面向对象17N种内部类

package com.oop;


import com.oop.demo10.Outer;

public class Application {
    public static void main(String[] args) {
        Outer outer = new Outer();
        //通过外部类来实例化内部类
        Outer.Inner inner = outer.new Inner();
        inner.getID();
    }

package com.oop.demo10;

public class Outer {

    //局部内部类
    public void method(){
        class Inner{
            public void in(){

            }

        }
    }

    private int id=10;
    public void out(){
        System.out.println("这是外部类方法");
    }

    public class Inner{
        public void in(){
            System.out.println("这是内部类方法");
        }

        //获得外部类的私有属性~
        public void getID(){
            System.out.println(id);
        }
    }
}
//一个java文件里可以有多个class类，但只能有一个public class类
class A{

}

}

package com.oop.demo10;

public class Test {
    public static void main(String[] args) {
        //没有名字初始化类,不用将实例保存到变量中
        new Apple().eat();
        UserService userService = new UserService(){

            @Override
            public void hello() {

            }
        };

    }
}

class Apple{
    public void eat(){
        System.out.println("1");
    }
}

interface UserService{
    void hello();

}