1 实验题目 5：
 2  在银行项目中创建 Account 的两个子类：SavingAccount 和 CheckingAccount
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 5 实验目的：
 6  继承、多态、方法的重写。
 7  提 示：
 8  创建 Account 类的两个子类：SavingAccount 和 CheckingAccount 子类
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10 a. 修改 Account 类；将 balance 属性的访问方式改为 protected
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12 b. 创建 SavingAccount 类，该类继承 Account 类
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14 c. 该类必须包含一个类型为 double 的 interestRate 属性
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16 d. 该类必须包括带有两个参数（balance 和 interest_rate）的公有构造器。该 构 造器必须通过调用 super(balance)将 balance 参数传递给父类构造 器。
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18 实现 CheckingAccount 类
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20 1． CheckingAccount 类必须扩展 Account 类
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22 2． 该类必须包含一个类型为 double 的 overdraftProtection 属性。
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24 3． 该类必须包含一个带有参数（balance）的共有构造器。该构造器必须通过调 用 super(balance)将 balance 参数传递给父类构造器。
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26 4． 给类必须包括另一个带有两个参数（balance 和 protect）的公有构造器。该 构造器必须通过调用 super(balance)并设置 overdragtProtection 属性， 将 balance 参数传递给父类构造器。
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28 5． CheckingAccount 类必须覆盖 withdraw 方法。此方法必须执行下列检 查。如 果当前余额足够弥补取款 amount,则正常进行。如果不够弥补但是 存在透支 保护，则尝试用 overdraftProtection 得值来弥补该差值 （balance-amount）. 如果弥补该透支所需要的金额大于当前的保护级别。 则整个交易失败，但余 额未受影响。 

package Banking_5;
public class Account {protected double balance;//余额  ,uml前该变量是 '-'public Account(double init_balance){balance=init_balance;}public double getBalance() {return balance;}public void setBalance(double b){this.balance=b;}//存钱public boolean deposit(double amt){this.balance+=amt;return true;}//取钱public Boolean withdraw(double amt) {if(amt>this.balance)return false;else{this.balance-=amt;return true;}}
}

package Banking_5;public class Bank {private Customer[] customers ;   //用于存放客户private int numberofCustomers; //用于记录Customer的个数public Bank(){numberofCustomers=0;customers = new Customer[100];  ///这里记得要初始化!不然要发生java.lang.NullPointerException
    }public void addCustomer(String f,String l){int i= this.numberofCustomers;customers[i]=new Customer(f,l);//新建一个构造对象this.numberofCustomers++;}public int getNumOfCustomers() {return numberofCustomers;}public Customer getCustomer(int index) {return customers[index];}
}

package Banking_5;public class CheckingAccount extends Account{private double overdraft;//超额限额保护public CheckingAccount(double balance,double overd){super(balance);this.overdraft=overd;}public void showinfo(){System.out.println("您的余额:"+this.getBalance()+"\t"+"您的可透支余额:"+this.overdraft);}public Boolean withdraw(double amt){if(amt<=super.getBalance())super.setBalance(super.getBalance()-amt );else{double val=amt-super.getBalance();if(val<=this.overdraft){super.setBalance(0);this.overdraft-=val;}else{System.out.println("该消费超过可透支额的限额");return false;}}return true;}
}

package Banking_5;public class Customer {private String firstName;private String lastName;private  Account account;public Customer(){}public Customer(String f, String l){this.firstName=f;this.lastName=l;}public String getFirstName() {return firstName;}public String getLastName() {return lastName;}public Account getAccount() {return account;}public void setAccount(Account account) {this.account = account;}
}

package Banking_5;
public class SavingAccount extends Account{private double interest_Rate;  //利率public SavingAccount(double balance,double interest_Rate){super(balance);this.interest_Rate=interest_Rate;}
}

