Java Tutorial/Design Pattern/Builder Pattern

Builder pattern: build a house

   <source lang="java">

import java.util.LinkedList; import java.util.List; public class BuilderDemo {

 public static void main(String[] args) {
   HouseBuilder builder = new SimpleHouseBuilder();
   HouseBuildingCompany houseBuildingCompany = new HouseBuildingCompany();
   House house = houseBuildingCompany.build(builder);
   System.out.println(house);
 }

} interface HouseBuilder {

 void buildBasement();
 void buildWalls();
 void buildRoof();
 House getHouse();

} class HouseBuildingCompany {

 public House build(HouseBuilder builder) {
   builder.buildBasement();
   builder.buildWalls();
   builder.buildRoof();
   return builder.getHouse();
 }

} class SimpleHouseBuilder implements HouseBuilder {

 private House house;
 public SimpleHouseBuilder() {
   this.house = new House();
 }
 public void buildBasement() {
   this.house.setBasement(new Basement());
 }
 public void buildWalls() {
   for (int i = 0; i < 4; i++)
     this.house.addWall(new Wall());
 }
 public void buildRoof() {
   this.house.setRoot(new Roof());
 }
 public House getHouse() {
   return this.house;
 }

} class Basement {

 @Override
 public String toString() {
   return "Basement";
 }

} class Wall {

 @Override
 public String toString() {
   return "Wall";
 }

} class Roof {

 @Override
 public String toString() {
   return "Roof";
 }

} class House {

 private Basement basement;
 private List<Wall> walls;
 private Roof roof;
 public House() {
   this.walls = new LinkedList<Wall>();
 }
 public void addWall(Wall wall) {
   this.walls.add(wall);
 }
 public void setRoot(Roof roof) {
   this.roof = roof;
 }
 public void setBasement(Basement basement) {
   this.basement = basement;
 }
 @Override
 public String toString() {
   return "House {" + this.basement + ", " + this.walls + ", " + this.roof + "}";
 }

}</source>

Builder pattern with interface

   <source lang="java">

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

 public static void main(String args[]) {
   Machine builder;
   RobotBuildable robot;
   String response = "a";
   builder = new Cooker();
   // builder = new AutomotiveRobotBuilder();
   // Start the construction process.
   builder.addStart();
   builder.addTest();
   builder.addAssemble();
   builder.addStop();
   robot = builder.getRobot();
   robot.go();
 }

} interface Machine {

 public void addStart();
 public void addGetParts();
 public void addAssemble();
 public void addTest();
 public void addStop();
 public RobotBuildable getRobot();

} interface RobotBuildable {

 public void go();

} class Cooker implements Machine {

 CookerBuildable robot;
 ArrayList<Integer> actions;
 public Cooker() {
   robot = new CookerBuildable();
   actions = new ArrayList<Integer>();
 }
 public void addStart() {
   actions.add(new Integer(1));
 }
 public void addGetParts() {
   actions.add(new Integer(2));
 }
 public void addAssemble() {
   actions.add(new Integer(3));
 }
 public void addTest() {
   actions.add(new Integer(4));
 }
 public void addStop() {
   actions.add(new Integer(5));
 }
 public RobotBuildable getRobot() {
   robot.loadActions(actions);
   return robot;
 }

} class Car implements Machine {

 CarBuildable robot;
 ArrayList<Integer> actions;
 public Car() {
   robot = new CarBuildable();
   actions = new ArrayList<Integer>();
 }
 public void addStart() {
   actions.add(new Integer(1));
 }
 public void addGetParts() {
   actions.add(new Integer(2));
 }
 public void addAssemble() {
   actions.add(new Integer(3));
 }
 public void addTest() {
   actions.add(new Integer(4));
 }
 public void addStop() {
   actions.add(new Integer(5));
 }
 public RobotBuildable getRobot() {
   robot.loadActions(actions);
   return robot;
 }

} class CookerBuildable implements RobotBuildable {

 ArrayList<Integer> actions;
 public CookerBuildable() {
 }
 public final void go() {
   Iterator itr = actions.iterator();
   while (itr.hasNext()) {
     switch ((Integer) itr.next()) {
     case 1:
       start();
       break;
     case 2:
       getParts();
       break;
     case 3:
       assemble();
       break;
     case 4:
       test();
       break;
     case 5:
       stop();
       break;
     }
   }
 }
 public void start() {
   System.out.println("Starting....");
 }
 public void getParts() {
   System.out.println("Getting flour and sugar....");
 }
 public void assemble() {
   System.out.println("Baking a cookie....");
 }
 public void test() {
   System.out.println("Crunching a cookie....");
 }
 public void stop() {
   System.out.println("Stopping....");
 }
 public void loadActions(ArrayList<Integer> a) {
   actions = a;
 }

