Java/Design Pattern/Builder Pattern

Builder Pattern - Example

   <source lang="java">

/* Software Architecture Design Patterns in Java by Partha Kuchana Auerbach Publications

• /

import java.awt.BorderLayout; import java.awt.Container; import java.awt.Font; import java.awt.GridBagConstraints; import java.awt.GridBagLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.util.Calendar; import javax.swing.JButton; import javax.swing.JComboBox; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JTextArea; import javax.swing.JTextField; import javax.swing.SwingUtilities; import javax.swing.UIManager; import com.sun.java.swing.plaf.windows.WindowsLookAndFeel; public class SearchManager extends JFrame {

 public static final String GET_SQL = "Get SQL";
 public static final String EXIT = "Exit";
 public static final String CANDIDATE_SRCH = "Candidate Search";
 public static final String EMPLOYER_SRCH = "Employer Search";
 public static final String BLANK = "";
 private JComboBox cmbSearchType;
 private JPanel pSearchCriteria;
 private JTextArea txtSQL;
 public SearchManager() throws Exception {
   super("Builder Pattern - Example");
   // Create controls
   cmbSearchType = new JComboBox();
   txtSQL = new JTextArea(" The SQL statement will be displayed here.", 5,
       25);
   txtSQL.setFont(new Font("Serif", Font.ITALIC, 12));
   txtSQL.setLineWrap(true);
   txtSQL.setWrapStyleWord(true);
   pSearchCriteria = new JPanel();
   cmbSearchType.addItem(SearchManager.BLANK);
   cmbSearchType.addItem(SearchManager.CANDIDATE_SRCH);
   cmbSearchType.addItem(SearchManager.EMPLOYER_SRCH);
   //Create Labels
   JLabel lblSearchType = new JLabel("Search:");
   JLabel lblWhereClause = new JLabel("SQL:");
   JLabel lblSearchCriteria = new JLabel("Search Criteria:");
   //Create the open button
   JButton btnGetWhereClause = new JButton(SearchManager.GET_SQL);
   btnGetWhereClause.setMnemonic(KeyEvent.VK_G);
   JButton btnExit = new JButton(SearchManager.EXIT);
   btnExit.setMnemonic(KeyEvent.VK_X);
   buttonHandler vf = new buttonHandler(this);
   btnGetWhereClause.addActionListener(vf);
   btnExit.addActionListener(vf);
   cmbSearchType.addActionListener(vf);
   //For layout purposes, put the buttons in a separate panel
   JPanel buttonPanel = new JPanel();
   //****************************************************
   GridBagLayout gridbag = new GridBagLayout();
   buttonPanel.setLayout(gridbag);
   GridBagConstraints gbc = new GridBagConstraints();
   buttonPanel.add(lblSearchType);
   buttonPanel.add(cmbSearchType);
   buttonPanel.add(lblSearchCriteria);
   buttonPanel.add(pSearchCriteria);
   buttonPanel.add(lblWhereClause);
   buttonPanel.add(txtSQL);
   buttonPanel.add(btnGetWhereClause);
   buttonPanel.add(btnExit);
   gbc.insets.top = 5;
   gbc.insets.bottom = 5;
   gbc.insets.left = 5;
   gbc.insets.right = 5;
   gbc.anchor = GridBagConstraints.WEST;
   gbc.gridx = 0;
   gbc.gridy = 0;
   gridbag.setConstraints(lblSearchType, gbc);
   gbc.gridx = 1;
   gbc.gridy = 0;
   gridbag.setConstraints(cmbSearchType, gbc);
   gbc.gridx = 0;
   gbc.gridy = 1;
   gridbag.setConstraints(lblSearchCriteria, gbc);
   gbc.gridx = 1;
   gbc.gridy = 2;
   gridbag.setConstraints(pSearchCriteria, gbc);
   gbc.gridx = 0;
   gbc.gridy = 3;
   gridbag.setConstraints(lblWhereClause, gbc);
   gbc.anchor = GridBagConstraints.WEST;
   gbc.gridwidth = 3;
   gbc.gridheight = 5;
   gbc.gridx = 1;
   gbc.gridy = 3;
   gridbag.setConstraints(txtSQL, gbc);
   gbc.gridwidth = 1;
   gbc.gridheight = 1;
   gbc.anchor = GridBagConstraints.EAST;
   gbc.insets.left = 2;
   gbc.insets.right = 2;
   gbc.insets.top = 40;
   gbc.gridx = 0;
   gbc.gridy = 8;
   gridbag.setConstraints(btnGetWhereClause, gbc);
   gbc.anchor = GridBagConstraints.WEST;
   gbc.gridx = 1;
   gbc.gridy = 8;
   gridbag.setConstraints(btnExit, gbc);
   //****************************************************
   //Add the buttons and the log to the frame
   Container contentPane = getContentPane();
   contentPane.add(buttonPanel, BorderLayout.CENTER);
   try {
     UIManager.setLookAndFeel(new WindowsLookAndFeel());
     SwingUtilities.updateComponentTreeUI(SearchManager.this);
   } catch (Exception ex) {
     System.out.println(ex);
   }
 }
 public void setSQL(String str) {
   txtSQL.setText(str);
 }
 public String getSearchType() {
   return (String) cmbSearchType.getSelectedItem();
 }
 public JComboBox getSearchTypeCtrl() {
   return cmbSearchType;
 }
 public void displayNewUI(JPanel panel) {
   pSearchCriteria.removeAll();
   pSearchCriteria.add(panel);
   pSearchCriteria.validate();
   validate();
 }
 public static void main(String[] args) throws Exception {
   JFrame frame = new SearchManager();
   frame.addWindowListener(new WindowAdapter() {
     public void windowClosing(WindowEvent e) {
       System.exit(0);
     }
   });
   //frame.pack();
   frame.setSize(450, 400);
   frame.setVisible(true);
 }

