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2010-05-31T18:01:45Z

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== Visitor Pattern 1 ==



<source lang="java">
//[C] 2002 Sun Microsystems, Inc.---
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Iterator;
public class RunVisitorPattern {
public static void main(String[] arguments) {
System.out.println("Example for the Visitor pattern");
System.out.println();
System.out
.println("This sample will use a ProjectCostVisitor to calculate");
System.out.println(" the total amount required to complete a Project.");
System.out.println();
System.out.println("Deserializing a test Project for Visitor pattern");
System.out.println();
if (!(new File("data.ser").exists())) {
DataCreator.serialize("data.ser");
}
Project project = (Project) (DataRetriever.deserializeData("data.ser"));
System.out
.println("Creating a ProjectCostVisitor, to calculate the total cost of the project.");
ProjectCostVisitor visitor = new ProjectCostVisitor();
visitor.setHourlyRate(100);
System.out
.println("Moving throuhg the Project, calculating total cost");
System.out
.println(" by passing the Visitor to each of the ProjectItems.");
visitProjectItems(project, visitor);
System.out.println("The total cost for the project is: "
+ visitor.getTotalCost());
}
private static void visitProjectItems(ProjectItem item,
ProjectVisitor visitor) {
item.accept(visitor);
if (item.getProjectItems() != null) {
Iterator subElements = item.getProjectItems().iterator();
while (subElements.hasNext()) {
visitProjectItems((ProjectItem) subElements.next(), visitor);
}
}
}
}
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 Task implements ProjectItem {
private String name;
private ArrayList projectItems = new ArrayList();
private Contact owner;
private double timeRequired;
public Task() {
}
public Task(String newName, Contact newOwner, double newTimeRequired) {
name = newName;
owner = newOwner;
timeRequired = newTimeRequired;
}
public String getName() {
return name;
}
public ArrayList getProjectItems() {
return projectItems;
}
public Contact getOwner() {
return owner;
}
public double getTimeRequired() {
return timeRequired;
}
public void setName(String newName) {
name = newName;
}
public void setOwner(Contact newOwner) {
owner = newOwner;
}
public void setTimeRequired(double newTimeRequired) {
timeRequired = newTimeRequired;
}
public void addProjectItem(ProjectItem element) {
if (!projectItems.contains(element)) {
projectItems.add(element);
}
}
public void removeProjectItem(ProjectItem element) {
projectItems.remove(element);
}
public void accept(ProjectVisitor v) {
v.visitTask(this);
}
}
class Deliverable implements ProjectItem {
private String name;
private String description;
private Contact owner;
private double materialsCost;
private double productionCost;
public Deliverable() {
}
public Deliverable(String newName, String newDescription, Contact newOwner,
double newMaterialsCost, double newProductionCost) {
name = newName;
description = newDescription;
owner = newOwner;
materialsCost = newMaterialsCost;
productionCost = newProductionCost;
}
public String getName() {
return name;
}
public String getDescription() {
return description;
}
public Contact getOwner() {
return owner;
}
public double getMaterialsCost() {
return materialsCost;
}
public double getProductionCost() {
return productionCost;
}
public void setMaterialsCost(double newCost) {
materialsCost = newCost;
}
public void setProductionCost(double newCost) {
productionCost = newCost;
}