} class CarBuildable implements RobotBuildable {

 ArrayList<Integer> actions;
 public CarBuildable() {
 }
 public final void go() {
   Iterator itr = actions.iterator();
   while (itr.hasNext()) {
     switch ((Integer) itr.next()) {
     case 1:
       start();
       break;
     case 2:
       getParts();
       break;
     case 3:
       assemble();
       break;
     case 4:
       test();
       break;
     case 5:
       stop();
       break;
     }
   }
 }
 public void start() {
   System.out.println("Starting....");
 }
 public void getParts() {
   System.out.println("Getting a carburetor....");
 }
 public void assemble() {
   System.out.println("Installing the carburetor....");
 }
 public void test() {
   System.out.println("Revving the engine....");
 }
 public void stop() {
   System.out.println("Stopping....");
 }
 public void loadActions(ArrayList<Integer> a) {
   actions = a;
 }

}</source>

Example of the Builder pattern

   <source lang="java">

import java.util.ArrayList; import java.util.Arrays; import java.util.Iterator; import java.util.List; class Office extends ArrayList<OfficeUnit> { } class Word extends Office { } class PPT extends Office { } class Excel extends Office { } class OfficeUnit {

 private String s;
 public OfficeUnit(String s) {
   this.s = s;
 }
 public String toString() {
   return s;
 }

} class DocumentPage extends OfficeUnit {

 public DocumentPage(String s) {
   super(s);
 }

} class PPTSlide extends OfficeUnit {

 public PPTSlide(String s) {
   super(s);
 }

} class ExcelWorkbook extends OfficeUnit {

 public ExcelWorkbook(String s) {
   super(s);
 }

} class OfficeBuilder {

 public void buildBase() {
 }
 public void addOfficeUnit(OfficeUnit item) {
 }
 public Office getFinishedMedia() {
   return null;
 }

} class WordBuilder extends OfficeBuilder {

 private Word b;
 public void buildBase() {
   System.out.println("Building word framework");
   b = new Word();
 }
 public void addOfficeUnit(OfficeUnit chapter) {
   System.out.println("Adding word page " + chapter);
   b.add(chapter);
 }
 public Office getFinishedMedia() {
   return b;
 }

} class PPTBuilder extends OfficeBuilder {

 private PPT m;
 public void buildBase() {
   System.out.println("Building PPT");
   m = new PPT();
 }
 public void addOfficeUnit(OfficeUnit article) {
   System.out.println("Adding slide" + article);
   m.add(article);
 }
 public Office getFinishedMedia() {
   return m;
 }

} class ExcelBuilder extends OfficeBuilder {

 private Excel w;
 public void buildBase() {
   System.out.println("Building Excel");
   w = new Excel();
 }
 public void addOfficeUnit(OfficeUnit webItem) {
   System.out.println("Adding workbook" + webItem);
   w.add(webItem);
 }
 public Office getFinishedMedia() {
   return w;
 }

} class OfficeDirector {

 private OfficeBuilder mb;
 public OfficeDirector(OfficeBuilder mb) {
   this.mb = mb; 
 }
 public Office produceMedia(List input) {
   mb.buildBase();
   for (Iterator it = input.iterator(); it.hasNext();)
     mb.addOfficeUnit((OfficeUnit) it.next());
   return mb.getFinishedMedia();
 }

}; public class BuildOfficeDemo {

 public static void main(String[] args) {
   List input = Arrays.asList(new OfficeUnit[] { new OfficeUnit("item1"), new OfficeUnit("item2"),
       new OfficeUnit("item3"), new OfficeUnit("item4"), });
   OfficeDirector buildBook = new OfficeDirector(new WordBuilder());
   Office word = buildBook.produceMedia(input);
   String result = "word: " + word;
   System.out.println(result);
   OfficeDirector buildMagazine = new OfficeDirector(new PPTBuilder());
   Office ppt = buildMagazine.produceMedia(input);
   result = "PPT: " + ppt;
   System.out.println(result);
   OfficeDirector buildWebSite = new OfficeDirector(new ExcelBuilder());
   Office excel = buildWebSite.produceMedia(input);
   result = "Excel: " + excel;
   System.out.println(result);
 }

}</source>