C#_IComparer实例 - 实现ID或者yearOfscv排序

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ComparerTest
{
class Employee : IComparable<Employee>
{
private int empID;
private int yearOfSvc = 1;

public Employee(int empID)
{
this.empID = empID;
}

public Employee(int empID, int yearOfSvc)
{
this.empID = empID;
this.yearOfSvc = yearOfSvc;
}

public override string ToString()
{
return "ID: " + empID.ToString()
+ "  yearOfSvc: " + yearOfSvc.ToString();
}

public bool Equals(Employee other)
{
if (this.empID == other.empID)
{
return true;
}
else
{
return false;
}
}

//获取Comparer对象的静态方法
public static EmployeeComparer GetComparer()
{
return new Employee.EmployeeComparer();
}
//比较委托回Employee
//Employee使用整形的默认
//CompareTo方法
public int CompareTo(Employee rhs)
{
return this.empID.CompareTo(rhs.empID);
}

//自定义Comparer要调用的特殊表现
public int CompareTo(Employee rhs,
Employee.EmployeeComparer.ComparisonType whichComparision)
{
switch (whichComparision)
{
case Employee.EmployeeComparer.ComparisonType.EmpID:
return this.empID.CompareTo(rhs.empID);
case Employee.EmployeeComparer.ComparisonType.Yrs:
return this.yearOfSvc.CompareTo(rhs.yearOfSvc);
}
return 0;
}

//实现IComparer的内嵌类
public class EmployeeComparer : IComparer<Employee>
{
private Employee.EmployeeComparer.ComparisonType whichComparision;

public enum ComparisonType
{
EmpID,
Yrs
};

public bool Equals(Employee lhs, Employee rhs)
{
return this.Compare(lhs, rhs) == 0;
}
//让Empolyee对象自己比较
public int Compare(Employee lhs, Employee rhs)
{
return lhs.CompareTo(rhs, WhichComparison);
}

public int GetHashCode(Employee e)
{
return e.GetHashCode();
}

public Employee.EmployeeComparer.ComparisonType WhichComparison
{
set
{
whichComparision = value;
}
get
{
return whichComparision;
}

}
}
}
class Program
{
static void Main(string[] args)
{
List<Employee> empArray = new List<Employee>();

Random ra = new Random();

for (int i = 0; i < 5; i++)
{
empArray.Add(new Employee(ra.Next(10)+100,ra.Next(20)));
}

for (int i = 0; i < empArray.Count; i++)
{
Console.Write("\n{0}",empArray[i].ToString());
}
Console.WriteLine();
Console.WriteLine();
Employee.EmployeeComparer c =  Employee.GetComparer();

c.WhichComparison = Employee.EmployeeComparer.ComparisonType.EmpID;

empArray.Sort(c);

for (int i = 0; i < empArray.Count; i++)
{
Console.Write("\n{0}", empArray[i].ToString());
}
Console.WriteLine();
Console.WriteLine();
Employee.EmployeeComparer c2 = Employee.GetComparer();

c.WhichComparison = Employee.EmployeeComparer.ComparisonType.Yrs;

empArray.Sort(c2);

for (int i = 0; i < empArray.Count; i++)
{
Console.Write("\n{0}", empArray[i].ToString());
}
Console.ReadLine();
}
}
}