C# 关键字：new

Teacher t3 = new Teacher("张三", 100, 100, 100);

 1     class Person  2  {  3         public void SayHello()  4  {  5             Console.WriteLine("我是人类");  6  }  7  }  8 
 9     class Student : Person 10  { 11         public new void SayHello()//彻底隐藏了父类的SayHello()
12  { 13             Console.WriteLine("我是学生"); 14  } 15     }

 1     class Program  2  {  3         static void Main(string[] args)  4  {  5             ItemFactory<Teacher> itemFactory = new ItemFactory<Teacher>();  6             //此处编译器会检查Teacher是否具有公有的无参构造函数。
 7             Console.WriteLine($"{itemFactory.GetNewItem().Name} ID is {itemFactory.GetNewItem().Id}");  8 
 9  Console.ReadKey(); 10  } 11  } 12     public class Teacher 13  { 14         public int Id { get; set; } 15         public string Name { get; set; } 16 
17         public Teacher() 18  { 19             Id = 1; 20             Name = "张三"; 21  } 22 
23         public Teacher(int id, string name) 24  { 25             this.Id = id; 26             this.Name = name; 27  } 28  } 29 
30     class ItemFactory<T> where T : new() 31  { 32         public T GetNewItem() 33  { 34             return new T(); 35  } 36     }