c#中的interface abstract与virtual介绍

public interface IPerson
{
    void getName();//不包含方法主体
}

  public interface IPerson
  {
    void getAge(string s);
  }

public interface IPerson
{
   IPerson();              //错误
   string name;            //错误
   public void getIDcard();//错误

   void getName();         //right
   void getAge(string s);  //right
}

public class Chinese:IPerson
{
   public Chinese(){}                  //添加构造
   public void getName(){}          //实现getName()
   public void getAge(string s){} //实现getAge()
}

public abstract class Book
{
  public Book()
  {  
  }

  public abstract void getPrice();      //抽象方法，不含主体
  public virtual void getName()   //虚方法，可覆盖
  {
      Console.WriteLine("this is a test:virtual getName()");
  }
  public virtual void getContent()   //虚方法，可覆盖
  {
      Console.WriteLine("this is a test:virtual getContent()");
  }
  public void getDate()                           //一般方法，若在派生类中重写，须使用new关键字
  {
      Console.WriteLine("this is a test: void getDate()");
   }
}

public class JavaBook:Book
{
      public override void getPrice()   //实现抽象方法，必须实现
      {
           Console.WriteLine("this is a test:JavaBook override abstract getPrice()");
      }
      public override void getName()   //覆盖原方法，不是必须的
      {
           Console.WriteLine("this is a test:JavaBook override virtual getName()");
      }
}

public class test
{
   public test()
   {
    JavaBook jbook=new JavaBook();
         jbook.getPrice();      //将调用JavaBook中getPrice()
         jbook.getName();       //将调用JavaBook中getName()
         jbook.getContent();    //将调用Book中getContent()
         jbook.getDate();       //将调用Book中getDate()

    }
   public static void Main()
   {

       test t=new test();
   }
}

using System;
using System.Collections.Generic;
using System.Text;
namespace ConsoleApplication3
{
    public abstract class Book
    {
        //抽象方法，不含主体，抽象方法所在类必须为抽象类，派生类必须实现该方法
        public abstract void Introduce();
    }
    public interface iBook
    {
    }
    public class JavaBook : Book
    {
        //实现抽象方法，必须实现，必须添加override关键字
        public override void Introduce()
        {
            Console.WriteLine("I'm Java");
        }
//            // Compile Error
//            public void Introduce()
//            {
//                Console.WriteLine("I'm Java");
//            }
    }

    public class test
    {
        public test()
        {
            JavaBook javaBook = new JavaBook();
            javaBook.Introduce();      //将调用JavaBook中Introduce()
            Book book = new JavaBook();
            book.Introduce();      //将调用JavaBook中Introduce()
        }
        public static void Main()
        {
            test t = new test();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Text;
namespace ConsoleApplication2
{
    public abstract class Book
    {
        public virtual void Introduce()
        {
            Console.WriteLine("I'm book");
        }
        public virtual void SayHi()
        {
            Console.WriteLine("Hi, I'm book");
        }
    }

    public class JavaBook : Book
    {
        public override void Introduce()
        {
            Console.WriteLine("I'm Java");
        }
        //注意，此方法没有override父类的方法
        public void SayHi()
        {
            Console.WriteLine("Hi, I'm Java");
        }
    }

    public class test
    {
        public test()
        {
            JavaBook javaBook = new JavaBook();
            Book book = new JavaBook();
            javaBook.Introduce();       //将调用JavaBook中Introduce()
            book.Introduce();       //将调用JavaBook中Introduce()
            javaBook.SayHi();      //将调用JavaBook中SayHi()
            book.SayHi();           //将调用Book中SayHi()
        }
        public static void Main()
        {
            test t = new test();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Text;
namespace ConsoleApplication4
{
    public abstract class Book
    {
        public void Introduce()
        {
            Console.WriteLine("I'm book");
        }
        public void SayHi()
        {
            Console.WriteLine("Hi, I'm book");
        }
    }

    public class JavaBook : Book
    {
        // 没有加new，但C#默认行为会加上new
        public void Introduce()
        {
            Console.WriteLine("I'm Java");
        }
        // 显式加上new，跟不加new实际效果一样，只是加new之后会消除compile warning
        public new void SayHi()
        {
            Console.WriteLine("Hi, I'm Java");
        }
    }

    public class test
    {
        public test()
        {
            JavaBook javaBook = new JavaBook();
            Book book = new JavaBook();
            javaBook.Introduce();       //将调用JavaBook中Introduce()
            javaBook.SayHi();           //将调用JavaBook中SayHi()

            book.Introduce();       //将调用Book中Introduce()
            book.SayHi();           //将调用Book中SayHi()
        }
        public static void Main()
        {
            test t = new test();
        }
    }
}