public void setName(String newName) {
name = newName;
}
public void setDescription(String newDescription) {
description = newDescription;
}
public void setOwner(Contact newOwner) {
owner = newOwner;
}
public void accept(ProjectVisitor v) {
v.visitDeliverable(this);
}
public ArrayList getProjectItems() {
return null;
}
}
interface ProjectVisitor {
public void visitDependentTask(DependentTask p);
public void visitDeliverable(Deliverable p);
public void visitTask(Task p);
public void visitProject(Project p);
}
interface ProjectItem extends Serializable {
public void accept(ProjectVisitor v);
public ArrayList getProjectItems();
}
class ContactImpl implements Contact {
private String firstName;
private String lastName;
private String title;
private String organization;
public ContactImpl() {
}
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;
}
}
class DataCreator {
private static final String DEFAULT_FILE = "data.ser";
public static void main(String[] args) {
String fileName;
if (args.length == 1) {
fileName = args[0];
} else {
fileName = DEFAULT_FILE;
}
serialize(fileName);
}
public static void serialize(String fileName) {
try {
serializeToFile(createData(), fileName);
} catch (IOException exc) {
exc.printStackTrace();
}
}
private static Serializable createData() {
Contact contact = new ContactImpl("Test", "Subject", "Volunteer",
"United Patterns Consortium");
Project project = new Project("Project 1", "Test Project");
Task task1 = new Task("Task 1", contact, 1);
Task task2 = new Task("Task 2", contact, 1);
project.addProjectItem(new Deliverable("Deliverable 1",
"Layer 1 deliverable", contact, 50.0, 50.0));
project.addProjectItem(task1);
project.addProjectItem(task2);
project.addProjectItem(new DependentTask("Dependent Task 1", contact,
1, 1));
Task task3 = new Task("Task 3", contact, 1);
Task task4 = new Task("Task 4", contact, 1);
Task task5 = new Task("Task 5", contact, 1);
Task task6 = new Task("Task 6", contact, 1);
DependentTask dtask2 = new DependentTask("Dependent Task 2", contact,
1, 1);
task1.addProjectItem(task3);
task1.addProjectItem(task4);
task1.addProjectItem(task5);
task1.addProjectItem(dtask2);
dtask2.addDependentTask(task5);
dtask2.addDependentTask(task6);
dtask2.addProjectItem(new Deliverable("Deliverable 2",
"Layer 3 deliverable", contact, 50.0, 50.0));
task3.addProjectItem(new Deliverable("Deliverable 3",
"Layer 3 deliverable", contact, 50.0, 50.0));
task4.addProjectItem(new Task("Task 7", contact, 1));
task4.addProjectItem(new Deliverable("Deliverable 4",
"Layer 3 deliverable", contact, 50.0, 50.0));
return project;
}
private static void serializeToFile(Serializable content, String fileName)
throws IOException {
ObjectOutputStream serOut = new ObjectOutputStream(
new FileOutputStream(fileName));
serOut.writeObject(content);
serOut.close();
}
}
class DataRetriever {
public static Object deserializeData(String fileName) {
Object returnValue = null;
try {
File inputFile = new File(fileName);
if (inputFile.exists() && inputFile.isFile()) {
ObjectInputStream readIn = new ObjectInputStream(
new FileInputStream(fileName));
returnValue = readIn.readObject();
readIn.close();
} else {
System.err.println("Unable to locate the file " + fileName);
}
} catch (ClassNotFoundException exc) {
exc.printStackTrace();
} catch (IOException exc) {
exc.printStackTrace();
}
return returnValue;
}
}
class DependentTask extends Task {
private ArrayList dependentTasks = new ArrayList();
private double dependencyWeightingFactor;
public DependentTask() {
}
