Linq的Distinct

public class DA
    {
        public int ID { get; set; }
    }
    class Program
    {
        static void Main(string[] args)
        {
            var list = new List<DA>();
            var data = new DA();
            for (int i = 0; i < 10; i++)
            {
                data = new DA
                {
                    ID = i
                };
                list.Add(data);
            }
            for (int i = 0; i < 10; i++)
            {
                data = new DA
                {
                    ID = i
                };
                list.Add(data);
            }
            list = list.Select(p => new DA { ID = p.ID }).Distinct(new DAComparint()).ToList();
            Console.Read();
        }
    }

    public class DAComparint : IEqualityComparer<DA>
    {
        public bool Equals(DA x, DA y)
        {
            if (x == null && y == null)
                return false;
            return x.ID == y.ID;
        }

        public int GetHashCode(DA obj)
        {
            return obj.ToString().GetHashCode();
        }
    }

 Linq的Distinct如果针对于引用类型，需要实现IEqualityComparer接口