内部类

package oop.Demon10;

public class Outer {

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

    public class Inner{
            public void in(){
                    System.out.println("这是内部类的方法");
            }
            //或得外部类的私有属性
            public void getID(){
                    System.out.println(id);
            }
    }
    }

==========================

package oop;

import oop.Demon10.Outer;

public class Application {
public static void main(String[] args) {
//new
Outer outer = new Outer();

    //通过这个外部类来实现内部类
    Outer.Inner inner = outer.new Inner();
    inner.getID();
}

}