要求：分別輸出6、5、4

public class test{
	public static void  main(String [] args) {
		Father.Son son = new Father().new Son();
		son.a();
	}
}
class Father{
	int a=4;
	class Son{
		int a =5;
		public void a() {
			int a = 6;
		System.out.println(?); //1
		System.out.println(?); //2
		System.out.println(?); //3
		}
	}
}
 

1、a

2、this.a

3、new Father().a   通過匿名物件呼叫a

 或  Father.this.a     通過外部名限定this物件，Father.this 代表Father的this  即Father的物件

注意！外部類和內部類沒有繼承關係