using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace MyGeneric.CC{ /// /// 只能放在接口或者委托的泛型参数前面 /// out 协变covariant 修饰返回值 /// in 逆变contravariant 修饰传入参数 /// public class CCTest { public static void Show() { { Bird bird1 = new Bird(); Bird bird2 = new Sparrow(); Sparrow sparrow1 = new Sparrow(); //sparrow sparrow2 = new bird(); } { List birdList1 = new List (); //List birdList2 = new List ();//两个list泛型实例不存在继承关系 List birdList3 = new List ().Select(c => (Bird)c).ToList(); } { IEnumerable birdList1 = new List (); IEnumerable birdList2 = new List (); //Action //Func } { ICustomerListOut customerList1 = new CustomerListOut (); ICustomerListOut customerList2 = new CustomerListOut (); } { ICustomerListIn customerList2 = new CustomerListIn (); ICustomerListIn customerList1 = new CustomerListIn (); ICustomerListIn birdList1 = new CustomerListIn (); birdList1.Show(new Sparrow()); birdList1.Show(new Bird()); } { IMyList myList1 = new MyList (); IMyList myList2 = new MyList ();//协变 IMyList myList3 = new MyList ();//逆变 IMyList myList4 = new MyList ();//协变+逆变 } } } public class Bird { public int Id { get; set; } } public class Sparrow : Bird { public string Name { get; set; } } public interface ICustomerListIn { //T Get(); void Show(T t); } public class CustomerListIn : ICustomerListIn { //public T Get() //{ // return default(T); //} public void Show(T t) { } } /// /// out 协变 只能是返回结果 /// /// public interface ICustomerListOut { T Get(); //void Show(T t); } public class CustomerListOut : ICustomerListOut { public T Get() { return default(T); } //public void Show(T t) //{ //} } public interface IMyList { void Show(inT t); outT Get(); outT Do(inT t); ////out 只能是返回值 in只能是参数 //void Show1(outT t); //inT Get1(); } public class MyList : IMyList { public void Show(T1 t) { Console.WriteLine(t.GetType().Name); } public T2 Get() { Console.WriteLine(typeof(T2).Name); return default(T2); } public T2 Do(T1 t) { Console.WriteLine(t.GetType().Name); Console.WriteLine(typeof(T2).Name); return default(T2); } }}
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace MyGeneric{ public class Constraint { /// /// 泛型约束，基类约束： /// 1 在泛型方法内可以直接使用基类的属性和方法 /// 2 调用的时候，只能传递基类或者基类的子类 /// /// /// public static void Show (T tParameter) where T : People, IWork { Console.WriteLine("This is {0},parameter={1},type={2}", typeof(GenericMethod), tParameter.GetType().Name, tParameter.ToString()); //((People)tParameter).Id //tParameter. Console.WriteLine("id={0} name={1}", tParameter.Id, tParameter.Name); tParameter.Hi(); tParameter.Work(); //tParameter.Id //tParameter.Name } private void Linq() { } public static void ShowPeople(People tParameter) { Console.WriteLine("This is {0},parameter={1},type={2}", typeof(GenericMethod), tParameter.GetType().Name, tParameter.ToString()); //((People)tParameter).Id //tParameter. Console.WriteLine("id={0} name={1}", tParameter.Id, tParameter.Name); tParameter.Hi(); //tParameter.Work(); //tParameter.Id //tParameter.Name } public static void ShowInterface (T tParameter) where T : ISports { tParameter.Pingpang(); } public static T Get (T tParameter) //where T : new()//无参数构造 //where T : class//引用类型 //where T : struct//值类型 { //T t = new T(); //return t; //return null; return default(T); //return tParameter; } /// /// 多重约束，，是而且的关系 and /// /// public static void Many () where T : class, ISports, IWork, new() { } }}
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace MyGeneric{ public class GenericClass { public void Show(T t) { Console.WriteLine(t); } public void GenericMethod () { } public T Get(T t) { List iList = null; return t; } } public interface IGet { } public delegate void GetHandler (); public class ChildClass : GenericClass , IGet { } public class ChildClass : GenericClass , IGet { private Child child = new Child(); } public class Parent { public Parent(string name) { } } public class Child : Parent { public Child():base("123") { } }}
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace MyGeneric{ public class GenericMethod { /// /// 延迟声明：把参数类型的声明推迟到调用 /// 不是语法糖，而是由框架升级提供的功能 /// /// /// public static void Show (T tParameter) { Console.WriteLine("This is {0},parameter={1},type={2}", typeof(GenericMethod), tParameter.GetType().Name, tParameter.ToString()); } /// /// 打印个object值 /// 1 任何父类出现的地方，都可以使用子类来替换 /// 2 object是一切类型的父类 /// /// public static void ShowObject(object oParameter) { Console.WriteLine("This is {0},parameter={1},type={2}", typeof(GenericMethod), oParameter.GetType().Name, oParameter); } }}
using System;using System.Collections.Generic;using System.Diagnostics;using System.Linq;using System.Text;using System.Threading.Tasks;namespace MyGeneric{ /// /// 1 引入泛型:延迟声明 /// 2 如何声明和使用泛型 /// 3 泛型的好处和原理 /// 4 泛型类、泛型方法、泛型接口、泛型委托 /// 5 泛型约束 /// 6 协变 逆变(选修) /// class Program { static void Main(string[] args) { try { //var list = new List () { 1, 2, 3, 4 } //.Select(i => new //{ // id = i, // name = "Test" + i //}); //foreach (var item in list) //{ // Console.WriteLine(item.id); // Console.WriteLine(item.name); //} //List Console.WriteLine("============================今天是泛型Generic课程================================="); int iValue = 123; string sValue = "456"; DateTime dtValue = DateTime.Now; object oValue = new object(); Console.WriteLine(typeof(List )); Console.WriteLine(typeof(Dictionary )); Console.WriteLine("**************************"); CommonMethod.ShowInt(iValue); //CommonMethod.ShowInt(sValue); CommonMethod.ShowString(sValue); CommonMethod.ShowDateTime(dtValue); Console.WriteLine("**************************"); CommonMethod.ShowObject(oValue); CommonMethod.ShowObject(iValue); CommonMethod.ShowObject(sValue); CommonMethod.ShowObject(dtValue); Console.WriteLine("**************************"); GenericMethod.Show
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace MyGeneric{ public interface ISports { void Pingpang(); } public interface IWork { void Work(); } public class People { public int Id { get; set; } public string Name { get; set; } public void Hi() { } } public class Chinese : People, ISports, IWork { public string Tradition { get; set; } public void SayHi() { Console.WriteLine("吃了么？"); } public void Pingpang() { Console.WriteLine("打乒乓球..."); } public void Work() { throw new NotImplementedException(); } } public class Hubei : Chinese { public string Changjiang { get; set; } public void Majiang() { Console.WriteLine("打麻将啦。。"); } } public class Japanese : ISports { public int Id { get; set; } public string Name { get; set; } public void Pingpang() { Console.WriteLine("打乒乓球..."); } }}