} class buttonHandler implements ActionListener {

 SearchManager manager;
 UIBuilder builder;
 public void actionPerformed(ActionEvent e) {
   if (e.getActionCommand().equals(SearchManager.EXIT)) {
     System.exit(1);
   }
   if (e.getActionCommand().equals(SearchManager.GET_SQL)) {
     manager.setSQL(builder.getSQL());
   }
   if (e.getSource() == manager.getSearchTypeCtrl()) {
     String selection = manager.getSearchType();
     if (selection.equals("") == false) {
       BuilderFactory factory = new BuilderFactory();
       //create an appropriate builder instance
       builder = factory.getUIBuilder(selection);
       //configure the director with the builder
       UIDirector director = new UIDirector(builder);
       //director invokes different builder
       // methods
       director.build();
       //get the final build object
       JPanel UIObj = builder.getSearchUI();
       manager.displayNewUI(UIObj);
     }
   }
 }
 public buttonHandler() {
 }
 public buttonHandler(SearchManager inManager) {
   manager = inManager;
 }

} class MyUtil {

 public static String handleRecordLength(String str, int len) {
   int i;
   String retStr = "";
   if (str.length() > len) {
     retStr = str.substring(0, len);
   } else {
     i = len - str.length();
     for (int j = 0; j < i; j++) {
       str = str + " ";
     }
     retStr = str;
   }
   return retStr;
 }

} class BuilderFactory {

 public UIBuilder getUIBuilder(String str) {
   UIBuilder builder = null;
   if (str.equals(SearchManager.CANDIDATE_SRCH)) {
     builder = new CandSrchBuilder();
   } else if (str.equals(SearchManager.EMPLOYER_SRCH)) {
     builder = new EmpSrchBuilder();
   }
   return builder;
 }

} abstract class UIBuilder {

 protected JPanel searchUI;
 public abstract void addUIControls();
 public abstract void initialize();
 public abstract String getSQL();
 public JPanel getSearchUI() {
   return searchUI;
 }

