第二章：面向对象

一、对象的封装

1. 类和对象

1.1 类

image.png

1.2 对象

万物皆对象，客观存在的事物即为对象

1.3 对象的属性

对象的各种特征，每个对象的每个属性都有着特定的值

1.4 对象的行为

对象能够执行的操作

1.5 类和对象的关系

类是对象的抽象分类
对象是类的实体

1.6 类的定义

image.png

  1.     //类
  2. public class Phone(){
  3.     //成员变量
  4.     String brand;
  5.     int price;
  7.     //成员方法
  8.     public void call(){
  9.         System.out.println{"打电话"};
  10.     }
  11.     public void sendMessage(){
  12.         System.out.println("发短信");
  13.     }
  14. }

1.9 对象的使用

image.png

  1. //注意对象和类是结合使用的
  2. public class PhoneDemo(){
  3.     public static void main(String[] args){
  4.         //-----------------成员变量的使用
  5.         //创建对象
  6.         Phone p = new Phone();
  8.         //使用对象
  9.         System.out.println(p.brand);
  10.         System.out.println(p.price);
  12.         //变量赋值
  13.         p.brand = "小米";
  14.         p.price = 59999;
  16.         System.out.println(p.brand);
  17.         System.out.println(p.price);
  18.         //------------------成员方法的使用
  19.         //使用成员方法
  20.         p.call();
  21.         p.sendMessage();
  22.     }
  23. }

2.0 案例学生类的定义和使用

  1. //--------------------------------------------------学生类
  2. package com.iteima_01;
  4. public class Student {
  5.     //成员变量
  6.     String name;
  7.     int age;
  9.     //成员方法
  10.     public void study(){
  11.         System.out.println("好好学习，天天向上");
  12.     }
  13.     public void doHomework(){
  14.         System.out.println("键盘敲烂，月薪过万");
  15.     }
  16. }
  17. //--------------------------------------------------学生类的使用
  18. package com.iteima_01;
  19. //学生测试类
  20. public class StudentDemo {
  21.     public static void main(String[] args){
  22.         //创建对象
  23.         Student s = new Student();
  25.         //使用对象
  26.         System.out.println(s.name+","+s.age);
  28.         s.name = "马云";
  29.         s.age = 44;
  31.         System.out.println(s.name+","+s.age);
  33.         //使用方法
  34.         s.study();
  35.         s.doHomework();
  36.     }
  37. }

2.1 成员变量和局部变量的含义

image.png

2.2 成员变量和局部变量的区别

image.png

二、对象的继承

1. 继承

image.png
image.png

1. 案例

  1. //--------------------------------------这是父类
  2. package com.iteima_01;
  4. public class Fu {
  5.     public void call(){
  6.         System.out.println("Fu方法被调用");
  7.     }
  8. }
  9. //--------------------------------------这是子类
  10. package com.iteima_01;
  12. public class Zi extends Fu{
  13.     public void test(){
  14.         System.out.println("这是Zi方法");
  15.     }
  16. }
  17. //--------------------------------------这是main方法测试类
  18. package com.iteima_01;
  20. public class Demo {
  21.     public static void main(String[] args) {
  22.         Fu f = new Fu();
  23.         Zi z = new Zi();
  25.         f.call();
  26.         z.test();
  27.         z.call();
  28.     }
  29. }

2. 继承的好处和弊端

image.png

3. 继承中变量的访问特点

1. 继承中变量的访问顺序

image.png

2. 继承中 this super 的使用方法

image.png

  1. //--------------------------------------这是父类
  2. package com.iteima_01;
  4. public class Fu {
  5.     int a = 30;
  6.     public void call(){
  7.         System.out.println("Fu方法被调用");
  8.     }
  9. }
  10. //--------------------------------------这是子类
  11. package com.iteima_01;
  12. int a = 20;
  13. public class Zi extends Fu{
  14.     public void test(){
  15.         int a = 10;
  16.         System.out.println("这是访问局部变量a"+a);
  17.         System.out.println("这是访问子类变量a"+this.a);
  18.         System.out.println("这是访问父类变量a"+super.a);
  19.     }
  20. }