package TestBanks;
import Banking_5.*;public class TestBanking_5 {public static void main(String[] args) {Bank     bank = new Bank();Customer customer;Account account;//// Create Bank customers and their accountSystem.out.println("Creating the customer Jane Smith.");System.out.println("Creating her Savings Account with a 500.00 balance and 3% interest.");bank.addCustomer("Jane", "Simms");customer = bank.getCustomer(0);account = new SavingAccount(500,0.03);customer.setAccount(account);System.out.println("Creating the customer Owen Bryant.");//codebank.addCustomer("Owen","Bryant");customer=bank.getCustomer(1);account=new CheckingAccount(500,0);customer.setAccount(account);System.out.println("Creating his Checking Account with a 500.00 balance and no overdraft protection.");//codeSystem.out.println("Creating the customer Tim Soley.");bank.addCustomer("Tim", "Soley");customer = bank.getCustomer(2);account=new CheckingAccount(500,500);customer.setAccount(account);System.out.println("Creating his Checking Account with a 500.00 balance and 500.00 in overdraft protection.");//code
System.out.println("Creating the customer Maria Soley.");bank.addCustomer("Maria", "Soley");customer = bank.getCustomer(3);System.out.println("Maria shares her Checking Account with her husband Tim.");customer.setAccount(bank.getCustomer(2).getAccount());System.out.println();//// Demonstrate behavior of various account types//// Test a standard Savings AccountSystem.out.println("Retrieving the customer Jane Smith with her savings account.");customer = bank.getCustomer(0);account = customer.getAccount();// Perform some account transactionsSystem.out.println("Withdraw 150.00: " + account.withdraw(150.00));System.out.println("Deposit 22.50: " + account.deposit(22.50));System.out.println("Withdraw 47.62: " + account.withdraw(47.62));System.out.println("Withdraw 400.00: " + account.withdraw(400.00));// Print out the final account balanceSystem.out.println("Customer [" + customer.getLastName()+ ", " + customer.getFirstName()+ "] has a balance of " + account.getBalance());System.out.println();// Test a Checking Account w/o overdraft protectionSystem.out.println("Retrieving the customer Owen Bryant with his checking account with no overdraft protection.");customer = bank.getCustomer(1);account = customer.getAccount();// Perform some account transactionsSystem.out.println("Withdraw 150.00: " + account.withdraw(150.00));System.out.println("Deposit 22.50: " + account.deposit(22.50));System.out.println("Withdraw 47.62: " + account.withdraw(47.62));System.out.println("Withdraw 400.00: " + account.withdraw(400.00));// Print out the final account balanceSystem.out.println("Customer [" + customer.getLastName()+ ", " + customer.getFirstName()+ "] has a balance of " + account.getBalance());System.out.println();// Test a Checking Account with overdraft protectionSystem.out.println("Retrieving the customer Tim Soley with his checking account that has overdraft protection.");customer = bank.getCustomer(2);account = customer.getAccount();// Perform some account transactionsSystem.out.println("Withdraw 150.00: " + account.withdraw(150.00));System.out.println("Deposit 22.50: " + account.deposit(22.50));System.out.println("Withdraw 47.62: " + account.withdraw(47.62));System.out.println("Withdraw 400.00: " + account.withdraw(400.00));// Print out the final account balanceSystem.out.println("Customer [" + customer.getLastName()+ ", " + customer.getFirstName()+ "] has a balance of " + account.getBalance());System.out.println();// Test a Checking Account with overdraft protectionSystem.out.println("Retrieving the customer Maria Soley with her joint checking account with husband Tim.");customer = bank.getCustomer(3);account = customer.getAccount();// Perform some account transactionsSystem.out.println("Deposit 150.00: " + account.deposit(150.00));System.out.println("Withdraw 750.00: " + account.withdraw(750.00));// Print out the final account balanceSystem.out.println("Customer [" + customer.getLastName()+ ", " + customer.getFirstName()+ "] has a balance of " + account.getBalance());}
}

Creating the customer Jane Smith.
Creating her Savings Account with a 500.00 balance and 3% interest.
Creating the customer Owen Bryant.
Creating his Checking Account with a 500.00 balance and no overdraft protection.
Creating the customer Tim Soley.
Creating his Checking Account with a 500.00 balance and 500.00 in overdraft protection.
Creating the customer Maria Soley.
Maria shares her Checking Account with her husband Tim.Retrieving the customer Jane Smith with her savings account.
Withdraw 150.00: true
Deposit 22.50: true
Withdraw 47.62: true
Withdraw 400.00: false
Customer [Simms, Jane] has a balance of 324.88Retrieving the customer Owen Bryant with his checking account with no overdraft protection.
Withdraw 150.00: true
Deposit 22.50: true
Withdraw 47.62: true
该消费超过可透支额的限额
Withdraw 400.00: false
Customer [Bryant, Owen] has a balance of 324.88Retrieving the customer Tim Soley with his checking account that has overdraft protection.
Withdraw 150.00: true
Deposit 22.50: true
Withdraw 47.62: true
Withdraw 400.00: true
Customer [Soley, Tim] has a balance of 0.0Retrieving the customer Maria Soley with her joint checking account with husband Tim.
Deposit 150.00: true
该消费超过可透支额的限额
Withdraw 750.00: false
Customer [Soley, Maria] has a balance of 150.0