1 package com.kai.li; 2  3 /** 4   * 5   */ 6 public class FlyText{ 7     public static void main(String[] args){ 8         Plane p = new Plane(); 9         Bird b = new Bird();10         makeFly(p);11         makeFly(b);12         makeFly("dddkkdkdk");13         makeFly(20.5);14         makeFly(new Object());15     }16     public static void makeFly(Object o){17         if(!(o instanceof ICanFly))18             System.out.println("I can‘t fly.");19         else 20             ((ICanFly)o).fly();21     }22 }

1 package com.kai.li;2 /**3   * 4   */5 public interface ICanFly{6     void fly();7 }

 1 package com.kai.li; 2  3 /** 4   * 5   */ 6 public class Plane implements ICanFly{ 7     public void fly(){ 8         System.out.println("I am a plane,I can fly."); 9     }10 }

 1 package com.kai.li; 2  3 /** 4   * 5   */ 6 public class Bird implements ICanFly{ 7     @Override 8     public void fly(){ 9         System.out.println("I am a bird,I can fly.");10     }11 }