利用ArrayList类编写客户信息管理程序，利用Comparer接口实现自定义Sort(IComparer comparer)排序

1.利用数组列表的常用成员，实现客户信息类内部的人员信息添加，删除，显示等功能

2.通过将客户信息类（CustomerInfo）继承实现接口IComparable成员，实现客户信息类的对象Sort()功能

3.通过自定义类实现IComparer接口成员，实现按照特定信息对客户信息的对象集合进行排序

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

namespace MyCompareInterfaceDemo
{
    /// <summary>
    /// //定义一个客户信息类
    /// </summary>
    public class CustomerInfo:IComparable
    {
        public string Name { get; set; }
        public int ID { get; set; }
        public string CompanyName { get; set; }
        public CustomerInfo(string name,int ID,string name_company)
        {
            Name = name;
            this.ID = ID;
            CompanyName = name_company;
        }
        public CustomerInfo() { }
        /// <summary>
        /// //定义一个私有的客户信息列表
        /// </summary>
        static ArrayList customers = new ArrayList();

        /// <summary>
        /// //定义一个公共方法Add，逐个添加客户信息
        /// </summary>
        /// <param name="cust"></param>
        public void AddCustomer(CustomerInfo cust)
        {
            customers.Add(cust);
        }
        /// <summary>
        /// //定义一个公共方法，添加一组客户信息
        /// </summary>
        /// <param name="custs"></param>
        public void AddCustomers(params CustomerInfo[] custs)
        {
            customers.AddRange(custs);
        }
        //定义一个公共方法Remove，删除指定的客户信息
        public void RemoveCustomer(CustomerInfo cust)
        {
            int index_cust = customers.IndexOf(cust);
            if (index_cust>0)
            {
                customers.RemoveAt(index_cust);
            }
        }
        public void ShowInfo()
        {
            foreach (CustomerInfo item in customers)
            {
                Console.WriteLine($"{item.ID},{item.Name},{item.CompanyName}");
            }
            Console.ReadKey();
        }
        //将Arraylist按照指定的方式排序
        public void SortByName()
        {
            //public virtual void Sort(IComparer comparer);
            //Sort方法的参数是IComparer对象，需要自己写一个比较类，实现IComaprer接口作为Sort参数
            customers.Sort(new MyCompareClass());
        }

        public void SortbyID()
        {
            //Sort方法对集合进行排序，必须确保集合的每个元素类型都实现了IComparable接口
            //这里集合的元素类型是类CustomerInfo，所以要在这个类种实现IComparable接口
            //1.类CustomerInfo继承IComparable接口；2.CustomerInfo类中实现IComparable接口的成员
            customers.Sort();
        }
        /// <summary>
        /// 升序排列
        /// </summary>
        /// <param name="obj"></param>
        /// <returns></returns>
        public int CompareTo (object obj) => this.ID.CompareTo((obj as CustomerInfo).ID);
        /// <summary>
        /// 降序排列
        /// </summary>
        /// <param name="obj"></param>
        /// <returns></returns>
        //public int CompareTo(object obj) => (obj as CustomerInfo).ID.CompareTo(this.ID);

    }
    /// <summary>
    /// 自定义一个Compare类，实现IComparer接口，即实现该接口的Compare方法int Compare(object x, object y)
    /// </summary>
    public class MyCompareClass:IComparer
    {
        //public interface IComparer
        //{
        //    int Compare(object x, object y);
        //}
        public int Compare(object cust1,object cust2)
        {
            return (cust1 as CustomerInfo).Name.CompareTo((cust2 as CustomerInfo).Name);
        }
    }
}

在Main()方法中实例化若干个客户对象，添加到集合中，并通过默认的Sort()方法和自定义的Sort（IComparer comparer）方法，实现客户信息的排序，如下代码：

    class Program
    {
        static void Main(string[] args)
        {
            CustomerInfo cust1 = new CustomerInfo("XiaoSheng", 1, "ASUS");
            CustomerInfo cust2 = new CustomerInfo("DaWang", 2, "CURTIS");
            CustomerInfo cust3 = new CustomerInfo("XiaoWang", 3, "SND YIZHONG");
            CustomerInfo cust4 = new CustomerInfo { Name = "ZhangSan", ID = 4, CompanyName = "ASDF" };
            CustomerInfo cust = new CustomerInfo();
            cust.AddCustomer(cust2);
            cust.AddCustomer(cust4);
            cust.AddCustomers(cust3, cust1);
            cust.ShowInfo();
            cust.RemoveCustomer(cust4);
            cust.ShowInfo();
            //cust.SortByName();
            cust.SortbyID();
            cust.ShowInfo();
        }
    }

客户集合默认顺序如下：

2,DaWang,CURTIS
4,ZhangSan,ASDF
3,XiaoWang,SND YIZHONG
1,XiaoSheng,ASUS

删除ID=4的客户后，显示如下：

2,DaWang,CURTIS
3,XiaoWang,SND YIZHONG
1,XiaoSheng,ASUS

按照ID排序后显示如下：
1,XiaoSheng,ASUS
2,DaWang,CURTIS
3,XiaoWang,SND YIZHONG

按照name排序后显示如下：

2,DaWang,CURTIS
1,XiaoSheng,ASUS
3,XiaoWang,SND YIZHONG