3. 继承中构造方法的访问特点

image.png

4. 继承中成员方法的访问特点

image.png

5. 方法重写

image.png

  1. //--------------------------------------这是父类
  2. package com.iteima_01;
  4. public class Fu {
  5.     public void call(String name){
  6.         System.out.println("给"+name+"打电话");
  7.     }
  8. }
  9. //--------------------------------------这是子类
  10. package com.iteima_01;
  12. public class Zi extends Fu{
  13.     @Override
  14.     public void call(String name){
  15.         System.out.println("开启视频通话功能");
  16.         super.call(name);
  17.     }
  18. }
  19. //--------------------------------------这是main方法测试类
  20. package com.iteima_01;
  22. public class Demo {
  23.     public static void main(String[] args) {
  24.         Fu f = new Fu();
  25.         f.call("马云");
  26.         System.out.println("---------");
  28.         Zi z = new Zi();
  29.         z.call("马云");
  30.     }
  31. }
  • 私有方法不能被重写（父类的私有成员子类是不能被继承的）
  • 方法重写的时候，子类的方法权限不能低于父类（public > 默认 > 私有）

    6. Java继承的注意事项

    image.png
    image.png

    7. 案例 老师和学生 super传参

    ```java //——————————————————————————人类 package com.iteima_01;

public class People { private String name; private int age;

  1. public People() {
  2. }
  4. public People(int age, String name) {
  5.     this.age = age;
  6.     this.name = name;
  7. }
  9. public int getAge() {
  10.     return age;
  11. }
  13. public void setAge(int age) {
  14.     this.age = age;
  15. }
  17. public String getName() {
  18.     return name;
  19. }
  21. public void setName(String name) {
  22.     this.name = name;
  23. }

} //——————————————————————————老师类 package com.iteima_01;

public class Teacher extends People { public Teacher(){}

  1. public Teacher(String name,int age) {
  2.     super(age, name);
  3. }
  5. public void teach(){
  6.     System.out.println("用爱成就每一位学员");
  7. }

} //——————————————————————————学生类 package com.iteima_01;

public class Student extends Teacher{ public Student(){} public Student(String name,int age){ super(name, age); } public void study(){ System.out.println(“好好学习，天天向上”); } } //——————————————————————————测试类 package com.iteima_01;

public class Demo { public static void main(String[] args) { //无参老师类 Teacher t1 = new Teacher(); t1.setName(“武当王也”); t1.setAge(18); System.out.println(t1.getName()+”,”+t1.getAge()); t1.teach();

  1.     //带参老师类
  2.     Teacher t2 = new Teacher("校长",20);
  3.     System.out.println(t2.getName()+","+t2.getAge());
  4.     t2.teach();
  5.     System.out.println("-------------------我是分割线-----------------------");
  7.     //无参学生类
  8.     Student s1 = new Student();
  9.     s1.setName("全性龚庆");
  10.     s1.setAge(15);
  11.     System.out.println(s1.getName()+","+s1.getAge());
  12.     s1.study();
  13.     //带参学生类
  14.     Student s2 = new Student("学生",13);
  15.     System.out.println(s2.getName()+","+s2.getAge());
  16.     s2.study();
  18. }

