Java Tutorial/Design Pattern/Iterator Pattern

Iterator pattern for container

   <source lang="java">

import java.util.ArrayList; import java.util.Iterator; public class TestCorporation {

 public static void main(String args[]) {
   Corporation corporation = new Corporation();
   Division rnd = new Division("R&D");
   rnd.add(new VP("A", "R&D"));
   rnd.add(new VP("B", "R&D"));
   rnd.add(new VP("C", "R&D"));
   Division sales = new Division("Sales");
   sales.add(new VP("E", "Sales"));
   sales.add(new VP("F", "Sales"));
   sales.add(new VP("G", "Sales"));
   sales.add(new VP("F", "Sales"));
   Division western = new Division("Sales");
   western.add(new VP("W", "Sales"));
   western.add(new VP("Z", "Sales"));
   sales.add(western);
   VP vp = new VP("Cary", "At Large");
   corporation.add(rnd);
   corporation.add(sales);
   corporation.add(vp);
   corporation.print();
 }

} class Corporation extends Corporate {

 private ArrayList<Corporate> corporate = new ArrayList<Corporate>();

 public Corporation() {
 }
 public void add(Corporate c) {
   corporate.add(c);
 }
 public void print() {
   Iterator iterator = corporate.iterator();
   while (iterator.hasNext()) {
     Corporate c = (Corporate) iterator.next();
     c.print();
   }
 }

} abstract class Corporate {

 public String getName() {
   return "";
 }
 public void add(Corporate c) {
 }
 public Iterator iterator() {
   return null;
 }
 public void print() {
 }

} class Division extends Corporate {

 private Corporate[] corporate = new Corporate[100];
 private int number = 0;
 private String name;
 public Division(String n) {
   name = n;
 }
 public String getName() {
   return name;
 }
 public void add(Corporate c) {
   corporate[number++] = c;
 }
 public Iterator iterator() {
   return new DivisionIterator(corporate);
 }
 public void print() {
   Iterator iterator = iterator();
   while (iterator.hasNext()) {
     Corporate c = (Corporate) iterator.next();
     c.print();
   }
 }

} class VP extends Corporate {

 private String name;
 private String division;
 public VP(String n, String d) {
   name = n;
   division = d;
 }
 public String getName() {
   return name;
 }
 public void print() {
   System.out.println("Name: " + name + " Division: " + division);
 }
 public Iterator iterator() {
   return new VPIterator(this);
 }

} class VPIterator implements Iterator {

 private VP vp;
 public VPIterator(VP v) {
   vp = v;
 }
 public VP next() {
   return vp;
 }
 public boolean hasNext() {
   return false;
 }
 public void remove() {
 }

} class DivisionIterator implements Iterator {

 private Corporate[] corporate;
 private int location = 0;
 public DivisionIterator(Corporate[] c) {
   corporate = c;
 }
 public Corporate next() {
   return corporate[location++];
 }
 public boolean hasNext() {
   if (location < corporate.length && corporate[location] != null) {
     return true;
   } else {
     return false;
   }
 }
 public void remove() {
 }

}</source>