面向对象编程（七）接口，面向接口编程积_跬步

 1 public class InterfaceDemo{
 2     public static void main(String []args){
 3         Person p=new Person();
 4         Child child=new Child();
 5         Dog dog=new Dog();
 6         p.feed(child);
 7         p.feed(dog);
 8     }
 9 }
10 
11 class Person{
12     public void feed(Child child){
13         child.eat();
14     }
15     public void feed(Dog dog){
16         dog.eat();
17     }
18     
19 }
20 
21 interface IAbility{
22     //接口中只能放共有的静态常量和抽象方法
23     //接口中会默认public static final
24     /*public static final*/ /*int number=1;*/
25     
26     //方法中会默认加上public abstract
27     /*public abstract*/ /*void show();*/
28 }
29 
30 class Child{
31     public void eat(){
32         System.out.println("吃米饭");
33     }
34 }
35 
36 class Dog{
37     public void eat(){
38         System.out.println("啃骨头");
39     }
40 }

 1 public class InterfaceDemo{
 2     public static void main(String []args){
 3         Person p=new Person();
 4         Child child=new Child();
 5         Dog dog=new Dog();
 6         p.feed(child);
 7         p.feed(dog);
 8     }
 9 }
10 
11 class Person{
12     /*public void feed(Child child){
13         child.eat();
14     }
15     public void feed(Dog dog){
16         dog.eat();
17     }*/
18     //接口的引用变量可以引用其实现类的对象
19     //接口实现了多态
20     public void feed(IAbility ability){
21         ability.eat();//动态绑定
22     }
23     
24 }
25 
26 interface IAbility{
27     //接口中只能放共有的静态常量和抽象方法
28     //接口中会默认public static final
29     /*public static final*/ /*int number=1;*/
30     
31     //方法中会默认加上public abstract
32     /*public abstract*/ /*void show();*/
33     
34     void eat();
35 }
36 
37 class Child implements IAbility{
38     public void eat(){
39         System.out.println("吃米饭");
40     }
41 }
42 
43 class Dog implements IAbility{
44     public void eat(){
45         System.out.println("啃骨头");
46     }
47 }

 1 public class PrinterDemo{
 2     public static void main(String []args){
 3         ColorPrinter cp=new ColorPrinter("惠普");
 4         BlackPrinter bp=new BlackPrinter("戴尔");
 5         ZhenPrinter zp=new ZhenPrinter("戴尔");
 6         School school=new School();
 7         
 8         school.setPrinter(zp);//这里的参数可以调用较灵活，使用cp，bp，zp都可以，而不用改school类中的方法
 9         
10         Teacher t=new Teacher("张三",30);
11         school.print(t);
12         school.print(school); 
13     }
14 }
15 
16 interface IInfo{
17     String detail();
18 }
19 
20 abstract class Printer{
21     private String brand;
22     
23     public Printer(String brand){
24         this.brand=brand;
25     }
26     
27     public String getBrand()
28     {
29         return brand;
30     }
31     
32     //打印方法应该由其子类来具体的实现
33     public abstract void print(String content);
34 }
35 
36 //开原原则：对修改是封闭的，对扩展是开放的，不要违反开闭原则
37 //可以使用多态解决这个问题，父类的引用变量可以引用其子类的对象
38 class School implements IInfo{
39     private Printer p=null;//安装打印机
40     
41     //拿父类的引用变量作为参数，好处就是可以接受任何其子类的对象
42     //越是抽象的东西就是越稳定的
43     public void setPrinter(Printer p){
44         this.p=p;
45     }
46     //多态，程序设计时主体框架使用接口或抽象类，是程序具有很好的维护性和扩展性
47     public void print(IInfo info){
48         //交给中心所安装的打印机来打印
49         p.print(info.detail());
50     }
51     
52     public String detail(){
53         return "hello,我是学校";
54     }
55 }
56 
57 class ColorPrinter extends Printer{
58     public ColorPrinter(String brand){
59         super(brand);
60     }
61     //对父类的方法进行重写
62     public void print(String content){
63         System.out.println(getBrand()+"彩色打印:"+content);
64     }
65 }
66 
67 class BlackPrinter extends Printer{
68     public BlackPrinter(String brand){
69         super(brand);
70     }
71     //对父类的方法进行重写
72     public void print(String content){
73         System.out.println(getBrand()+"黑白打印:"+content);
74     }
75 }
76 
77 class ZhenPrinter extends Printer{
78     public ZhenPrinter(String brand){
79         super(brand);
80     }
81     //对父类的方法进行重写
82     public void print(String content){
83         System.out.println(getBrand()+"针式打印:"+content);
84     }
85 }
86 
87 class Teacher implements IInfo{
88     private String name;
89     private int age;
90     public Teacher(String name,int age){
91         this.name=name;
92         this.age=age;
93     }
94     public String detail(){
95         return "我的名字叫："+name+"，今年："+age+"岁";
96     }
97 }