} class UIDirector {

 private UIBuilder builder;
 public UIDirector(UIBuilder bldr) {
   builder = bldr;
 }
 public void build() {
   builder.addUIControls();
   builder.initialize();
 }

} class EmpSrchBuilder extends UIBuilder {

 JLabel lblUserName = new JLabel("Name :");
 private JTextField txtUserName = new JTextField(15);
 private JTextField txtCity = new JTextField(15);
 private JTextField txtRenewal = new JTextField(10);
 public void addUIControls() {
   searchUI = new JPanel();
   JLabel lblUserName = new JLabel("Name :");
   JLabel lblCity = new JLabel("City:");
   JLabel lblRenewal = new JLabel("Membership Renewal :");
   GridBagLayout gridbag = new GridBagLayout();
   searchUI.setLayout(gridbag);
   GridBagConstraints gbc = new GridBagConstraints();
   searchUI.add(lblUserName);
   searchUI.add(txtUserName);
   searchUI.add(lblCity);
   searchUI.add(txtCity);
   searchUI.add(lblRenewal);
   searchUI.add(txtRenewal);
   gbc.anchor = GridBagConstraints.WEST;
   gbc.insets.top = 5;
   gbc.insets.bottom = 5;
   gbc.insets.left = 5;
   gbc.insets.right = 5;
   gbc.gridx = 0;
   gbc.gridy = 0;
   gridbag.setConstraints(lblUserName, gbc);
   gbc.gridx = 0;
   gbc.gridy = 1;
   gridbag.setConstraints(lblCity, gbc);
   gbc.gridx = 0;
   gbc.gridy = 2;
   gridbag.setConstraints(lblRenewal, gbc);
   gbc.anchor = GridBagConstraints.WEST;
   gbc.gridx = 1;
   gbc.gridy = 0;
   gridbag.setConstraints(txtUserName, gbc);
   gbc.gridx = 1;
   gbc.gridy = 1;
   gridbag.setConstraints(txtCity, gbc);
   gbc.gridx = 1;
   gbc.gridy = 2;
   gridbag.setConstraints(txtRenewal, gbc);
 }
 public void initialize() {
   Calendar cal = Calendar.getInstance();
   cal.setTime(new java.util.Date());
   txtUserName.setText("Enter UserName Here");
   txtRenewal.setText((cal.get(Calendar.MONTH) + 1) + "/"
       + cal.get(Calendar.DATE) + "/" + cal.get(Calendar.YEAR));
 }
 public String getSQL() {
   return ("Select * from Employer where Username=""
       + txtUserName.getText() + """ + " and City=""
       + txtCity.getText() + "" and DateRenewal=""
       + txtRenewal.getText() + """);
 }

} class CandSrchBuilder extends UIBuilder {

 private JTextField txtUserName = new JTextField(15);
 private JTextField txtSkill = new JTextField(10);
 private JComboBox cmbExperience = new JComboBox();
 public void addUIControls() {
   searchUI = new JPanel();
   JLabel lblUserName = new JLabel("Name :");
   JLabel lblExperienceRange = new JLabel("Experience(min Yrs.):");
   JLabel lblSkill = new JLabel("Skill :");
   cmbExperience.addItem("<5");
   cmbExperience.addItem(">5");
   GridBagLayout gridbag = new GridBagLayout();
   searchUI.setLayout(gridbag);
   GridBagConstraints gbc = new GridBagConstraints();
   gbc.anchor = GridBagConstraints.WEST;
   searchUI.add(lblUserName);
   searchUI.add(txtUserName);
   searchUI.add(lblExperienceRange);
   searchUI.add(cmbExperience);
   searchUI.add(lblSkill);
   searchUI.add(txtSkill);
   gbc.insets.top = 5;
   gbc.insets.bottom = 5;
   gbc.insets.left = 5;
   gbc.insets.right = 5;
   gbc.gridx = 0;
   gbc.gridy = 0;
   gridbag.setConstraints(lblUserName, gbc);
   gbc.gridx = 0;
   gbc.gridy = 1;
   gridbag.setConstraints(lblExperienceRange, gbc);
   gbc.gridx = 0;
   gbc.gridy = 2;
   gridbag.setConstraints(lblSkill, gbc);
   gbc.anchor = GridBagConstraints.WEST;
   gbc.gridx = 1;
   gbc.gridy = 0;
   gridbag.setConstraints(txtUserName, gbc);
   gbc.gridx = 1;
   gbc.gridy = 1;
   gridbag.setConstraints(cmbExperience, gbc);
   gbc.gridx = 1;
   gbc.gridy = 2;
   gridbag.setConstraints(txtSkill, gbc);
 }
 public void initialize() {
   txtUserName.setText("Enter UserName Here");
   txtSkill.setText("Internet Tech");
 }
 public String getSQL() {
   String experience = (String) cmbExperience.getSelectedItem();
   return ("Select * from Candidate where Username=""
       + txtUserName.getText() + "" and Experience " + experience
       + " and Skill="" + txtSkill.getText() + """);
 }

