• c# 自定义排序Compare


    .net FrameWork 框架博大精深,用着忘着,计划对自己能够想到知识点梳理一下,此篇是对自定义排序的理解:

    class Program {
    
            static void Main(string[] args)
            {
                Random random = new Random();
                ClassA[] arr = new ClassA[10];//数组还有IEnumerator是没有实现Sort的,List实现了
    
                Console.WriteLine("Source Value:");
                for (int i = 0; i < 10; i++)
                {
                    arr[i] = new ClassA(random.Next(10), random.Next(20));
                    Console.WriteLine(arr[i].XY);
                }
                Console.WriteLine();
                Console.WriteLine("Source ToList Value:");
                var list = arr.ToList();
                for (int i = 0; i < 10; i++)
                {
                    Console.WriteLine(list[i].XY);
                }
                Console.WriteLine();
                Console.WriteLine("Source ToList Sort Value:");
                list.Sort();
                for (int i = 0; i < 10; i++)
                {
                    Console.WriteLine(list[i].XY);
                }
                Console.WriteLine();
                Console.WriteLine("Source ToList Compare Value:");
                list.Sort(new ClassAComparer());//简单实现降序
                //等同于 list.Sort((x,y)=>-x.CompareTo(y));//实现降序
                for (int i = 0; i < 10; i++)
                {
                    Console.WriteLine(list[i].XY);
                }
    
                Console.WriteLine();
                Console.WriteLine("Priority Source Value:");
                //在一些常用场景经常会有优先级的概念,针对有优先级的排序,可以参照如下:
                //Tuple<int,int> ,Item1的优先级大于Item2的优先级
                List<Tuple<int, int>> list_priority = new List<Tuple<int, int>>(10);
                for (int i = 0; i < 10; i++)
                {
                    Tuple<int, int> xy = new Tuple<int, int>(random.Next(5), random.Next(20));
                    list_priority.Add(xy);
                    Console.WriteLine(string.Format("{{X:{0},Y:{1}}}", xy.Item1, xy.Item2));
                }
    
                Console.WriteLine();
                Console.WriteLine("Priority Source Sort Value:");
                list_priority.Sort((x, y) =>
                {
                    if (x.Item1 > y.Item1)
                        return 1;
                    else if (x.Item1 == y.Item1)
                        return x.Item2 - y.Item2;
                    else
                        return -1;
                });
                for (int i = 0; i < 10; i++)
                {
                    Console.WriteLine(string.Format("{{X:{0},Y:{1}}}", list_priority[i].Item1, list_priority[i].Item2));
                }
                Console.ReadKey();
    
                //其实还有一些场景,会用到权重的概念,尤其是针对一些客户定级别时候,这个时候的排序,建议权重高的,
                //排序时候去平方,或者倍乘等方式,涉及到权重的,都是玄之又玄,出来的结果大致满意就很棒了。。。
            }
        }
    
        class ClassA:IComparable<ClassA>//定义在对象上的自定义排序,这里引用泛型,不需类型转换
        {
            public ClassA(int x, int y)
            {
                this.X = x;
                this.Y = y;
            }
            public int X { get; set; }
    
            public int Y { get; set; }
    
            public string XY
            {
                get
                {
                    return string.Format("{{X:{0},Y:{1}}}", X, Y);//C#打印大括号,左大括号{{,有大括号}}
                }
            }
    
            public int CompareTo(ClassA other)
            {
                int val = X + Y;
                int otherVal = other.X + other.Y;
                return val - otherVal;//三种结果 1,-1,0分别是大,小,相等
            }
        }
    
        class ClassAComparer : IComparer<ClassA>//单独定义的排序规则
        {
            public int Compare(ClassA x, ClassA y)
            {
                int valX = x.X + x.Y;
                int valY = y.X + y.Y;
                return valY - valX;
            }
        }

     在做一个对象集的比较时候,用到不同的比较规则,这个时候,用一个封装,如下:

     public class Compare<T> : IEqualityComparer<T>
        {
            private Func<T,T,bool> _equalsComparer;
    
            public Compare(Func<T,T,bool> equalsComparer)
            {
                this._equalsComparer = equalsComparer;
            }
    
            public bool Equals(T x, T y)
            {
                if (null != this._equalsComparer)
                    return this._equalsComparer(x, y);
                else
                    return false;
            }
    
            public int GetHashCode(T obj)
            {
                return obj.GetHashCode();
            }
        }
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  • 原文地址:https://www.cnblogs.com/lcawen/p/Compare.html
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