1 public abstract class Person {
2     //唱歌可就不一样了，唱法不同，唱功不同；而且哑巴不能唱歌
3     public void singing(){
4         System.out.println("我要唱歌");
5     }
6
7     //吃饭，大家没什么区别吧
8     public abstract void eating();
9 }

1 public interface Singable {
2      public void sing();
3 }

public class ZhangSan extends Person implements Singable{@Overridepublic void sing() {// TODO Auto-generated method stub
        }}

public class TongSuSinging implements Singable {@Overridepublic void sing() {System.out.println("找不到方向，到彩虹天堂·····");}}

public class MeiShengSinging implements Singable{@Overridepublic void sing() {System.out.println("you and me,together.");}}

public class MinZuSinging implements Singable{@Overridepublic void sing() {System.out.println("五十六个民族，五十六枝花....");}}

public abstract class Person {//使用组合，将Singable作为Person的成员变量private Singable singable;//再增加动态赋值的方法public void setSingable(Singable s){singable = s;}//此时的sing()方法应该这样写public void sing(){singable.sing();//这里就是面向接口编程，可以使用多态
    }//吃饭，大家没什么区别吧public abstract void eating();
}

1 public class LiSi extends Person {
2
3     @Override
4     public void eating() {
5         // TODO Auto-generated method stub
6
7     }
8
9 }

 1 public class Test {
 2
 3     public static void main(String[] args) {
 4         LiSi ls = new LiSi();
 5         //想要美声唱法，那就生成美声唱法的对象，但是类型统一用Singable
 6         Singable s = new MeiShengSinging();
 7         ls.setSingable(s);
 8         ls.sing();
 9
10         //想要通俗唱法，就生成通俗唱法的对象
11         s = new TongSuSinging();//调用的代码完全不变，仅仅是new的对象类型变了而已
12         ls.setSingable(s);
13         ls.sing();
14     }
15
16 }