银行类题目

练习1：创建一个简单的银行程序包

练习目标－Java 语言中面向对象的封装性及构造器的使用。

任务

在这个练习里，创建一个简单版本的（账户类）Account类。将这个源文件放入banking程序包中。在创建单个帐户的默认程序包中，已编写了一个测试程序TestBanking。这个测试程序初始化帐户余额，并可执行几种简单的事物处理。最后，该测试程序显示该帐户的最终余额。

1．  创建banking 包

2．  在banking 包下创建Account类。该类必须实现上述UML框图中的模型。

1. 声明一个私有对象属性：balance，这个属性保留了银行帐户的当前（或即时）余额。
2. 声明一个带有一个参数（init_balance）的公有构造器，这个参数为balance属性赋值。
3. 声明一个公有方法getBalance，该方法用于获取经常余额。
4. 声明一个公有方法deposit,该方法向当前余额增加金额。
5. 声明一个公有方法withdraw从当前余额中减去金额。

3．  编译TestBanking.java文件。

4．  运行TestBanking类。可以看到下列输出结果：

Creating an account with a 500.00 balance

Withdraw 150.00

Deposit 22.50

Withdraw 47.62

The account has a balance of 324.88

package banking;

public class Account {

    private double balance;

    public Account(double balance)
    {
        this.balance=balance;
    }

    public double getBalance() {
        System.out.println("当前余额为："+balance+"元");
        return balance;
    }

    public double deposit(double add){                                                                    //取钱方法
        balance+=add;
        System.out.println("存钱"+add+"元，当余额为"+balance+"元");
        return balance;
    }

    boolean    withdraw(double get){                                                                        //取钱方法
        if(get<=balance)
        {
            System.out.println("取钱"+get+"元，当余额为"+balance+"元");
            return true;
        }
        else
        {
            System.out.println("‘余额不足");
            return false;
        }        

    }

}

package banking;

public class Customer {

        private String firstName;
        private String lastName;
        private Account account;

        public Customer(String firstName,String lastName)                                //账户名字构造方法
        {
            this.firstName=firstName;
            this.lastName=lastName;
            System.out.println("用户名为："+firstName+"\t"+lastName);
        }
        public String getFirstName()
        {
            return firstName;
        }
        public String getLastName()
        {
            return lastName;
        }

        public void setAccount(Account account) {
            this.account = account;
        }

        public Account getAccount() {
            return account;
        }
        @Override
        public String toString() {
            return "Customer [account=" + account + "]";
        }

}

package banking;

public class Bank {

    private Customer customers[];
    private int numberOfCustomers[];

    //公有构造器
    public Bank() {
        customers = new Customer[5];
        numberOfCustomers = new int[5];
    }

    public static int index = 0;
    public static int c= 0;

    public void addCustome(String firstName,String lastName)
    {
        index=+c;
        customers[index] = new Customer(firstName, lastName);
        numberOfCustomers[index]=++c;
    }
    public int getNumOfCustomers()
    {
        return numberOfCustomers.length;
    }

    public Customer getCustomer(int index)
    {
        return customers[index];
    }

}

package banking;

public class SavingAccount extends Account {                //存款账户

    private double interestRate;

    public double getInterestRate() {
        return interestRate;
    }

    public void setInterestRate(double interestRate) {
        this.interestRate = interestRate;
    }

    public SavingAccount(double balance,double interestRate)
    {
        super(balance);
        this.interestRate=interestRate;
    }

}

package banking;

public class CheckingAccount extends Account{                                                    //透支账户

    private double overdraftProtection;                                                                    //属性

    public double getOverdraftProtection() {
        return overdraftProtection;
    }

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

    public CheckingAccount(double balance) {                                                        //构造方法

        super(balance);
    }

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

    boolean    withdraw(double get){                                                                        //覆盖取钱方法
        if(balance-get>0)
        {
            balance = balance - get;
            System.out.println("取钱"+get+"元，当余额为"+balance+"元");
            return true;
        }
        else
        {
            if(get<=getOverdraftProtection())
            System.out.println("‘余额为："+(balance-get));
            else
             System.out.println("请在可透支范围内提款！");
            return true;
        }        

}}