第4章 对象的筛选和排序

4.2 对象的排序

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            List<Order> list = new List<Order>();
            list.Add(new Order() { name = "a", age = 2 });
            list.Add(new Order() { name = "b", age = 1 });
            list.Add(new Order() { name = "b", age = 2 });
            List<Order.Sorter> sorterList = new List<Order.Sorter>();
            sorterList.Add(new Order.Sorter(Order.SortDirection.ASC,Order.SortField.Name));
            sorterList.Add(new Order.Sorter(Order.SortDirection.DES, Order.SortField.Age));
            list.Sort(Order.GetComparer(sorterList));
            foreach (Order item in list)
            {
                Console.WriteLine("{0}:{1}", item.name, item.age);
            }
            Console.Read();
        }
    }

    public class Order
    {
        public string name;
        public int age;

        public static OrderComparer GetComparer(List<Sorter> list)
        {
            return new OrderComparer(list);
        }

        public class OrderComparer : IComparer<Order>
        {
            private List<Sorter> list;

            public OrderComparer(List<Sorter> list)
            {
                this.list = list;
            }

            public int Compare(Order x, Order y, SortField field, SortDirection direct)
            {
                int result = 0;
                switch (field)
                {
                    case SortField.Name:
                        if (direct == SortDirection.ASC)
                            result = x.name.CompareTo(y.name);
                        else
                            result = y.name.CompareTo(x.name);
                        break;
                    case SortField.Age:
                        if (direct == SortDirection.ASC)
                            result = x.age.CompareTo(y.age);
                        else
                            result = y.age.CompareTo(x.age);
                        break;
                }
                return result;
            }

            public int Compare(Order x, Order y)
            {
                int result = 0;
                foreach (Sorter item in list)
                {
                    result = Compare(x, y, item.field, item.direct);
                    if (result != 0)
                        break;
                }
                return result;
            }
        }

        public enum SortDirection
        {
            ASC = 0,
            DES
        }

        public enum SortField
        {
            Name = 0,
            Age
        }

        public struct Sorter
        {
            public SortDirection direct;
            public SortField field;
            public Sorter(SortDirection direct, SortField field)
            {
                this.direct = direct;
                this.field = field;
            }
        }
    }
}