深入IComparable与IComparer的排序实例详解

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;
namespace hgoApp
{
    class Comparer
    {
        static void Main()
        {
            Employee[] Employees = new Employee[5];

            Employees[0] = new Employee("张三", 2800);
            Employees[1] = new Employee("李四", 1800);
            Employees[2] = new Employee("王五", 5800);
            Employees[3] = new Employee("马六", 12800);
            Employees[4] = new Employee("钱七", 8800);
            Console.WriteLine("按照姓名排序");
            Array.Sort(Employees);
            foreach (Employee em in Employees)
            {
                Console.WriteLine(em);
            }
            Console.WriteLine("按照薪水排序");
            Array.Sort(Employees, Employee.SalaryCom);
            foreach (Employee em in Employees)
            {
                Console.WriteLine(em);
            }
        }
    }
    class Employee : IComparable
    {
        private string _Name;
        public string Name
        {
            get { return _Name; }
        }
        private int _Salary;
        public int Salary
        {
            get { return _Salary; }
        }
        public Employee(string Name, int Salary)
        {
            _Name = Name;
            _Salary = Salary;
        }
        //显示接口实现
        int IComparable.CompareTo(object obj)
        {
            if (!(obj is Employee))
            {
                throw new ArgumentException("不是Employee类");
            }
            return _Name.CompareTo(((Employee)obj)._Name);
        }
        //提供一个公用的强类型重载版本
        public int CompareTo(Employee Em)
        {
            return _Name.CompareTo(Em._Name);
        }
        //当第一次实例化Employee的时候,_SalaryCom为空,当使用SalaryCom时,就会创建一个SalaryCompare对象,第2次，3次的时候,就可以直接使用_SalaryCom了
        private static SalaryCompare _SalaryCom = null;
        public static IComparer SalaryCom
        {
            get
            {
                if (_SalaryCom == null)
                {
                    _SalaryCom = new SalaryCompare();
                }
                return _SalaryCom;
            }
        }
        //嵌套类(这个类是针对薪水进行排序的类)
        private class SalaryCompare:IComparer
        {
            //使用指定的IComparer对Array中的元素进行排序
            int IComparer.Compare(object obj1,object obj2)
            {
                if (!(obj1 is Employee) || !(obj2 is Employee))
                {
                    throw new ArgumentException("不是Employee类");
                }
                return ((Employee)obj1)._Salary.CompareTo(((Employee)obj2)._Salary);
            }
        }
        public override string ToString()
        {
            return _Name +"  "+ _Salary.ToString();
        }
    }
}