里氏转化(向上转型)

最新推荐文章于 2022-05-26 13:51:53 发布

原创最新推荐文章于 2022-05-26 13:51:53 发布 · 243 阅读

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CC 4.0 BY-SA版权

本文通过具体的 C# 代码示例，详细解释了多态的概念及其在 C# 中的应用方式，包括虚方法的重写和新方法的声明，并展示了不同类型的对象实例在运行时如何动态调用合适的方法。

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static void Main(string[] args)
        {
            Chinese c = new Chinese();
            c.Speak();//普通话
            c.Eat();//中餐

            ShenzhenRen s = new ShenzhenRen();
            s.Speak();//粤语
            s.Eat();//粤菜
            //向上转型：
            //ch只能访问shenzhenren继承Chinese成员
            //定义父类的类型变量存储子类的对象
            Chinese ch = new ShenzhenRen();
            //继承eat(),自定义eat(),speak()
            ch.Eat();//中餐,优先调用继承的
            ch.Speak();//粤语，继承被覆盖就调用子类重写的；

        }

2.class A {
         public virtual String show(D obj)...{
                return ("A and D");
         } 
         public virtual String show(A obj)...{
                return ("A and A");
         } 
} 
class B ： A{
         public overide String show(B obj)...{
                return ("B and B");
         }
         public new String show(A obj)...{
                return ("B and A");
         } 
}
class C ： B...{} 
class D ： B...{} 

 A a1 = new A();
 A a2 = new B();
 B b = new B();
 C c = new C(); 
 D d = new D(); 
 Console.WriteLine(a1.show(b));   ①A and A
 Console.WriteLine(a1.show(c));   ②A and A
 Console.WriteLine(a1.show(d));   ③A and D
 Console.WriteLine(a2.show(b));   ④A and A
 Console.WriteLine(a2.show(c));   ⑤A and A
 Console.WriteLine(a2.show(d));   ⑥A and D
 Console.WriteLine(b.show(b));     ⑦//B and B
 Console.WriteLine(b.show(c));     ⑧//B and B
 Console.WriteLine(b.show(d));     ⑨//B and B

3.abstract calss AA{
public abstract string show1();
 }
 abstract class A:AA{
public abstract string show();
 }
 class B:A{
public overide string show(){
return "BB";
}
public overide string show1(){
return "BA";
}
 }
 class C:A{
  public overide string show(){
return "CC";
}
public overide string show1(){
return "CA";
}
 }
 class D:C{
public overide string show(){
return "DD";
}
public new string show1(){
return "DA";
}
 }

 public static void Main(){
C c=new C();
Console.WriteLine(c.show()); //CC
Console.WriteLine(c.show1());CA
A a=new C();
Console.WriteLine(a.show());CC
Console.WriteLine(a.show1());CA
D d=new D();
Console.WriteLine(d.show());DD
Console.WriteLine(d.show1());DA
C f=new D();
Console.WriteLine(f.show());//DD
Console.WriteLine(f.show1());//CA
 }