c#系统泛型委托

Action<T> 无返回值的系统泛型委托

namespace ConsoleApp1
{
    public class UserInfo
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }
    class Program
    {
        private static List<UserInfo> getInit()
        {
            return new List<UserInfo>() {
                new UserInfo(){ Id=1, Name="001小王",Age=18 },
                new UserInfo (){ Id=2,Name="002大王",Age=20},
                new UserInfo (){ Id=3,Name="003笨笨",Age=21},
                new UserInfo (){ Id=4,Name="004通天塔",Age=24},
            };
        }
        static void Main(string[] args)
        {
            List<UserInfo> list = getInit();
            list.ForEach(new Action<UserInfo>(delegate (UserInfo ui) { Console.WriteLine(ui.Name); }));
            Console.WriteLine("----------------------------------------------------------------------------");
            list.ForEach(delegate (UserInfo ui) { Console.WriteLine(ui.Id+"|"+ui.Name); });
            Console.WriteLine("----------------------------------------------------------------------------");
            list.ForEach(u=> {
                Console.WriteLine(u.Id + "|" + u.Name);
            });
            Console.ReadLine();
        }
    }
}

Predicate<T> 返回bool值的系统泛型委托

namespace ConsoleApp1
{
    public class UserInfo
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }
   static  class Program
    {
        private static List<UserInfo> getInit()
        {
            return new List<UserInfo>() {
                new UserInfo(){ Id=1, Name="001小王",Age=18 },
                new UserInfo (){ Id=2,Name="002大王",Age=20},
                new UserInfo (){ Id=3,Name="003笨笨",Age=21},
                new UserInfo (){ Id=4,Name="004通天塔",Age=24},
            };
        }
        static void Main(string[] args)
        {
            #region
            List<UserInfo> list = getInit();
            list = list.FindAll(new Predicate<UserInfo>(delegate (UserInfo u) { return u.Id > 1; }));
            list.ForEach(u => {
                Console.WriteLine(u.Id + "|" + u.Name);
            });
            Console.WriteLine("----------------------------------------------------------------------------");
            list = list.FindAll(delegate (UserInfo u) { return u.Id > 2; });
            list.ForEach(u => {
                Console.WriteLine(u.Id + "|" + u.Name);
            });
            Console.WriteLine("----------------------------------------------------------------------------");
            list=list.FindAll(u => u.Id > 3);
            list.ForEach(u=> {
                Console.WriteLine(u.Id + "|" + u.Name);
            });
            #endregion

            Console.WriteLine("----------------------------自定义扩展方法---------------------------");
            List<UserInfo> listnew = list.MyFindAll<UserInfo>(delegate (UserInfo u) { return u.Id > 3; });
            listnew.ForEach(u => {
                Console.WriteLine(u.Id + "|" + u.Name);
            });
            Console.ReadLine();
        }

        static List<T> MyFindAll<T>(this List<T> list, Predicate<T> predicate)
        {
            //新集合
            List<T> newlist = new List<T>();
           //遍历老集合
            foreach (T item in list)
            {
                //如果item符合条件，则加入新集合
                if (predicate(item))
                {
                    newlist.Add(item);
                }
            }
            return newlist;
        }
    }
}

Comparison<T> 返回int类型

namespace ConsoleApp1
{
    public class UserInfo
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }
   static  class Program
    {
        private static List<UserInfo> getInit()
        {
            return new List<UserInfo>() {
                new UserInfo(){ Id=1, Name="001小王",Age=18 },
                new UserInfo (){ Id=2,Name="002大王",Age=20},
                new UserInfo (){ Id=3,Name="003笨笨",Age=21},
                new UserInfo (){ Id=4,Name="004通天塔",Age=24},
            };
        }
        static void Main(string[] args)
        {
            List<UserInfo> list = getInit();
            list.Sort(delegate (UserInfo u1, UserInfo u2) {
                return u2.Age - u1.Age;
            });
            list.ForEach(u =>
            {
                Console.WriteLine(u.Id + "|" + u.Name);
            });
            Console.ReadLine();
        }
    }
}

Func<T,TReturn> 自定义返回类型的系统泛型委托

namespace ConsoleApp1
{
    public class UserInfo
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }
    public class UserSimple
    {
        public string Name { get; set; }
    }
    static class Program
    {
        private static List<UserInfo> getInit()
        {
            return new List<UserInfo>() {
                new UserInfo(){ Id=1, Name="001小王",Age=18 },
                new UserInfo (){ Id=2,Name="002大王",Age=20},
                new UserInfo (){ Id=3,Name="003笨笨",Age=21},
                new UserInfo (){ Id=4,Name="004通天塔",Age=24},
            };
        }
        static void Main(string[] args)
        {
            List<UserInfo> list = getInit();
            IEnumerable<UserSimple> uslist = list.Select(new Func<UserInfo, UserSimple>(delegate (UserInfo u) { return new UserSimple() { Name = u.Name }; }));
            uslist.ToList().ForEach(us =>
            {
                Console.WriteLine( "|" + us.Name);
            });
            Console.WriteLine("----------------------------------------------------------------------------");
            IEnumerable<UserSimple> newuslist = list.Select(delegate (UserInfo u) { return new UserSimple() {  Name = u.Name }; });
            uslist.ToList().ForEach(us =>
            {
                Console.WriteLine( "|" + us.Name);
            });
            Console.WriteLine("-------------------------------------自定义-------------------------------");
            List<UserSimple> listnew = list.MySelect<UserInfo, UserSimple>(delegate(UserInfo u) { return new UserSimple() { Name = u.Name }; });
            listnew.ForEach(us =>
            {
                Console.WriteLine( "|" + us.Name);
            });
            Console.ReadLine();
        }
        static List<TR> MySelect<T1, TR>(this List<T1> list, Func<T1, TR> func)
        {
            List<TR> listnew = new List<TR>();
            foreach (T1 item in list)
            {
                TR tr = func(item);
                listnew.Add(tr);
            }
            return listnew;
        }
    }
}