題目：

        要求不全main方法以及填寫Demo01中的輸出語句，依次輸出30,20,10

筆記：

        1、內部類和外部類沒有繼承關係

        2、通過外部類限定this.物件

                                                    Demo01.this

public class Test {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
}
}
class Demo01{
public int num=10;
class Demo02{
public int num=20;
public void show(){
int num=30;
System.out.println(?);
System.out.println(??);
System.out.println(???);
}

}

}

-----------------------------------------------------------------------------------------------------------------------------

package com.gem.demo01;

public class Test {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Demo01.Demo02 de=new Demo01().new Demo02();
de.show();
}

}
class Demo01{
public int num=10;
class Demo02{
public int num=20;
public void show(){
int num=30;
System.out.println(num);
System.out.println(this.num);
//System.out.println(new Demo01().num);
System.out.println(Demo01.this.num);
}

}
}