C#中List<>的排序相关的使用方法

list的排序一般使用Sort和LINQ的Orderby方法，本文主要介绍其如何使用。

🌮1.Sort和实现Comparable接口

此方式需要类去实现IComparable接口

public  class OrderTest
{


    [Test]
    public void OraderTest()
    {
        List<ExpOne> list = new List<ExpOne>()
        {
            new ExpOne(){ NumOne = 3.12M, NumTwo = 5.54M, NumThree = 4.22M},
            new ExpOne(){ NumOne = 6.76M, NumTwo = 3.54M, NumThree = 7.67M},
            new ExpOne(){NumOne = 1.23M, NumTwo = 7.32M, NumThree = 2.85M},
            new ExpOne(){NumOne  = 2.44M, NumTwo = 1.66M,NumThree = 6.11M}
        };

        list.Sort();

        list.ForEach(item => { Console.WriteLine("值1为："+item.NumOne+" 值2为:"+item.NumTwo +" 值3为:"+item.NumThree); });
    }

    /// <summary>
    /// 用例类1
    /// </summary>
    public  class ExpOne:IComparable
    {
        /// <summary>
        /// 值一
        /// </summary>
        public decimal NumOne { get; set; }

        /// <summary>
        /// 值二
        /// </summary>
        public decimal NumTwo { get; set; }

        /// <summary>
        /// 值三
        /// </summary>
        public decimal NumThree { get; set; }

        /// <summary>
        /// 文本内容
        /// </summary>
        public string context { get; set; }

        //重写比较方法
        public int CompareTo(object obj)
        {
            ExpOne item = (ExpOne)obj;
			//这里以属性NumTwo进行排序，返回正值为this对象大于OBJ
            //返回负值为this对象小于OBJ
            if (this.NumTwo >= item.NumTwo)
                return 1;
            else
                return -1;

        }
    }
}

PS:Sort默认按Comparable的正值排序（也就是从小到大）

另外也可以不实现Comparable接口而传入一个匿名实现

[Test]
    public void OraderTest()
    {
        List<ExpOne> list = new List<ExpOne>()
        {
            new ExpOne(){ NumOne = 3.12M, NumTwo = 5.54M, NumThree = 4.22M},
            new ExpOne(){ NumOne = 6.76M, NumTwo = 3.54M, NumThree = 7.67M},
            new ExpOne(){NumOne = 1.23M, NumTwo = 7.32M, NumThree = 2.85M},
            new ExpOne(){NumOne  = 2.44M, NumTwo = 1.66M,NumThree = 6.11M}
        };

        list.Sort((left,right)=>{
            if (left.NumTwo >= right.NumTwo)
                return 1;
            else
                return -1;
        });

        list.ForEach(item => { Console.WriteLine("值1为："+item.NumOne+" 值2为:"+item.NumTwo +" 值3为:"+item.NumThree); });
    }

    /// <summary>
    /// 用例类1
    /// </summary>
    public  class ExpOne
    {
        /// <summary>
        /// 值一
        /// </summary>
        public decimal NumOne { get; set; }

        /// <summary>
        /// 值二
        /// </summary>
        public decimal NumTwo { get; set; }

        /// <summary>
        /// 值三
        /// </summary>
        public decimal NumThree { get; set; }

        /// <summary>
        /// 文本内容
        /// </summary>
        public string context { get; set; }


    }
}

效果也是一样的：

ps:Sort方法可以只对list一部分进行排序

🏀🐔2.使用LINQ进行排序

LINQ排序只需要使用OrderBy即可，功能也更加强大，同时也有几个需要注意的点。

🎤一.基础使用

public void OraderTest()
{
List<ExpOne> list = new List<ExpOne>()
{
    new ExpOne(){ NumOne = 3.12M, NumTwo = 5.54M, NumThree = 4.22M, context = "2023/06/14 09:08:02"},
    new ExpOne(){ NumOne = 6.76M, NumTwo = 3.54M, NumThree = 7.67M, context = "2023/06/14 08:46:02"},
    new ExpOne(){NumOne = 1.23M, NumTwo = 7.32M, NumThree = 2.85M,  context = "2023/06/14 10:02:45"},
    new ExpOne(){NumOne  = 2.44M, NumTwo = 1.66M,NumThree = 6.11M, context = "2023/06/14 08:39:34"}
};

list = list.OrderBy(it=>it.NumTwo).ToList();                         //根据属性值排序
list = list.OrderBy(it => Convert.ToDateTime(it.context)).ToList();  //更具转化的属性值排序
list = list.OrderBy(it => it.NumOne).ThenBy(it => it.NumTwo).ToList();                        //多个条件组合排序

list = list.OrderByDescending(it => it.NumTwo).ToList();
list = list.OrderByDescending(it => Convert.ToDateTime(it.context)).ToList();
list = list.OrderByDescending(it => it.NumOne).ThenBy(it => it.NumTwo).ToList();

list.ForEach(item => { Console.WriteLine("值1为："+item.NumOne+" 值2为:"+item.NumTwo +" 值3为:"+item.NumThree); });
}

