home *** CD-ROM | disk | FTP | other *** search
Java Source | 2000-05-25 | 4.5 KB | 126 lines |
- //: PetCount2.java
- //////////////////////////////////////////////////
- // Copyright (c) Bruce Eckel, 1998
- // Source code file from the book "Thinking in Java"
- // All rights reserved EXCEPT as allowed by the
- // following statements: You can freely use this file
- // for your own work (personal or commercial),
- // including modifications and distribution in
- // executable form only. Permission is granted to use
- // this file in classroom situations, including its
- // use in presentation materials, as long as the book
- // "Thinking in Java" is cited as the source.
- // Except in classroom situations, you cannot copy
- // and distribute this code; instead, the sole
- // distribution point is http://www.BruceEckel.com
- // (and official mirror sites) where it is
- // freely available. You cannot remove this
- // copyright and notice. You cannot distribute
- // modified versions of the source code in this
- // package. You cannot use this file in printed
- // media without the express permission of the
- // author. Bruce Eckel makes no representation about
- // the suitability of this software for any purpose.
- // It is provided "as is" without express or implied
- // warranty of any kind, including any implied
- // warranty of merchantability, fitness for a
- // particular purpose or non-infringement. The entire
- // risk as to the quality and performance of the
- // software is with you. Bruce Eckel and the
- // publisher shall not be liable for any damages
- // suffered by you or any third party as a result of
- // using or distributing software. In no event will
- // Bruce Eckel or the publisher be liable for any
- // lost revenue, profit, or data, or for direct,
- // indirect, special, consequential, incidental, or
- // punitive damages, however caused and regardless of
- // the theory of liability, arising out of the use of
- // or inability to use software, even if Bruce Eckel
- // and the publisher have been advised of the
- // possibility of such damages. Should the software
- // prove defective, you assume the cost of all
- // necessary servicing, repair, or correction. If you
- // think you've found an error, please email all
- // modified files with clearly commented changes to:
- // Bruce@EckelObjects.com. (Please use the same
- // address for non-code errors found in the book.)
- /////////////////////////////////////////////////
-
- // Using Java 1.1 class literals
- package c11.petcount2;
- 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 PetCount2 {
- public static void main(String[] args) {
- Vector pets = new Vector();
- Class[] petTypes = {
- // Class literals work in Java 1.1+ only:
- Pet.class,
- Dog.class,
- Pug.class,
- Cat.class,
- Rodent.class,
- Gerbil.class,
- Hamster.class,
- };
- try {
- for(int i = 0; i < 15; i++) {
- // Offset by one to eliminate Pet.class:
- int rnd = 1 + (int)(
- Math.random() * (petTypes.length - 1));
- pets.addElement(
- petTypes[rnd].newInstance());
- }
- } catch(InstantiationException e) {}
- catch(IllegalAccessException e) {}
- Hashtable h = new Hashtable();
- for(int i = 0; i < petTypes.length; i++)
- h.put(petTypes[i].toString(),
- new Counter());
- for(int i = 0; i < pets.size(); i++) {
- Object o = pets.elementAt(i);
- if(o instanceof Pet)
- ((Counter)h.get(
- "class c11.petcount2.Pet")).i++;
- if(o instanceof Dog)
- ((Counter)h.get(
- "class c11.petcount2.Dog")).i++;
- if(o instanceof Pug)
- ((Counter)h.get(
- "class c11.petcount2.Pug")).i++;
- if(o instanceof Cat)
- ((Counter)h.get(
- "class c11.petcount2.Cat")).i++;
- if(o instanceof Rodent)
- ((Counter)h.get(
- "class c11.petcount2.Rodent")).i++;
- if(o instanceof Gerbil)
- ((Counter)h.get(
- "class c11.petcount2.Gerbil")).i++;
- if(o instanceof Hamster)
- ((Counter)h.get(
- "class c11.petcount2.Hamster")).i++;
- }
- for(int i = 0; i < pets.size(); i++)
- System.out.println(
- pets.elementAt(i).getClass().toString());
- Enumeration keys = h.keys();
- while(keys.hasMoreElements()) {
- String nm = (String)keys.nextElement();
- Counter cnt = (Counter)h.get(nm);
- System.out.println(
- nm.substring(nm.lastIndexOf('.') + 1) +
- " quantity: " + cnt.i);
- }
- }
- } ///:~