public DependentTask(String newName, Contact newOwner,
double newTimeRequired, double newWeightingFactor) {
super(newName, newOwner, newTimeRequired);
dependencyWeightingFactor = newWeightingFactor;
}
public ArrayList getDependentTasks() {
return dependentTasks;
}
public double getDependencyWeightingFactor() {
return dependencyWeightingFactor;
}
public void setDependencyWeightingFactor(double newFactor) {
dependencyWeightingFactor = newFactor;
}
public void addDependentTask(Task element) {
if (!dependentTasks.contains(element)) {
dependentTasks.add(element);
}
}
public void removeDependentTask(Task element) {
dependentTasks.remove(element);
}
public void accept(ProjectVisitor v) {
v.visitDependentTask(this);
}
}
class Project implements ProjectItem {
private String name;
private String description;
private ArrayList projectItems = new ArrayList();
public Project() {
}
public Project(String newName, String newDescription) {
name = newName;
description = newDescription;
}
public String getName() {
return name;
}
public String getDescription() {
return description;
}
public ArrayList getProjectItems() {
return projectItems;
}
public void setName(String newName) {
name = newName;
}
public void setDescription(String newDescription) {
description = newDescription;
}
public void addProjectItem(ProjectItem element) {
if (!projectItems.contains(element)) {
projectItems.add(element);
}
}
public void removeProjectItem(ProjectItem element) {
projectItems.remove(element);
}
public void accept(ProjectVisitor v) {
v.visitProject(this);
}
}
class ProjectCostVisitor implements ProjectVisitor {
private double totalCost;
private double hourlyRate;
public double getHourlyRate() {
return hourlyRate;
}
public double getTotalCost() {
return totalCost;
}
public void setHourlyRate(double rate) {
hourlyRate = rate;
}
public void resetTotalCost() {
totalCost = 0.0;
}
public void visitDependentTask(DependentTask p) {
double taskCost = p.getTimeRequired() * hourlyRate;
taskCost *= p.getDependencyWeightingFactor();
totalCost += taskCost;
}
public void visitDeliverable(Deliverable p) {
totalCost += p.getMaterialsCost() + p.getProductionCost();
}
public void visitTask(Task p) {
totalCost += p.getTimeRequired() * hourlyRate;
}
public void visitProject(Project p) {
}
}

</source>



== Visitor 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.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.Vector;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import com.sun.java.swing.plaf.windows.WindowsLookAndFeel;
public class OrderManager extends JFrame {
public static final String newline = "\n";
public static final String GET_TOTAL = "Get Total";
public static final String CREATE_ORDER = "Create Order";
public static final String EXIT = "Exit";
public static final String CA_ORDER = "California Order";
public static final String NON_CA_ORDER = "Non-California Order";
public static final String OVERSEAS_ORDER = "Overseas Order";
private JComboBox cmbOrderType;
private JTextField txtOrderAmount, txtAdditionalTax, txtAdditionalSH;
private JLabel lblOrderType, lblOrderAmount;
private JLabel lblAdditionalTax, lblAdditionalSH;
private JLabel lblTotal, lblTotalValue;
private OrderVisitor objVisitor;
public OrderManager() {
super("Visitor Pattern - Example");
//Create the visitor instance
objVisitor = new OrderVisitor();
cmbOrderType = new JComboBox();
cmbOrderType.addItem(OrderManager.CA_ORDER);
cmbOrderType.addItem(OrderManager.NON_CA_ORDER);
cmbOrderType.addItem(OrderManager.OVERSEAS_ORDER);
txtOrderAmount = new JTextField(10);