PS:

注意一定要排序后赋值给原list,不然对原list没有效果。

注意一定要排序后赋值给原list,不然对原list没有效果。

注意一定要排序后赋值给原list,不然对原list没有效果。

🏃二.进阶使用

指定排序顺序到特定值。

有时候我们希望某个值为特定值时，将其放到特殊的位置。(毕竟特殊值不像可用于排序的基础数据类型，可以直接用于排序，像是0,1,2,3…)

[Test]
public void OraderTest()
{
    List<ExpOne> list = new List<ExpOne>()
    {
        new ExpOne(){ NumOne = 3.12M, NumTwo = 5.54M, NumThree = 4.22M, context = "艺演丁真"},
        new ExpOne(){ NumOne = 6.76M, NumTwo = 3.54M, NumThree = 7.67M, context = "轶研丁真"},
        new ExpOne(){NumOne = 1.23M, NumTwo = 7.32M, NumThree = 2.85M,  context = "尼古丁真"},
        new ExpOne(){NumOne  = 2.44M, NumTwo = 1.66M,NumThree = 6.11M, context = "芙蓉王源"}
    };
	//这里为自定义的顺序，
    List<string> MySortlist = new List<string>() { "尼古丁真","芙蓉王源","艺演丁真","轶研丁真" };

    list = list.OrderBy(it => MySortlist.IndexOf(it.context)).ToList();

    list.ForEach(item => { Console.WriteLine("值1为："+item.NumOne+" 值2为:"+item.NumTwo +" 值3为:"+item.NumThree + " 名字是:"+item.context); });
}

/// <summary>
/// 用例类1
/// </summary>
public  class ExpOne
{
    /// <summary>
    /// 值一
    /// </summary>
    public decimal NumOne { get; set; }

    /// <summary>
    /// 值二
    /// </summary>
    public decimal NumTwo { get; set; }

    /// <summary>
    /// 值三
    /// </summary>
    public decimal NumThree { get; set; }

    /// <summary>
    /// 文本内容
    /// </summary>
    public string context { get; set; }


	}
}

PS：这个顺序集合可以是从别的数据库中读取，或是别的对象中获取。重点是;你可以完全控制每个元素的位置，自定义排序规则

复杂对象的自定义排序

有些集合的Model可能有别的引用类属性，如果需要按照其进行排序可能需要自定义其规则。（需要根据具体业务来确定）

例：

public  class OrderTest
{


    [Test]
    public void OraderTest()
    {
        List<ExpOne> list = new List<ExpOne>()
        {
            new ExpOne(){ NumOne = 3.12M, NumTwo = 5.54M, NumThree = 4.22M, context = "艺演丁真", info = new InnerOne(){ Peopel_Age = 33 } },
            new ExpOne(){ NumOne = 6.76M, NumTwo = 3.54M, NumThree = 7.67M, context = "轶研丁真", info = new InnerOne(){ Peopel_Age = 24 }} ,
            new ExpOne(){NumOne = 1.23M, NumTwo = 7.32M, NumThree = 2.85M,  context = "尼古丁真", info = new InnerOne(){ Peopel_Age = 28  }},
            new ExpOne(){NumOne  = 2.44M, NumTwo = 1.66M,NumThree = 6.11M, context = "芙蓉王源",  info = new InnerOne(){ Peopel_Age = 19  }}
        };



        list = list.OrderBy(it => it.info,new CustomerComparer()).ToList();


        list.ForEach(item => { Console.WriteLine("值1为："+item.NumOne+" 值2为:"+item.NumTwo +" 值3为:"+item.NumThree + " 名字是:"+item.context +" 年龄为:"+item.info.Peopel_Age); });
    }

    /// <summary>
    /// 用例类1
    /// </summary>
    public  class ExpOne
    {
        /// <summary>
        /// 值一
        /// </summary>
        public decimal NumOne { get; set; }

        /// <summary>
        /// 值二
        /// </summary>
        public decimal NumTwo { get; set; }

        /// <summary>
        /// 值三
        /// </summary>
        public decimal NumThree { get; set; }

        /// <summary>
        /// 文本内容
        /// </summary>
        public string context { get; set; }


        public InnerOne info { get; set; }
    }

    public class InnerOne
    {
        public int Peopel_Age { get; set; }

    }

    /// <summary>
    /// 
    /// </summary>
    public class CustomerComparer : Comparer<InnerOne>
    {

        public override int Compare([AllowNull] InnerOne x, [AllowNull] InnerOne y)
        {
            if (x.Peopel_Age >= y.Peopel_Age)
                return 1;
            else
                return -1;
        }
    }
}