作业2：使用委托实现信用卡用户定时还款功能

一、问题分析：

　　由于信用卡本身无法还款，需要从储蓄卡中划账还款，所以应该在储蓄卡和信用卡之间建立一个委托，每到还款日自动从储蓄卡划出资金还信用卡。

二、代码展示：

namespace card_work
{
class depositCard
{
//储蓄名
private string name;
//储蓄金额
private int depositMoney;
//基础储蓄金额
public depositCard(string name, int money)
{
this.name = name;
this.depositMoney = money;
}
//获取储蓄金额
public int getDepositMoney()
{
return this.depositMoney;
}
public void setDepositMoney(int r)
{
this.depositMoney = r;
}
}
//信用卡类
class creditCard
{
//信用卡持有者名称
public string name;
//信用卡余额
public int creditMoney;
//扣款日期
public int dueDay;
//绑定储蓄卡对象
public depositCard DC;
//初始化
public creditCard(string name, int CM, int DD, depositCard DC)
{
this.name = name;
this.creditMoney = CM;
this.dueDay = DD;
this.DC = DC;
}
//还款
public void repayM()
{
Console.WriteLine("用户{0}当前金额{1}", this.name, this.DC.getDepositMoney());
DC.setDepositMoney(this.DC.getDepositMoney() + creditMoney);
Console.WriteLine("用户已还款");
Console.WriteLine("还款金额:{0}", Math.Abs(this.creditMoney));
Console.WriteLine("余下金额为{0}", DC.getDepositMoney());
Console.WriteLine();
}
//无需还款
public void norepayM()
{
Console.WriteLine("用户{0}当前金额{1}", this.name,this.DC.getDepositMoney());
Console.WriteLine("用户未到还款日期，无需还款", this.name);
Console.WriteLine();
}
}
//扣款委托类
class repayDelegate
{
//扣款委托
public delegate void repayMoney();
//扣款事件
public event repayMoney DoRepay;
//事件执行
public void NotifyRepay()
{
if (DoRepay != null)
{
Console.WriteLine("触发事件：");
DoRepay();
}
}
}
class Program
{
static void Main(string[] args)
{
depositCard D1 = new depositCard("张三", 20000);
depositCard D2 = new depositCard("李四", 20000);
depositCard D3 = new depositCard("王五", 20000);
creditCard C1 = new creditCard("张三", -9000, 5, D1);
creditCard C2 = new creditCard("李四", -6000, 31, D2);
creditCard C3 = new creditCard("王五", -1000, 5, D3);
List<creditCard> cCards = new List<creditCard>();
cCards.Add(C1);
cCards.Add(C2);
cCards.Add(C3);
//创建委托对象
repayDelegate rD = new repayDelegate();

foreach (creditCard C in cCards)
{
//判断是否到了该还款的日期
if (C.dueDay == int.Parse(DateTime.Now.ToString("yyyy-MM-dd").Split('-')[2]))
{
//事件添加
rD.DoRepay += new repayDelegate.repayMoney(C.repayM);
}
else
{
rD.DoRepay += new repayDelegate.repayMoney(C.norepayM);
}
}
//事件执行
rD.NotifyRepay();
}
}
}

三、学习心得

首先建立信用卡类和储蓄卡类，再另外建立一个委托将二者相连，设定好具体条件触发委托。