289、Java中级06 - 异常处理【异常练习**】 2019.12.03

1、练习：异常综合1

这是一个类图
Account类： 银行账号
属性： balance 余额
方法： getBalance() 获取余额
方法： deposit() 存钱
方法： withdraw() 取钱
OverdraftException： 透支异常，继承Exception
属性： deficit 透支额

public class Account {
 
    protected double balance; // 余额
 
    public Account(double balance) {
        this.balance = balance;
    }
 
    public double getBalance() {
        return balance;
    }
 
    // 存钱
    public double deposit(double amt) {
        return balance += amt;
    }
 
    // 取钱
    public double withdraw(double amt) throws OverDraftException {
        if (balance < amt) { // 若取钱金额超过余额,则会抛出异常,并根据自定义异常返回透支额
            throw new OverDraftException("您的余额为不足,您当前透支额为: " + (amt - balance), amt - balance);
        }
        return balance -= amt;
    }
 
    public static void main(String[] args) {
 
        Account money = new Account(5000);
        System.out.println("您的账户当前余额为:" + money.getBalance());
 
        money.deposit(3000);
 
        System.out.println("您的账户当前余额为:" + money.getBalance());
 
        try {
            money.withdraw(10000);
        } catch (OverDraftException e) {
            System.err.println("您的账户透支金额为:" + e.getDeficit());
            e.printStackTrace();
        }
    }
}
 
//自定义异常
public class OverDraftException extends Exception{
 
    private double deficit; // 透支额
     
    public OverDraftException(String message,double deficit) {
        super(message);
        this.deficit = deficit;
    }
     
    public double getDeficit() {
        return deficit;
    }
}

2、练习：异常综合2

类： CheckingAccount 支票账户，具备透支额度，继承Account
属性：overdraftProtection 透支额度

public class CheckingAccount extends Account {
 
    private double overDraftProtection; // 透支额度
 
    public CheckingAccount(double balance) {
        super(balance); // 显式调用父类带参构造方法
    }
 
    public CheckingAccount(double balance, double overDraftProtection) {
        super(balance); // 显式调用父类带参构造方法
        this.overDraftProtection = overDraftProtection; // 将局部变量传入成员变量中
    }
 
    public double withdraw(double amt) throws OverDraftException {
        if (balance + overDraftProtection < amt) { // 若取钱金额超过余额+透支额,则会抛出异常,并根据自定义异常返回透支额
            throw new OverDraftException("您的余额为不足,您当前透支额为: " + (amt - balance - overDraftProtection),
                    amt - balance - overDraftProtection);
        }
        return balance -= amt;
    }
 
    public static void main(String[] args) {
 
        // 拥有5000余额和250透支额度
        CheckingAccount money = new CheckingAccount(5000, 2500);
        // 存钱
        money.deposit(3000);
        // 显示余额
        System.out.println("您的账户当前余额为:" + money.getBalance());
        // 取钱
        try {
            for (int i = 0; i < Integer.MAX_VALUE; i++) {
                money.withdraw(550);
                System.out.println("取出550元,您的账户当前余额为: " + money.getBalance());
            }
        } catch (OverDraftException e) {
            System.err.println("您的账户透支金额为:" + e.getDeficit());
            e.printStackTrace();
        }
    }
}

3、参考链接

[01] How2j - 异常处理系列教材 （六）- JAVA 异常综合练习题