案例1：多态性
namespace e1
{
class Person { }
class Student:Person{}
class Teacher:Person{}
//多态性:含于(has a ) ; 属于(is a )
class Program
{
static void Main(string[] args)
{
/*一个基类的引用符,可以指向多种派生类对象，具有多种不同的形象，这个现象叫做多态性(Polymorphism)*/
Person p1 = new Student();
Person p2 = new Teacher();
}
}
}
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案例2 扩展性
namespace e2
{
public enum Genders{Maal,Female}
class Person
{
protected string name;
protected int age;
protected Genders genders;
public Person(string name, int age, Genders genders)
{
this.name = name;
this.age = age;
this.genders = genders;
}
}
class Student:Person
{
private string hobby;
public Student(string name,int age,Genders genders,string hobby)
:base(name,age,genders)
{
this.hobby = hobby;
}
public void SayHi()
{
Console.WriteLine("姓名:{0},年龄:{1},性别:{2},爱好:{3}",name,age,genders,hobby);
}
}
class Teacher:Person
{
private decimal salary;
public Teacher(string name, int age, Genders genders, decimal salary)
: base(name, age, genders)
{
this.salary = salary;
}
public void SayHi()
{
Console.WriteLine("姓名:{0},年龄:{1},性别:{2},工资:{3}",name,age,genders,salary);
}
}
class Program
{
static void Main(string[] args)
{
Person[] person = new Person[2];
person[0] = new Teacher("张三", 18, Genders.Maal, 5000);
person[1] = new Student("李四", 20, Genders.Female, "桌球");
//扩展的麻烦:假设我要添加班主任类,校长类,添加到该数组中,
//在以下的foreach循环中又要对班主任类,校长类进行类型判断
//扩展性非常差,为了提高程序的扩展性,我们可以使用多态的方式来解决
foreach (Person p in person)
{
if(p is Student)
{
Student stu=(Student)p;
stu.SayHi();
}
else if(p is Teacher)
{
Teacher tea=(Teacher)p;
tea.SayHi();
}
}
Console.ReadKey();
}
}
}
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案例3 抽象类多态
namespace e3
{
public enum Genders{Maal,Female}
abstract class Person
{
protected string name;
protected int age;
protected Genders genders;
public Person(string name, int age, Genders genders)
{
this.name = name;
this.age = age;
this.genders = genders;
}
//一旦定义了抽象方法,就约束了我的子类必须实现(重写)父类中的这个抽象的方法
//除非子类中的这个方法也是抽象的
public abstract void SayHi();
}
class Student:Person
{
private string hobby;
public Student(string name,int age,Genders genders,string hobby)
:base(name,age,genders)
{
this.hobby = hobby;
}
public override void SayHi()
{
Console.WriteLine("姓名:{0},年龄:{1},性别:{2},爱好:{3}", name, age, genders, hobby);
}
}
class Teacher:Person
{
private decimal salary;
public Teacher(string name, int age, Genders genders, decimal salary)
: base(name, age, genders)
{
this.salary = salary;
}
public override void SayHi()
{
Console.WriteLine("姓名:{0},年龄:{1},性别:{2},工资:{3}", name, age, genders, salary);
}
}
//抽象类不能定义给静态类(static)或者密封(sealed)类,C#中语法不被允许
//abstract static class Personq
//{
//}
class Program
{
static void Main(string[] args)
{ //抽象类不能被实例化
//可以将实现它的子类赋给抽象类引用
Person[] person = new Person[2];
person[0] = new Teacher("张三", 18, Genders.Maal, 8000);
person[1] = new Student("李四", 29, Genders.Female, "桌球");
//抽象类:abstract ,重写:override
//使用抽象类实现多态,提高了程序的可扩展性,我们无需判断父类中
//存在的具体数据是什么类型,他会根据你的具体存放的类型来掉用相应的方法
foreach (Person p in person)
{
p.SayHi();
}
//泛型集合
//List<Person> list = new List<Person>();
//list.Add(new Student("李四", 29, Genders.Female, "桌球"));
//list.Add(new Teacher("张三", 18, Genders.Maal, 8000));
//foreach (Person p in list)
//{
// p.SayHi();
//}
Console.ReadKey();
}
}
}
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案例4：
namespace e4
{
abstract class Animal
{
public abstract void SayHi();
}
class Cat : Animal
{
public override void SayHi()
{
Console.WriteLine("猫咪喵喵叫..........");
}
}
class Dog : Animal
{
public override void SayHi()
{
Console.WriteLine("狗会汪汪的叫.............");
}
}
class Frog : Animal
{
public override void SayHi()
{
Console.WriteLine("青蛙呱呱的叫.............");
}
}
class Program
{
static void Main(string[] args)
{
//多态(Polymorphism):不同对象收到相同的信息是，会产生不同行为
//Cat、Dog、Frog对象收到相同的调用信息,产生了他们各自的行为
List<Animal> list = new List<Animal>();
list.Add(new Cat());
list.Add(new Dog());
list.Add(new Frog());
foreach (Animal ani in list)
{
ani.SayHi();
}
Console.ReadKey();
}
}
}
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案例5 操作符 is， as
namespace e5
{
class Person { }
class Student : Person { }
class Teacher : Person { }
class Program
{
static void Main(string[] args)
{
//is操作符用于判断某个对象是什么类型,返回布尔值
Person p1 = new Student();
Console.WriteLine(p1 is Student);
Console.WriteLine(p1 is Teacher);
//强制转换
Student stu2 = p1 as Student;
//强制转换：一旦转换不了就会报无效的数据转换异常,程序就会中断
//Teacher tea = (Teacher)p1;
//as操作符，用于引用类型的数据类型转换
Student stu = (Student)p1;
//as操作符:一旦转换不了就会返回一个null,那么我们可以根据它的返回值来判断
//是否数据类型转换成功,不会发生异常，不会中断
Teacher tea = p1 as Teacher;
if (tea==null)
{
Console.WriteLine("无法进行转换数据类型转换.....");
}
Console.ReadKey();
}
}
}
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案例6
namespace e6
{
abstract class Cut
{
public abstract void SayHi();
}
class Barber : Cut
{
public override void SayHi()
{
Console.WriteLine("剪短头发.........");
}
}
class Doctor:Cut
{
public override void SayHi()
{
Console.WriteLine("切开皮肤.......");
}
}
class Player:Cut
{
public override void SayHi()
{
Console.WriteLine("停在表演.........");
}
}
class Program
{
static void Main(string[] args)
{
List<Cut> lc=new List<Cut>();
lc.Add(new Barber());
lc.Add(new Doctor());
lc.Add(new Player());
foreach (Cut C in lc)
{
C.SayHi();
}
Console.ReadKey();
}
}
}
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