}

      </source>
   
  
 
  

Builder Pattern in Java

   <source lang="java">

//[C] 2002 Sun Microsystems, Inc.--- import java.io.Serializable; import java.util.ArrayList; import java.util.Calendar; import java.util.Date; public class RunBuilderPattern {

   private static Calendar dateCreator = Calendar.getInstance();
   
   public static void main(String [] arguments){
       Appointment appt = null;
       
       System.out.println("Example for the Builder pattern");
       System.out.println();
       System.out.println("This example demonstrates the use of the Builder");
       System.out.println("pattern to create Appointment objects for the PIM.");
       System.out.println();
       
       System.out.println("Creating a Scheduler for the example.");
       Scheduler pimScheduler = new Scheduler();
       
       System.out.println("Creating an AppointmentBuilder for the example.");
       System.out.println();
       AppointmentBuilder apptBuilder = new AppointmentBuilder();
       try{
           System.out.println("Creating a new Appointment with an AppointmentBuilder");
           appt = pimScheduler.createAppointment(
               apptBuilder, createDate(2066, 9, 22, 12, 30),
               null, "Trek convention", new LocationImpl("Fargo, ND"),
               createAttendees(4));
           System.out.println("Successfully created an Appointment.");
           System.out.println("Appointment information:");
           System.out.println(appt);
           System.out.println();
       }
       catch (InformationRequiredException exc){
           printExceptions(exc);
       }
       
       System.out.println("Creating a MeetingBuilder for the example.");
       MeetingBuilder mtgBuilder = new MeetingBuilder();
       try{
           System.out.println("Creating a new Appointment with a MeetingBuilder");
           System.out.println("(notice that the same create arguments will produce");
           System.out.println(" an exception, since the MeetingBuilder enforces a");
           System.out.println(" mandatory end date)");
           appt = pimScheduler.createAppointment(
               mtgBuilder, createDate(2066, 9, 22, 12, 30),
               null, "Trek convention", new LocationImpl("Fargo, ND"),
               createAttendees(4));
           System.out.println("Successfully created an Appointment.");
           System.out.println("Appointment information:");
           System.out.println(appt);
           System.out.println();
       }
       catch (InformationRequiredException exc){
           printExceptions(exc);
       }
       
       System.out.println("Creating a new Appointment with a MeetingBuilder");
       System.out.println("(This time, the MeetingBuilder will provide an end date)");
       try{
           appt = pimScheduler.createAppointment(
               mtgBuilder,
               createDate(2002, 4, 1, 10, 00),
               createDate(2002, 4, 1, 11, 30),
               "OOO Meeting",
               new LocationImpl("Butte, MT"),
               createAttendees(2));
           System.out.println("Successfully created an Appointment.");
           System.out.println("Appointment information:");
           System.out.println(appt);
           System.out.println();
       }
       catch (InformationRequiredException exc){
           printExceptions(exc);
       }
   }
   
   public static Date createDate(int year, int month, int day, int hour, int minute){
       dateCreator.set(year, month, day, hour, minute);
       return dateCreator.getTime();
   }
   
