//: c11:petcount:PetCount.java // From Thinking in Java, 2nd Edition // Available at http://www.BruceEckel.com // (c) Bruce Eckel 1999 // Copyright notice in Copyright.txt // Using instanceof package c11.petcount; import java.util.*; class Pet {} class Dog extends Pet {} class Pug extends Dog {} class Cat extends Pet {} class Rodent extends Pet {} class Gerbil extends Rodent {} class Hamster extends Rodent {} class Counter { int i; } public class PetCount { static String[] typenames = { "Pet", "Dog", "Pug", "Cat", "Rodent", "Gerbil", "Hamster", }; public static void main(String[] args) { ArrayList pets = new ArrayList(); try { Class[] petTypes = { Class.forName("c11.petcount.Dog"), Class.forName("c11.petcount.Pug"), Class.forName("c11.petcount.Cat"), Class.forName("c11.petcount.Rodent"), Class.forName("c11.petcount.Gerbil"), Class.forName("c11.petcount.Hamster"), }; for(int i = 0; i < 15; i++) pets.add( petTypes[ (int)(Math.random()*petTypes.length)] .newInstance()); } catch(InstantiationException e) {} catch(IllegalAccessException e) {} catch(ClassNotFoundException e) {} HashMap h = new HashMap(); for(int i = 0; i < typenames.length; i++) h.put(typenames[i], new Counter()); for(int i = 0; i < pets.size(); i++) { Object o = pets.get(i); if(o instanceof Pet) ((Counter)h.get("Pet")).i++; if(o instanceof Dog) ((Counter)h.get("Dog")).i++; if(o instanceof Pug) ((Counter)h.get("Pug")).i++; if(o instanceof Cat) ((Counter)h.get("Cat")).i++; if(o instanceof Rodent) ((Counter)h.get("Rodent")).i++; if(o instanceof Gerbil) ((Counter)h.get("Gerbil")).i++; if(o instanceof Hamster) ((Counter)h.get("Hamster")).i++; } for(int i = 0; i < pets.size(); i++) System.out.println( pets.get(i).getClass().toString()); for(int i = 0; i < typenames.length; i++) System.out.println( typenames[i] + " quantity: " + ((Counter)h.get(typenames[i])).i); } } ///:~