txtAdditionalTax = new JTextField(10);
txtAdditionalSH = new JTextField(10);
lblOrderType = new JLabel("Order Type:");
lblOrderAmount = new JLabel("Order Amount:");
lblAdditionalTax = new JLabel("Additional Tax(CA Orders Only):");
lblAdditionalSH = new JLabel("Additional S & H(Overseas Orders Only):");
lblTotal = new JLabel("Result:");
lblTotalValue = new JLabel("Click Create or GetTotal Button");
//Create the open button
JButton getTotalButton = new JButton(OrderManager.GET_TOTAL);
getTotalButton.setMnemonic(KeyEvent.VK_G);
JButton createOrderButton = new JButton(OrderManager.CREATE_ORDER);
getTotalButton.setMnemonic(KeyEvent.VK_C);
JButton exitButton = new JButton(OrderManager.EXIT);
exitButton.setMnemonic(KeyEvent.VK_X);
ButtonHandler objButtonHandler = new ButtonHandler(this);
getTotalButton.addActionListener(objButtonHandler);
createOrderButton.addActionListener(objButtonHandler);
exitButton.addActionListener(new ButtonHandler());
//For layout purposes, put the buttons in a separate panel
JPanel buttonPanel = new JPanel();
JPanel panel = new JPanel();
GridBagLayout gridbag2 = new GridBagLayout();
panel.setLayout(gridbag2);
GridBagConstraints gbc2 = new GridBagConstraints();
panel.add(getTotalButton);
panel.add(createOrderButton);
panel.add(exitButton);
gbc2.anchor = GridBagConstraints.EAST;
gbc2.gridx = 0;
gbc2.gridy = 0;
gridbag2.setConstraints(createOrderButton, gbc2);
gbc2.gridx = 1;
gbc2.gridy = 0;
gridbag2.setConstraints(getTotalButton, gbc2);
gbc2.gridx = 2;
gbc2.gridy = 0;
gridbag2.setConstraints(exitButton, gbc2);
//****************************************************
GridBagLayout gridbag = new GridBagLayout();
buttonPanel.setLayout(gridbag);
GridBagConstraints gbc = new GridBagConstraints();
buttonPanel.add(lblOrderType);
buttonPanel.add(cmbOrderType);
buttonPanel.add(lblOrderAmount);
buttonPanel.add(txtOrderAmount);
buttonPanel.add(lblAdditionalTax);
buttonPanel.add(txtAdditionalTax);
buttonPanel.add(lblAdditionalSH);
buttonPanel.add(txtAdditionalSH);
buttonPanel.add(lblTotal);
buttonPanel.add(lblTotalValue);
gbc.insets.top = 5;
gbc.insets.bottom = 5;
gbc.insets.left = 5;
gbc.insets.right = 5;
gbc.anchor = GridBagConstraints.EAST;
gbc.gridx = 0;
gbc.gridy = 0;
gridbag.setConstraints(lblOrderType, gbc);
gbc.anchor = GridBagConstraints.WEST;
gbc.gridx = 1;
gbc.gridy = 0;
gridbag.setConstraints(cmbOrderType, gbc);
gbc.anchor = GridBagConstraints.EAST;
gbc.gridx = 0;
gbc.gridy = 1;
gridbag.setConstraints(lblOrderAmount, gbc);
gbc.anchor = GridBagConstraints.WEST;
gbc.gridx = 1;
gbc.gridy = 1;
gridbag.setConstraints(txtOrderAmount, gbc);
gbc.anchor = GridBagConstraints.EAST;
gbc.gridx = 0;
gbc.gridy = 2;
gridbag.setConstraints(lblAdditionalTax, gbc);
gbc.anchor = GridBagConstraints.WEST;
gbc.gridx = 1;
gbc.gridy = 2;
gridbag.setConstraints(txtAdditionalTax, gbc);
gbc.anchor = GridBagConstraints.EAST;
gbc.gridx = 0;
gbc.gridy = 3;
gridbag.setConstraints(lblAdditionalSH, gbc);
gbc.anchor = GridBagConstraints.WEST;
gbc.gridx = 1;
gbc.gridy = 3;
gridbag.setConstraints(txtAdditionalSH, gbc);
gbc.anchor = GridBagConstraints.EAST;
gbc.gridx = 0;
gbc.gridy = 4;
gridbag.setConstraints(lblTotal, gbc);
gbc.anchor = GridBagConstraints.WEST;
gbc.gridx = 1;
gbc.gridy = 4;
gridbag.setConstraints(lblTotalValue, gbc);
gbc.insets.left = 2;
gbc.insets.right = 2;
gbc.insets.top = 40;
//****************************************************
//Add the buttons and the log to the frame
Container contentPane = getContentPane();
contentPane.add(buttonPanel, BorderLayout.NORTH);
