写个简单例子人吃饭，体现面向对象编程,包含接口，抽象类的用处。

一、定义一个接口类：Person,再定义三个类实现它，分别是RichMan,PoorMan,CommonMan。
二、定义一个抽象类：Food,再定义三个类继承它，分别是Noodle,Meat,MeatNoodle(肉丝面)。
三、定义一个方法类:EatFood,将Person 和Food进行关联。
四、最后，写个测试类:TestPersonEatFood

 

1、Person

package EatFood;/** * @author 王永涛 2009-12-28 晚上 弥补以前的遗憾！ * */public interface Person{public void eat(Food food);}

 

2、 PoorMan

package EatFood;import java.sql.Date;/** * @author 王永涛 2009-12-28 晚上 * */public class PoorMan implements Person{public void eat(Food food){System.out.println("穷人的食物： "+food.getName()+" "+(new Date(System.currentTimeMillis())));}}

 

3、RichMan

package EatFood;import java.sql.Date;/** * @author 王永涛 2009-12-28 晚上 * */public class RichMan implements Person{public void eat(Food food){System.out.println("富人的食物： "+food.getName()+" "+(new Date(System.currentTimeMillis())));}}

 

4、CommonMan

package EatFood;import java.sql.Date;/** * @author 王永涛 2009-12-28 晚上 * */public class CommonMan implements Person{public void eat(Food food){System.out.println("普通人食物："+food.getName()+" "+(new Date(System.currentTimeMillis())));}}

 

5、Food

package EatFood;/** * @author 王永涛 2009-12-28 晚上 * */public abstract class Food{protected String name;public String getName(){return name;}public void setName(String name){this.name = name;}}

 

6、Noodle

package EatFood;/** * @author 王永涛 2009-12-28 晚上 * */public class Noodle extends Food{public Noodle(String name){this.name=name;}}

 

7、Meat

package EatFood;/** * @author 王永涛 2009-12-28 晚上 * */public class Meat extends Food{public Meat(String name){this.name=name;}}

 

8、MeatNoodle

package EatFood;/** * @author 王永涛 2009-12-28 晚上 * */public class MeatNoodle extends Food{public MeatNoodle(String name){this.name=name;}}

 

9、EatFood

package EatFood;/** * @author 王永涛 2009-12-28 晚上 * */public class EatFood{public void eat(Person person,Food food){person.eat(food);}}

 

10、TestPersonEatFood

package EatFood;/** * @author 王永涛 2009-12-28 晚上 * */public class TestPersonEatFood{/** * @param args */public static void main(String[] args){Person poor=new PoorMan();Person rich=new RichMan();Person common=new CommonMan();Food noodle=new Noodle("面条");Food meat=new Meat("肉丝");Food meatnoodle=new MeatNoodle("肉丝面");EatFood ef=new EatFood();ef.eat(poor, noodle);ef.eat(rich, meat);ef.eat(common, meatnoodle);}}

 

总结：很幼稚，各位大牛，不要见笑，呵呵！