}

  1. <a name="oLZSi"></a>
  2. #### 8. 案例 猫和狗 super传参
  3. ```java
  4. //----------------------------------------------------动物类
  5. package com.iteima_01;
  6. //这是动物类
  7. public class People {
  8.     private String name;
  9.     private int age;
  11.     public People() {
  12.     }
  14.     public People(String name, int age) {
  15.         this.age = age;
  16.         this.name = name;
  17.     }
  19.     public int getAge() {
  20.         return age;
  21.     }
  23.     public void setAge(int age) {
  24.         this.age = age;
  25.     }
  27.     public String getName() {
  28.         return name;
  29.     }
  31.     public void setName(String name) {
  32.         this.name = name;
  33.     }
  34. }
  35. //----------------------------------------------------猫类
  36. package com.iteima_01;
  37. //这是猫类
  38. public class Teacher extends People{
  39.     public Teacher(){}
  41.     public Teacher(String name,int age){
  42.         super (name,age);
  43.     }
  45.     public void cat() {
  46.         System.out.println("我会抓老鼠");
  47.     }
  48. }
  49. //----------------------------------------------------测试类
  50. package com.iteima_01;
  52. public class Demo {
  53.     public static void main(String[] args) {
  54.         //无参猫类
  55.         Teacher t1 = new Teacher();
  56.         t1.setName("黑猫");
  57.         t1.setAge(6);
  58.         System.out.println(t1.getName()+","+t1.getAge());
  59.         t1.cat();
  61.         //带参猫类
  62.         Teacher t2 = new Teacher("白猫",8);
  63.         System.out.println(t2.getName()+","+t2.getAge());
  64.         t2.cat();
  65.     }
  66. }

4. package 包

1. 包的概述和创建

image.png

2. 导包

image.png

3. 权限修饰符 默认、private、protected、public

image.png

  1. package com.iteima_01;
  3. public class People{
  4.     private void show1(){
  5.         System.out.println("private");
  6.     }
  7.     void show2(){
  8.         System.out.println("默认");
  9.     }
  10.     protected void show3(){
  11.         System.out.println("protected");
  12.     }
  13.     public void show4(){
  14.         System.out.println("public");
  15.     }
  16. }

4. final修饰局部变量

image.png

  1. package com.iteima_01;
  3. public class Demo {
  4.     public static void main(String[] args) {
  5.         //final修饰局部变量
  6.         final int a = 10;
  7.         System.out.println("这是赋值前局部变量"+a);
  8. //        a = 100;
  9.         System.out.println("这是赋值后局部变量"+a);
  11.         //final修饰引用变量
  12.         final Teacher t = new Teacher();
  13.         System.out.println("这是赋值前引用变量"+t.a);
  14.         t.a = 200;
  15.         System.out.println("这是赋值后引用变量"+t.a);
  17. //        t = new Teacher();
  18.     }
  19. }

5. static

image.png

  1. package com.iteima_01;
  3. public class Teacher {
  4.     public String name;
  5.     public int age;
  6.     public static String from;
  7.     public void show(){
  8.         System.out.println(name+","+age+","+from);
  9.     }
  10. }
  12. //----------------------------------------------------测试类
  13. package com.iteima_01;
  15. public class Demo {
  16.     public static void main(String[] args) {
  17.         Teacher.from = "China";
  18.         Teacher t = new Teacher();
  19.         t.name = "张三";
  20.         t.age = 20;
  21. //        t.from = "China";
  22.         t.show();
  24.         Teacher t2 = new Teacher();
  25.         t2.name = "李四";
  26.         t2.age = 22;
  27. //        t.from = "China";
  28.         t2.show();
  29.     }
  30. }

6. static的访问特点

  • 静态成员方法只能访问静态成员
  • 非静态成员能访问所有的成员

    5. 多态

    1. 多态的简介案例

    image.png ```java //——————————————————————————父类 package com.iteima_01;

public class Fu { public void eat(){ System.out.println(“我是父类猫”); } } //——————————————————————————子类 package com.iteima_01;

public class Zi extends Fu{ @Override public void eat() { System.out.println(“子类的猫会吃鱼”); } } //——————————————————————————测试类 package com.iteima_01;

public class Demo { public static void main(String[] args) { Fu f = new Zi(); f.eat(); } }

