Using overdraft.");
            System.out.println("Overdraft used: " + (amount - balance));
        }
    } else {
        System.out.println("Withdrawal amount exceeds available balance and overdraft limit.");
    }
}