C#基础教程之IComparable用法,实现List<T>.sort()排序_C#教程

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 List<T>.sort()可以实现对T的排序,比如List<int>.sort()执行后集合会按照int从小到大排序。如果T是一个自定义的Object,可是我们想按照自己的方式来排序,那该怎么办呢,其实可以用过IComparable接口重写CompareTo方法来实现。流程如下:

      一.第一步我们申明一个类Person但是要继承IComparable接口:


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace TestIComparable
{
    public class Person : IComparable<Person>
    {
        public string Name { get; set; }
        public int Age { get; set; }
        public int CompareTo(Person obj)
        {
            int result;
            if (this.Name == obj.Name && this.Age == obj.Age)
            {
                result = 0;
            }
            else
            {
                if (this.Name.CompareTo(obj.Name) > 0)
                {
                    result = 1;
                }
                else if (this.Name == obj.Name && this.Age > obj.Age)
                {
                    result = 1;
                }
                else
                {
                    result = -1;
                }
            }
            return result;
        }
        public override string ToString()
        {
            return this.Name + "-" + this.Age;
        }
    }
}

  二.然后在主函数里面调用sort方法即可.类就会按照姓名从小到大,如果姓名相同则按照年龄从小到大排序了。


public class Program
{
    public static void Main(string[] args)
    {
        List<Person> lstPerson = new List<Person>();
        lstPerson.Add(new Person(){ Name="Bob",Age=19});
        lstPerson.Add(new Person(){ Name="Mary",Age=18});
        lstPerson.Add(new Person() { Name = "Mary", Age = 17 });
        lstPerson.Add(new Person(){ Name="Lily",Age=20});
        lstPerson.Sort();
        Console.ReadKey();
    }
}

   三,如果不继承IComparable接口,我们该如何实现排序呢。可以使用Linq来实现。其实效果是一样的,只是如果类的集合要经常排序的话,建议使用继承接口的方法,这样可以简化sort的代码,而且更容易让人看懂。


public static void Main(string[] args)
        {
            List<Person> lstPerson = new List<Person>();
            lstPerson.Add(new Person(){ Name="Bob",Age=19});
            lstPerson.Add(new Person(){ Name="Mary",Age=18});
            lstPerson.Add(new Person() { Name = "Mary", Age = 17 });
            lstPerson.Add(new Person(){ Name="Lily",Age=20});
            lstPerson.Sort((x,y) =>
            {
                int result;
                if (x.Name == y.Name && x.Age == y.Age)
                {
                    result = 0;
                }
                else
                {
                    if (x.Name.CompareTo(y.Name) > 0)
                    {
                        result = 1;
                    }
                    else if (x.Name == y.Name && x.Age > y.Age)
                    {
                        result = 1;
                    }
                    else
                    {
                        result = -1;
                    }
                }
                return result;
            });
            Console.ReadKey();
        }

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