  1. <a name="dBy1t"></a>
  2. #### 2. 多态的访问特点
  3. ![image.png](https://cdn.nlark.com/yuque/0/2021/png/5358492/1618149595818-34ce2773-3a0a-4686-a8d6-8d1315eb06ae.png#align=left&display=inline&height=163&id=lmRbU&margin=%5Bobject%20Object%5D&name=image.png&originHeight=163&originWidth=382&size=57136&status=done&style=none&width=382)
  4. <a name="SwCcu"></a>
  5. #### 3. 多态的好处和弊端
  6. ![image.png](https://cdn.nlark.com/yuque/0/2021/png/5358492/1618150103112-cb4d9383-9115-42d0-ad22-5aa3edb3e39c.png#align=left&display=inline&height=90&id=lkdGu&margin=%5Bobject%20Object%5D&name=image.png&originHeight=90&originWidth=820&size=52785&status=done&style=none&width=820)
  7. <a name="ACeXY"></a>
  8. #### 4. 多态的转型
  9. ![image.png](https://cdn.nlark.com/yuque/0/2021/png/5358492/1618150308544-e152a7d4-db45-49a5-80d7-f32b8469cc80.png#align=left&display=inline&height=194&id=kmz8g&margin=%5Bobject%20Object%5D&name=image.png&originHeight=194&originWidth=229&size=27994&status=done&style=none&width=229)
  10. ```java
  11. //----------------------------------------------------父类
  12. package com.iteima_01;
  14. public class Fu {
  15.     public void eat(){
  16.         System.out.println("我是父类猫");
  17.     }
  18. }
  19. //----------------------------------------------------子类
  20. package com.iteima_01;
  22. public class Zi extends Fu{
  23.     @Override
  24.     public void eat() {
  25.         System.out.println("子类的猫会吃鱼");
  26.     }
  28.     public void game(){
  29.         System.out.println("子类的猫会玩游戏");
  30.     }
  31. }
  32. //----------------------------------------------------测试类
  33. package com.iteima_01;
  35. public class Demo {
  36.     public static void main(String[] args) {
  37.         //向上转型
  38.         Fu f = new Zi();
  39.         f.eat();
  40.         //向下转型
  41.         Zi z = (Zi) f;
  42.         z.eat();
  43.         z.game();
  44.     }
  45. }

5. 案例 猫和狗 多态继承的方法

  1. //-------------------------------------------------父类
  2. package com.iteima_01;
  4. public class Fu {
  5.     private String name;
  6.     private int age;
  8.     public Fu() {}
  9.     public Fu(String name,int age){
  10.         this.name = name;
  11.         this.age = age;
  12.     }
  14.     public String getName() {
  15.         return name;
  16.     }
  18.     public void setName(String name) {
  19.         this.name = name;
  20.     }
  22.     public int getAge() {
  23.         return age;
  24.     }
  26.     public void setAge(int age) {
  27.         this.age = age;
  28.     }
  30.     public void eat(){
  31.         System.out.println("父类吃饭");
  32.     }
  33. }
  34. //-------------------------------------------------子类
  35. package com.iteima_01;
  37. public class Zi extends Fu{
  38.     public Zi() {
  39.     }
  41.     public Zi(String name, int age) {
  42.         super(name, age);
  43.     }
  45.     @Override
  46.     public void eat() {
  47.         System.out.println("子类的猫会玩游戏");
  48.     }
  49. }
  50. //-------------------------------------------------测试类
  51. package com.iteima_01;
  53. public class Demo {
  54.     public static void main(String[] args) {
  55.         Fu f = new Zi();
  56.         f.setAge(5);
  57.         f.setName("黑猫");
  58.         System.out.println(f.getName()+","+f.getAge());
  59.         f.eat();
  61.         f = new Zi("白猫",4);
  62.         System.out.println(f.getName()+","+f.getAge());
  63.         f.eat();
  65.     }
  66. }

