C#面向对象基础(六) 继承

继承 

描述的是 is a kind of 的关系.

比如:Animal类  wolf类.  Wolf类是Animal类的子类,Animal类是父类.Wolf类从Animal类派生,Wolf类继承了Animal类

Wolf是一种Animal. 

失败的设计:

 1  public class Wolf
 2     {
 3         public string name;
 4         public int age;
 5         public bool ishungry;
 6         private int weight;
 7         public void Sleep()
 8         {
 9             Console.WriteLine("睡觉..."); 
10         }
11         public void Eat()
12         {
13             Console.WriteLine("吃羊...");
14         }
15     }
16     public class Goat 
17     {
18         public string name;
19         public int age;
20         public bool ishungry;
21         private int weight;
22         public void Sleep()
23         {
24             Console.WriteLine("睡觉..."); 
25         }
26         public void Eat()
27         {
28             Console.WriteLine("吃草...");
29         }
30     }

用到了继承很好的设计!

class Animal
    {
        public string name;
        public int age;
        public bool ishungry;
        private int weight;
        public void Sleep()
        {
            Console.WriteLine("睡觉..."); 
        }
    }
    public class Wolf : Animal
    {
        public void Eat()
        {
            Console.WriteLine("吃羊...");
        }
    }
    public class Goat : Animal
    {
        public void Eat()
        {
            Console.WriteLine("吃草...");
        }
    }

访问控制修饰符

public 公开的,谁想访问都可以.

private 私有的,类内部访问

proteced  受保护的,子类可以访问.

默认private

密封类

sealed!

 public class Animal
    {
        public string name;
        public int age;
        public bool ishungry;
        protected int weight;
      
        public Animal(string n,int a)
        {
            name = n;
            age = a;
            Console.WriteLine("Animal构造方法"); 
        }
        public void Sleep()
        {
            Console.WriteLine("睡觉...");            
        }
    }
    public class Wolf : Animal
    {
        public Wolf():base("noname",1)
        { }
        public Wolf(string n):base(n,1)
        { 
        }
        public Wolf(string n, int a):base(n,a)
        {
            Console.WriteLine("Wolf构造方法");
        }
        public new void Sleep()
        {
            Console.WriteLine("Wolf睡觉...");  
        }
        public void Eat()
        {
            Console.WriteLine("吃羊...");
            base.Sleep();
        }
    }