求帮忙建类。。

要求如下。。老师布置的作业。。求帮忙。。
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Account//类，
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#balance:double//余额balance
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+Account(double:balance)//
+getBalance():double//获得余额
+deposit(double:amount):boolean//存钱
+withdraw(double:amount):boolean//取钱
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SavingAccount(extends Account)//普通存储账户
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-rate:double
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+SavingAccount(double:balance, double rate)
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CheckingAccount(extends Account)//信用卡账户，继承account
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-overdraft:double//透支额度
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+CheckingAccount(double:balance, double overdraft)
+CheckingAccount(double:balance)
+withdraw(double:amount):boolean
+getOverdraft():double
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Customer
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-account:Account
-name:String
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+Customer(String:name)
+getAccount():Account
+setAccount(Account:account):void
+getName():String
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Bank
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-customers:Customer[]
-custNum:int
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+Bank()
+addCustomer(Customer:customer):void
+getCustomer(int:index):Customer
+getCustomerNum():int
==============================================1. 将类结构以代码形式表示，并对方法和构造器提供合理的实现。
2. 使用TestBanking类对代码进行测试