6. 抽象类 abstract

image.png

7. 抽象类的特点

image.png

8. 抽象类成员的特点

image.png

9. 案例 猫和狗 抽象类的使用

  1. //-------------------------------------------------父类
  2. package com.iteima_01;
  4. public abstract class Fu {
  5.     private String name;
  6.     private int age;
  8.     public Fu() {
  9.     }
  11.     public Fu(String name, int age) {
  12.         this.name = name;
  13.         this.age = age;
  14.     }
  16.     public String getName() {
  17.         return name;
  18.     }
  20.     public void setName(String name) {
  21.         this.name = name;
  22.     }
  24.     public int getAge() {
  25.         return age;
  26.     }
  28.     public void setAge(int age) {
  29.         this.age = age;
  30.     }
  32.     public abstract void eat();
  33. }
  34. //-------------------------------------------------子类
  35. package com.iteima_01;
  37. public class Zi extends Fu{
  38.     public Zi() {
  39.     }
  41.     public Zi(String name, int age) {
  42.         super(name, age);
  43.     }
  45.     @Override
  46.     public void eat() {
  47.         System.out.println("子类的猫会晒太阳");
  48.     }
  49. }
  50. //-------------------------------------------------测试类
  51. package com.iteima_01;
  53. public class Demo {
  54.     public static void main(String[] args) {
  55.         Fu f = new Zi();
  56.         f.eat();
  57.         f.setName("黑猫");
  58.         f.setAge(4);
  59.         System.out.println(f.getName()+","+f.getAge());
  61.         f = new Zi("白猫",5);
  62.         System.out.println(f.getName()+","+f.getAge());
  63.         f.eat();
  66.     }
  67. }

6. 接口 interface implements

1.描述

image.png

2. 接口的特点

image.png

3. 接口成员的特点

image.png

4. 案例 猫和狗 接口的使用

  1. //------------------------------------------------------主类
  2. package com.iteima_02;
  4. public interface Jumpping{
  5.     public abstract void jump();
  6. }
  7. //------------------------------------------------------动物类
  8. package com.iteima_02;
  10. public abstract class Animal {
  11.     private String name;
  12.     private int age;
  14.     public String getName() {
  15.         return name;
  16.     }
  18.     public void setName(String name) {
  19.         this.name = name;
  20.     }
  22.     public int getAge() {
  23.         return age;
  24.     }
  26.     public void setAge(int age) {
  27.         this.age = age;
  28.     }
  30.     public Animal(String name, int age) {
  31.         this.name = name;
  32.         this.age = age;
  33.     }
  35.     public Animal() {
  36.     }
  38.     public abstract void eat();
  39. }
  40. //------------------------------------------------------猫类
  41. package com.iteima_02;
  43. public class Cat extends Animal implements Jumpping{
  44.     @Override
  45.     public void eat() {
  46.         System.out.println("猫吃鱼");
  47.     }
  49.     @Override
  50.     public void jump() {
  51.         System.out.println("猫会跳高");
  52.     }
  54.     public Cat(String name, int age) {
  55.         super(name, age);
  56.     }
  58.     public Cat() {
  59.     }
  60. }
  61. //------------------------------------------------------测试类
  62. package com.iteima_02;
  64. public class Demo {
  65.     public static void main(String[] args) {
  66.         Jumpping j = new Cat();
  67.         j.jump();
  69.         Animal a = new Cat();
  70.         a.setName("黑猫");
  71.         a.setAge(6);
  72.         System.out.println(a.getName()+","+a.getAge());
  73.         a.eat();
  75.         a = new Cat("白猫",4);
  76.         System.out.println(a.getName()+","+a.getAge());
  77.         a.eat();
  78.     }
  79. }