   public static ArrayList createAttendees(int numberToCreate){
       ArrayList group = new ArrayList();
       for (int i = 0; i < numberToCreate; i++){
           group.add(new ContactImpl("John", getLastName(i), "Employee (non-exempt)", "Yoyodyne Corporation"));
       }
       return group;
   }
   
   public static String getLastName(int index){
       String name = "";
       switch (index % 6){
           case 0: name = "Worfin";
               break;
           case 1: name = "Smallberries";
               break;
           case 2: name = "Bigbootee";
               break;
           case 3: name = "Haugland";
               break;
           case 4: name = "Maassen";
               break;
           case 5: name = "Sterling";
               break;
       }
       return name;
   }
   
   public static void printExceptions(InformationRequiredException exc){
       int statusCode = exc.getInformationRequired();
       
       System.out.println("Unable to create Appointment: additional information is required");
       if ((statusCode & InformationRequiredException.START_DATE_REQUIRED) > 0){
           System.out.println("  A start date is required for this appointment to be complete.");
       }
       if ((statusCode & InformationRequiredException.END_DATE_REQUIRED) > 0){
           System.out.println("  An end date is required for this appointment to be complete.");
       }
       if ((statusCode & InformationRequiredException.DESCRIPTION_REQUIRED) > 0){
           System.out.println("  A description is required for this appointment to be complete.");
       }
       if ((statusCode & InformationRequiredException.ATTENDEE_REQUIRED) > 0){
           System.out.println("  At least one attendee is required for this appointment to be complete.");
       }
       if ((statusCode & InformationRequiredException.LOCATION_REQUIRED) > 0){
           System.out.println("  A location is required for this appointment to be complete.");
       }
       System.out.println();
   }

} interface Contact extends Serializable{

   public static final String SPACE = " ";
   public String getFirstName();
   public String getLastName();
   public String getTitle();
   public String getOrganization();
   
   public void setFirstName(String newFirstName);
   public void setLastName(String newLastName);
   public void setTitle(String newTitle);
   public void setOrganization(String newOrganization);

} class ContactImpl implements Contact{

   private String firstName;
   private String lastName;
   private String title;
   private String organization;
   
   public ContactImpl(String newFirstName, String newLastName,
       String newTitle, String newOrganization){
           firstName = newFirstName;
           lastName = newLastName;
           title = newTitle;
           organization = newOrganization;
   }
   
   public String getFirstName(){ return firstName; }
   public String getLastName(){ return lastName; }
   public String getTitle(){ return title; }
   public String getOrganization(){ return organization; }
   
   public void setFirstName(String newFirstName){ firstName = newFirstName; }
   public void setLastName(String newLastName){ lastName = newLastName; }
   public void setTitle(String newTitle){ title = newTitle; }
   public void setOrganization(String newOrganization){ organization = newOrganization; }
   
   public String toString(){
       return firstName + SPACE + lastName;
   }

} interface Location extends Serializable{

   public String getLocation();
   public void setLocation(String newLocation);

} class LocationImpl implements Location{

   private String location;
   
   public LocationImpl(){ }
   public LocationImpl(String newLocation){
       location = newLocation;
   }
   
   public String getLocation(){ return location; }
   
   public void setLocation(String newLocation){ location = newLocation; }
   
   public String toString(){ return location; }

} class Scheduler{

   public Appointment createAppointment(AppointmentBuilder builder,
       Date startDate, Date endDate, String description,
       Location location, ArrayList attendees) throws InformationRequiredException{
           if (builder == null){
               builder = new AppointmentBuilder();
           }
       builder.buildAppointment();
       builder.buildDates(startDate, endDate);
       builder.buildDescription(description);
       builder.buildAttendees(attendees);
       builder.buildLocation(location);
       return builder.getAppointment();
   }

