sample5_10.java

封装

class Fruit
{ }
//类Apple是Fruit的子类
class Apple extends Fruit
{ }
//类Pear是Fruit的子类
class Pear extends Fruit
{ }
public class Sample5_10
{               public static void main(String[] args)
	{               Apple a=new Apple();
		Fruit f=a;
		Pear p=new Pear();
		//比较Fruit与Apple型引用
		if(a==f)
		{System.out.println("引用a与引用f相等！！！");}
		//比较Apple与Pear型引用
		if(a==p)
		{System.out.println("引用a与引用p相等！！！");}		
	}
}