5. 类和接口的关系

image.png

6. 抽象类和接口的区别

image.png

7. 案例 运动员和教练

image.png

  1. //------------------------------------------------------------------------学英语接口
  2. package Demo;
  4. public interface LeanEnglish {
  5.     public void speakEnglish();
  6. }
  7. //------------------------------------------------------------------------人总类
  8. package Demo;
  10. public abstract class Ren {
  11.     private int age;
  12.     private String name;
  14.     public Ren(int age, String name) {
  15.         this.age = age;
  16.         this.name = name;
  17.     }
  19.     public Ren() {
  20.     }
  22.     public int getAge() {
  23.         return age;
  24.     }
  26.     public void setAge(int age) {
  27.         this.age = age;
  28.     }
  30.     public String getName() {
  31.         return name;
  32.     }
  34.     public void setName(String name) {
  35.         this.name = name;
  36.     }
  38.     public void each(){
  39.         System.out.println("我是人类吃饭");
  40.     }
  41. }
  42. //------------------------------------------------------------------------学生类
  43. package Demo;
  45. public abstract class Study extends Ren{
  46.     public Study() {
  47.     }
  49.     public Study(int age, String name) {
  50.         super(age, name);
  51.     }
  53.     public void xue(){
  54.         System.out.println("我是学生类");
  55.     }
  56. }
  57. //------------------------------------------------------------------------老师类
  58. package Demo;
  60. public abstract class Teach extends Ren{
  61.     public Teach(int age, String name) {
  62.         super(age, name);
  63.     }
  65.     public Teach() {
  66.     }
  68.     public void jiao(){
  69.         System.out.println("我是老师类");
  70.     }
  71. }
  72. //------------------------------------------------------------------------篮球老师类
  73. package Demo;
  75. public class Lteacher extends Teach{
  76.     public Lteacher(int age, String name) {
  77.         super(age, name);
  78.     }
  80.     public Lteacher() {
  81.     }
  83.     @Override
  84.     public void jiao() {
  85.         System.out.println("我是篮球教练，我教悠悠球");
  86.     }
  88.     @Override
  89.     public void each() {
  90.         System.out.println("我是篮球教练，我吃奶");
  91.     }
  92. }
  93. //------------------------------------------------------------------------乒乓球老师类
  94. package Demo;
  96. public class Pteacher extends Teach implements LeanEnglish{
  97.     public Pteacher(int age, String name) {
  98.         super(age, name);
  99.     }
  101.     public Pteacher() {
  102.     }
  104.     @Override
  105.     public void each() {
  106.         System.out.println("我是乒乓球教练，我教国足");
  107.     }
  109.     @Override
  110.     public void jiao() {
  111.         System.out.println("我是乒乓球教练，我吃肉");
  112.     }
  114.     @Override
  115.     public void speakEnglish() {
  116.         System.out.println("我是乒乓球教练，我教英语");
  117.     }
  118. }
  119. //------------------------------------------------------------------------篮球学生类
  120. package Demo;
  122. public class Lstudent extends Study{
  123.     public Lstudent() {
  124.     }
  126.     public Lstudent(int age, String name) {
  127.         super(age, name);
  128.     }
  130.     @Override
  131.     public void each() {
  132.         System.out.println("我是篮球运动员，我吃屎");
  133.     }
  135.     @Override
  136.     public void xue() {
  137.         System.out.println("我是篮球运动员，我学打篮球");
  138.     }
  139. }
  140. //------------------------------------------------------------------------乒乓球学生类
  141. package Demo;
  143. public class Pstudent extends Study implements LeanEnglish{
  144.     public Pstudent() {
  145.     }
  147.     public Pstudent(int age, String name) {
  148.         super(age, name);
  149.     }
  151.     @Override
  152.     public void each() {
  153.         System.out.println("我是乒乓球运动员，我吃求");
  154.     }
  156.     @Override
  157.     public void xue() {
  158.         System.out.println("我是乒乓球运动员，我学打乒乓球");
  159.     }
  161.     @Override
  162.     public void speakEnglish() {
  163.         System.out.println("我是乒乓球运动员，我学习说英语");
  164.     }
  165. }
  166. //------------------------------------------------------------------------测试类
  167. package Demo;
  168. //测试类
  169. public class Demo {
  170.     public static void main(String[] args) {
  171.         //测试乒乓球
  172.         Pstudent p = new Pstudent();
  173.         p.setName("李四");
  174.         p.setAge(20);
  175.         System.out.println(p.getName()+","+p.getAge());
  176.         p.xue();
  177.         p.each();
  178.         p.speakEnglish();
  179.         System.out.println("----------------------------");
  181.         Pteacher p2 = new Pteacher();
  182.         p2.setAge(30);
  183.         p2.setName("曹大大");
  184.         System.out.println(p2.getName()+","+p2.getAge());
  185.         p2.jiao();
  186.         p2.each();
  187.         p2.speakEnglish();
  189.     }
  190. }

