實驗基本要求:

實驗題目 7：（在6基礎上修改） 
 將建立一個 OverdraftException 異常，它由 Account 類的withdraw()方法 拋出。 

實驗目的： 自定義異常 
 
實驗說明： 
 創建 OverdraftException 類 
 1． 在 banking.domain 包中建立一個共有類 OverdraftException. 這個類 擴展 Exception 類。  2． 添加一個 double 類型的私有屬性 deficit.增加一個共有訪問方法 getDeficit 
 3． 添加一個有兩個參數的共有構造器。deficit 參數初始化 deficit 屬性 
 
修改 Account 類 
 
4． 重寫 withdraw 方法使它不返回值（即 void）.聲明方法拋出 overdraftException異常  
5． 修改代碼拋出新異常，指明“資金不足”以及不足數額（當前余額扣除請求的數額） 
 
修改 CheckingAccount 類 

 6． 重寫 withdraw 方法使它不返回值（即 void）.聲明方法拋出 overdraftException 異常  

7． 修改代碼使其在需要時拋出異常。兩種情況要處理：第一是存在沒有透支保 護的赤字，對這個異常使用“no overdraft protection”信息。第二是 overdraftProtection 數 額 不 足 以 彌 補 赤 字 ： 對 這 個 異 常 可 使 用 ”Insufficient funds for overdraft protection” 信息 
 

工程組織:(未展示的文件和實驗6的基本完全一直)

CheckingAccount.java (錢款+額度不足, 不再返回int)

package Banking_7;


public class CheckingAccount extends Account {
    private double overdraft;//超額限額保護
    public CheckingAccount(double balance,double overd){
        super(balance);
        this.overdraft=overd;
    }
    
 
public CheckingAccount(double balance){
        super(balance);
        this.overdraft=0;
    }
    public void showinfo(){
        System.out.println("您的余額:"+this.getBalance()+"\t"+
                "您的可透支余額:"+this.overdraft);
    }
    public void withdraw(double amt) throws OverdraftException{
        
 
if(amt<=super.getBalance())
            super.setBalance(super.getBalance()-amt );
        else{
            if(this.overdraft==0){
                throw new OverdraftException("no overdraft protection(沒有透支保護):",(amt-this.balance));
            }

            double val=amt-super.getBalance();
            if(val<=this.overdraft)
            {
                super.setBalance(0);
                this.overdraft-=val;
            }
            else{
                throw new OverdraftException("Insufficient funds for overdraft protection: 數額不足以彌補赤字," +
                        "缺少資金或額度:",val-this.overdraft);
            }
        }
    }
}

Account.java

package Banking_7;
public class Account {

    protected double balance=0;//余額  ,uml前該變量是 ‘-‘
    public Account(double init_balance){
        balance=init_balance;
    }
    public double getBalance() {
        return balance;
    }
    public void setBalance(double b){this.balance=b;}
    //存錢

    public boolean deposit(double amt){
        this.balance+=amt;return true;
    }
    //取錢
    public void withdraw(double amt) throws OverdraftException{
        if(amt>this.balance){
            throw new OverdraftException("資金不足,缺少金額:",(amt-this.balance));
        }
        else{
            this.balance-=amt;
        }
    }
}

OverdraftException.java (透支額度的 異常保護機制 )

package Banking_7;

public class OverdraftException extends Exception{
    private double deficit;

    public double getDeficit() {
        return deficit;
    }

    public void setDeficit(double deficit) {
        this.deficit = deficit;
    }

    public OverdraftException(double deficit) {
        this.deficit = deficit;
    }

    public OverdraftException(String message,double deficit) {
        super(message);
        this.deficit=deficit;
        System.out.println(message+deficit);
    }

}

TestBanking_7.java (測試類)

package TestBanks;/*
 * 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 Banking_7.*;

public class TestBanking_7 {

  public static void main(String[] args) {
    Bank     bank = Bank.getBank();
    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),1);
    customer.addAccount(new CheckingAccount(200.00, 500.00),2);
    bank.addCustomer("Owen", "Bryant");
    customer = bank.getCustomer(1);
    customer.addAccount(new CheckingAccount(200.00),2);

    // Test the checking account of Jane Simms (with overdraft protection)
    customer = bank.getCustomer(0);
    account = customer.getCheckingAccount();
    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.getCheckingAccount();
    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());
    }
  }
}

運行結果:

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
Insufficient funds for overdraft protection: 數額不足以彌補赤字,缺少資金或額度:45.120000000000005
Exception: Insufficient funds for overdraft protection: 數額不足以彌補赤字,缺少資金或額度:   Deficit: 45.120000000000005
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
no overdraft protection(沒有透支保護):50.0
Exception: no overdraft protection(沒有透支保護):   Deficit: 50.0
Customer [Bryant, Owen] has a checking balance of 125.0

【Java基礎-實驗7】Banking_7 -添加銀行透支扣款系統的 thorw異常機制