} class Appointment{

   private Date startDate;
   private Date endDate;
   private String description;
   private ArrayList attendees = new ArrayList();
   private Location location;
   public static final String EOL_STRING =
       System.getProperty("line.separator");
   
   public Date getStartDate(){ return startDate; }
   public Date getEndDate(){ return endDate; }
   public String getDescription(){ return description; }
   public ArrayList getAttendees(){ return attendees; }
   public Location getLocation(){ return location; }
   public void setDescription(String newDescription){ description = newDescription; }
   public void setLocation(Location newLocation){ location = newLocation; }
   public void setStartDate(Date newStartDate){ startDate = newStartDate; }
   public void setEndDate(Date newEndDate){ endDate = newEndDate; }
   public void setAttendees(ArrayList newAttendees){
       if (newAttendees != null){
           attendees = newAttendees;
       }
   }
   
   public void addAttendee(Contact attendee){
       if (!attendees.contains(attendee)){
           attendees.add(attendee);
       }
   }
   
   public void removeAttendee(Contact attendee){
       attendees.remove(attendee);
   }
   
   public String toString(){
       return "  Description: " + description + EOL_STRING +
           "  Start Date: " + startDate + EOL_STRING +
           "  End Date: " + endDate + EOL_STRING +
           "  Location: " + location + EOL_STRING +
           "  Attendees: " + attendees;
   }

} class AppointmentBuilder{

   public static final int START_DATE_REQUIRED = 1;
   public static final int END_DATE_REQUIRED = 2;
   public static final int DESCRIPTION_REQUIRED = 4;
   public static final int ATTENDEE_REQUIRED = 8;
   public static final int LOCATION_REQUIRED = 16;
   
   protected Appointment appointment;
   
   protected int requiredElements;
   
   public void buildAppointment(){
       appointment = new Appointment();
   }
   
   public void buildDates(Date startDate, Date endDate){
       Date currentDate = new Date();
       if ((startDate != null) && (startDate.after(currentDate))){
           appointment.setStartDate(startDate);
       }
       if ((endDate != null) && (endDate.after(startDate))){
           appointment.setEndDate(endDate);
       }
   }
   
   public void buildDescription(String newDescription){
       appointment.setDescription(newDescription);
   }
   
   public void buildAttendees(ArrayList attendees){
       if ((attendees != null) && (!attendees.isEmpty())){
           appointment.setAttendees(attendees);
       }
   }
   
   public void buildLocation(Location newLocation){
       if (newLocation != null){
           appointment.setLocation(newLocation);
       }
   }
   
   public Appointment getAppointment() throws InformationRequiredException{
       requiredElements = 0;
       
       if (appointment.getStartDate() == null){
           requiredElements += START_DATE_REQUIRED;
       }
       
       if (appointment.getLocation() == null){
           requiredElements += LOCATION_REQUIRED;
       }
       
       if (appointment.getAttendees().isEmpty()){
           requiredElements += ATTENDEE_REQUIRED;
       }
       
       if (requiredElements > 0){
           throw new InformationRequiredException(requiredElements);
       }
       return appointment;
   }
   
   public int getRequiredElements(){ return requiredElements; }

} class InformationRequiredException extends Exception{

   private static final String MESSAGE = "Appointment cannot be created because further information is required";
   public static final int START_DATE_REQUIRED = 1;
   public static final int END_DATE_REQUIRED = 2;
   public static final int DESCRIPTION_REQUIRED = 4;
   public static final int ATTENDEE_REQUIRED = 8;
   public static final int LOCATION_REQUIRED = 16;
   private int informationRequired;
   
   public InformationRequiredException(int itemsRequired){
       super(MESSAGE);
       informationRequired = itemsRequired;
   }
   
   public int getInformationRequired(){ return informationRequired; }

} class MeetingBuilder extends AppointmentBuilder{

   public Appointment getAppointment() throws InformationRequiredException{
       try{
           super.getAppointment();
       }
       finally{
           if (appointment.getEndDate() == null){
               requiredElements += END_DATE_REQUIRED;
           }
           
           if (requiredElements > 0){
               throw new InformationRequiredException(requiredElements);
           }
       }
       return appointment;
   }

}

      </source>