7. 内部类

1. 类名作为形参和返回值

image.png

2. 抽象类名作为形参和返回值

image.png

3. 接口名作为形参和返回值

image.png

4. 内部类访问特点

  • 内部类可以直接访问外部类的成员，包括私有
  • 外部类想要访问内部类的成员，必须先创建对象

    5. 成员内部类

    image.png ```java //——————————————————————————————————————主类 package com;

public class Outer { int num = 20; / 第一种 public class Inner{ public void show () { System.out.println(num); } } /

  1. private class Inner{
  2.     public void show() {
  3.         System.out.println(num);
  4.     }
  5. }
  7. public void method() {
  8.     Inner i = new Inner();
  9.     i.show();
  10. }

} //——————————————————————————————————————测试类 package com;

public class Demo { / 第一种 public static void main(String[] args) { Outer.Inner i = new Outer().new Inner(); i.show(); } / public static void main(String[] args) { Outer out = new Outer(); out.method(); } }

  1. <a name="VVN0k"></a>
  2. #### 6. 局部内部类
  3. ![image.png](https://cdn.nlark.com/yuque/0/2021/png/5358492/1618405405099-c58cb979-6905-4ed9-8850-f87777deb3d4.png#align=left&display=inline&height=62&id=VFJv4&margin=%5Bobject%20Object%5D&name=image.png&originHeight=62&originWidth=736&size=48382&status=done&style=none&width=736)
  4. ```java
  5. //----------------------------------------------------------------------------主类
  6. package com;
  8. public class Outer {
  9.     private int num = 10;
  11.     public void method(){
  12.         int a = 30;
  13.         class Inner{
  14.             public void show(){
  15.                 System.out.println(num);
  16.                 System.out.println(a);
  17.             }
  18.         }
  19.         Inner i = new Inner();
  20.         i.show();
  21.     }
  22. }
  23. //----------------------------------------------------------------------------测试类
  24. package com;
  26. public class Demo {
  27.     public static void main(String[] args) {
  28.         Outer o = new Outer();
  29.         o.method();
  30.     }
  31. }

7. 匿名内部类

image.png

  1. //----------------------------------------------------------------------------主类
  2. package com;
  4. public class Outer {
  5.     public void method() {
  6.         inter i = new inter(){
  7.             @Override
  8.             public void show() {
  9.                 System.out.println("内部接口调用");
  10.             }
  11.         };
  12.         for (int a=0;a<5;a++){
  13.             i.show();
  14.         }
  16.     }
  17. }
  18. //----------------------------------------------------------------------------接口类
  19. package com;
  21. public interface inter {
  22.     void show();
  23. }
  24. //----------------------------------------------------------------------------测试类
  25. package com;
  27. public class Demo {
  28.     public static void main(String[] args) {
  29.         Outer o = new Outer();
  30.         o.method();
  31.     }
  32. }

8. 匿名内部类在开发中的使用

image.png

  1. //----------------------------------------------------------------------------主类
  2. package com;
  4. public class Outer {
  5.     public void Method(inter j){
  6.         j.jump();
  7.     }
  8. }
  9. //----------------------------------------------------------------------------接口
  10. package com;
  12. public interface inter {
  13.     void jump();
  14. }
  15. //----------------------------------------------------------------------------测试类
  16. package com;
  18. import java.lang.reflect.Method;
  20. public class Demo {
  21.     public static void main(String[] args) {
  23.         Outer o = new Outer();
  24.         o.Method(new inter(){
  25.             @Override
  26.             public void jump() {
  27.                 System.out.println("猫可以跳高了");
  28.             }
  29.         });
  30.     }
  31. }