IEqualityComparer<T>接口

IEqualityComparer<T>接口的对象的主要作用在于自定义判断两个对象是否相等。

其中最常用的方法： bool Equals(T x, T y);

实现该方法用于比较两个对象是否相等。如果指定的对象相等，则为 true；否则为 false。

代码示例：

    class Program
    {
        static void Main(string[] args)
        {
            People p1 = new People(1, "刘备", 23);
            People p2 = new People(1, "关羽", 22);
            People p3 = new People(1, "张飞", 21);
            List<People> listP1 = new List<People>();
            listP1.Add(p1);
            listP1.Add(p2);
            listP1.Add(p3);

            People p4 = new People(2, "赵云", 23);
            People p5 = new People(2, "黄忠", 22);
            People p6 = new People(2, "马超", 21);
            List<People> listP2 = new List<People>();
            listP2.Add(p4);
            listP2.Add(p5);
            listP2.Add(p6);

            Comparers c = new Comparers();
            bool b = listP1.SequenceEqual(listP2, c);   //只要集合中的对象年龄相等就视对象为相等
            Console.WriteLine(b);   //输出 True

            Console.ReadKey();
        }
    }

    public class Comparers : IEqualityComparer<People>
    {

        public bool Equals(People p1, People p2)
        {
            if (p1.Age == p2.Age)
            {
                return true;
            }
            return false;
        }

        public int GetHashCode(People obj)
        {
            throw new NotImplementedException();
        }
    }

    public class People
    {
        public People(int id, string name, int age)
        {
            this.Id = id;
            this.Name = name;
            this.Age = age;
        }

        public int Id
        {
            get;
            set;
        }

        public string Name
        {
            get;
            set;
        }

        public int Age
        {
            get;
            set;
        }
    }