Java番外之异常处理（bank项目7）

Bank项目7

背景：Bank项目6续

---

添加自定义异常类

package banking7.domain;

public class OverdraftException extends Exception {
    static final long serialVersionUID = -112223311L;//key
    private double deficit;//表示所取的钱与余额的差额

    public double getDeficit() {
        return deficit;
    }

    public OverdraftException(String msg,double deficit) {
        super(msg);//key
        this.deficit = deficit;
    }


}

• 注意key处

---

修改Account类

withdraw方法

• 手动抛异常

Account类代码

package banking7.domain;


public class Account {
    protected double balance;

    public Account(double init_balance){
        balance = init_balance;
    }

    public double getBalance(){
        return balance;
    }

    public boolean deposit(double amt){
         balance += amt;
         return true;
    }

    public void withdraw(double amt) throws OverdraftException{//amt为要取的额度
        if(balance >= amt){
            balance -= amt;

        }else{
             throw new OverdraftException("资金不足", amt - balance);
        }
    }
}

---

修改CheckingAccount类

withdraw方法

成员变量类型（包装类）

• double–>Double
• 取值null：空，未赋值，表示无透支额度
• 取值0：有透支额度，但为0

CheckingAccount类代码

package banking7.domain;

public class CheckAccount extends Account {
    private Double overdraftProtection;

    public CheckAccount(double balance) {
        super(balance);

    }

    public CheckAccount(double balance, double protect) {
        super(balance);
        this.overdraftProtection = protect;
    }

    public double getOverdraftProtection() {
        return overdraftProtection;
    }

    public void setOverdraftProtection(double overdraftProtection) {
        this.overdraftProtection = overdraftProtection;
    }

    public void withdraw(double amt) throws OverdraftException {
        if (balance >= amt) {
            balance -= amt;
            // return true;
        } else {
            if (overdraftProtection == null) {
                throw new OverdraftException("no overdraft protection", amt
                        - balance);
            } else if (overdraftProtection <= amt - balance) {// insufficient
                throw new OverdraftException(
                        "Insufficient funs for overdraft protection", amt
                                - balance);
            } else {
                overdraftProtection -= (amt - balance);
                balance = 0;
            }
        }
    }
}

---

测试类

package TestBanking;

/*
 * This class creates the program to test the banking classes.
 * It creates a set of customers, with a few accounts each,
 * and generates a report of current account balances.
 */

import banking7.domain.Account;
import banking7.domain.Bank;
import banking7.domain.CheckAccount;
import banking7.domain.Customer;
import banking7.domain.OverdraftException;
import banking7.domain.SavingAccount;

public class TestBanking7 {

    public static void main(String[] args) {
        Bank bank = Bank.getBanking();
        Customer customer;
        Account account;

        // Create two customers and their accounts
        bank.addCustomer("Jane", "Simms");
        customer = bank.getCustomer(0);
        customer.addAccount(new SavingAccount(500.00, 0.05));
        customer.addAccount(new CheckAccount(200.00, 500.00));
        bank.addCustomer("Owen", "Bryant");
        customer = bank.getCustomer(1);
        customer.addAccount(new CheckAccount(200.00));

        // Test the checking account of Jane Simms (with overdraft protection)
        customer = bank.getCustomer(0);
        account = customer.getAccount(1);
        System.out
                .println("Customer [" + customer.getLastName() + ", "
                        + customer.getFirstName() + "]"
                        + " has a checking balance of " + account.getBalance()
                        + " with a 500.00 overdraft protection.");
        try {
            System.out.println("Checking Acct [Jane Simms] : withdraw 150.00");
            account.withdraw(150.00);
            System.out.println("Checking Acct [Jane Simms] : deposit 22.50");
            account.deposit(22.50);
            System.out.println("Checking Acct [Jane Simms] : withdraw 147.62");
            account.withdraw(147.62);
            System.out.println("Checking Acct [Jane Simms] : withdraw 470.00");
            account.withdraw(470.00);
        } catch (OverdraftException e1) {
            System.out.println("Exception: " + e1.getMessage() + "   Deficit: "
                    + e1.getDeficit());
        } finally {
            System.out.println("Customer [" + customer.getLastName() + ", "
                    + customer.getFirstName() + "]"
                    + " has a checking balance of " + account.getBalance());
        }
        System.out.println();

        // Test the checking account of Owen Bryant (without overdraft
        // protection)
        customer = bank.getCustomer(1);
        account = customer.getAccount(0);
        System.out.println("Customer [" + customer.getLastName() + ", "
                + customer.getFirstName() + "]" + " has a checking balance of "
                + account.getBalance());
        try {
            System.out.println("Checking Acct [Owen Bryant] : withdraw 100.00");
            account.withdraw(100.00);
            System.out.println("Checking Acct [Owen Bryant] : deposit 25.00");
            account.deposit(25.00);
            System.out.println("Checking Acct [Owen Bryant] : withdraw 175.00");
            account.withdraw(175.00);
        } catch (OverdraftException e1) {
            System.out.println("Exception: " + e1.getMessage() + "   Deficit: "
                    + e1.getDeficit());
        } finally {
            System.out.println("Customer [" + customer.getLastName() + ", "
                    + customer.getFirstName() + "]"
                    + " has a checking balance of " + account.getBalance());
        }
    }
}

输出结果

Customer [Simms, Jane] has a checking balance of 200.0 with a 500.00 overdraft protection.
Checking Acct [Jane Simms] : withdraw 150.00
Checking Acct [Jane Simms] : deposit 22.50
Checking Acct [Jane Simms] : withdraw 147.62
Checking Acct [Jane Simms] : withdraw 470.00
Exception: Insufficient funs for overdraft protection   Deficit: 470.0
Customer [Simms, Jane] has a checking balance of 0.0

Customer [Bryant, Owen] has a checking balance of 200.0
Checking Acct [Owen Bryant] : withdraw 100.00
Checking Acct [Owen Bryant] : deposit 25.00
Checking Acct [Owen Bryant] : withdraw 175.00
Exception: no overdraft protection   Deficit: 50.0
Customer [Bryant, Owen] has a checking balance of 125.0