Excercise 9_2

//:c09:Gerbil.java

public class Gerbil{
 private int gerbilNumber;

 Gerbil(int i){
  gerbilNumber=i;
 }

 public void hop(){
  System.out.println("This is Gerbil#"+gerbilNumber+"hopping");
 }
}

//:c09:MyGerbil1.java

import java.util.*;

public class MyGerbil1{
 public static void main(String[] args){
  ArrayList gerbils=new ArrayList();
  for (int i=0;i<3;i++)
   gerbils.add(new Gerbil(i));
  for (int i=0;i<gerbils.size();i++)
   ((Gerbil)gerbils.get(i)).hop();
 }
}