contentPane.add(panel, BorderLayout.CENTER);
try {
UIManager.setLookAndFeel(new WindowsLookAndFeel());
SwingUtilities.updateComponentTreeUI(OrderManager.this);
} catch (Exception ex) {
System.out.println(ex);
}
}
public static void main(String[] args) {
JFrame frame = new OrderManager();
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
//frame.pack();
frame.setSize(500, 400);
frame.setVisible(true);
}
public void setTotalValue(String msg) {
lblTotalValue.setText(msg);
}
public OrderVisitor getOrderVisitor() {
return objVisitor;
}
public String getOrderType() {
return (String) cmbOrderType.getSelectedItem();
}
public String getOrderAmount() {
return txtOrderAmount.getText();
}
public String getTax() {
return txtAdditionalTax.getText();
}
public String getSH() {
return txtAdditionalSH.getText();
}
} // End of class OrderManager
class ButtonHandler implements ActionListener {
OrderManager objOrderManager;
public void actionPerformed(ActionEvent e) {
String totalResult = null;
if (e.getActionCommand().equals(OrderManager.EXIT)) {
System.exit(1);
}
if (e.getActionCommand().equals(OrderManager.CREATE_ORDER)) {
//get input values
String orderType = objOrderManager.getOrderType();
String strOrderAmount = objOrderManager.getOrderAmount();
String strTax = objOrderManager.getTax();
String strSH = objOrderManager.getSH();
double dblOrderAmount = 0.0;
double dblTax = 0.0;
double dblSH = 0.0;
if (strOrderAmount.trim().length() == 0) {
strOrderAmount = "0.0";
}
if (strTax.trim().length() == 0) {
strTax = "0.0";
}
if (strSH.trim().length() == 0) {
strSH = "0.0";
}
dblOrderAmount = new Double(strOrderAmount).doubleValue();
dblTax = new Double(strTax).doubleValue();
dblSH = new Double(strSH).doubleValue();
//Create the order
Order order = createOrder(orderType, dblOrderAmount, dblTax, dblSH);
//Get the Visitor
OrderVisitor visitor = objOrderManager.getOrderVisitor();
// accept the visitor instance
order.accept(visitor);
objOrderManager.setTotalValue(" Order Created Successfully");
}
if (e.getActionCommand().equals(OrderManager.GET_TOTAL)) {
//Get the Visitor
OrderVisitor visitor = objOrderManager.getOrderVisitor();
totalResult = new Double(visitor.getOrderTotal()).toString();
totalResult = " Orders Total = " + totalResult;
objOrderManager.setTotalValue(totalResult);
}
}
public Order createOrder(String orderType, double orderAmount, double tax,
double SH) {
if (orderType.equalsIgnoreCase(OrderManager.CA_ORDER)) {
return new CaliforniaOrder(orderAmount, tax);
}
if (orderType.equalsIgnoreCase(OrderManager.NON_CA_ORDER)) {
return new NonCaliforniaOrder(orderAmount);
}
if (orderType.equalsIgnoreCase(OrderManager.OVERSEAS_ORDER)) {
return new OverseasOrder(orderAmount, SH);
}
return null;
}
public ButtonHandler() {
}
public ButtonHandler(OrderManager inObjOrderManager) {
objOrderManager = inObjOrderManager;
}
} // End of class ButtonHandler
class NonCaliforniaOrder implements Order {
private double orderAmount;
public NonCaliforniaOrder() {
}
public NonCaliforniaOrder(double inp_orderAmount) {
orderAmount = inp_orderAmount;
}
public double getOrderAmount() {
return orderAmount;
}
public void accept(OrderVisitor v) {
v.visit(this);
}
}
class CaliforniaOrder implements Order {
private double orderAmount;
private double additionalTax;
public CaliforniaOrder() {
}
public CaliforniaOrder(double inp_orderAmount, double inp_additionalTax) {
orderAmount = inp_orderAmount;
additionalTax = inp_additionalTax;
}
public double getOrderAmount() {
return orderAmount;
}
public double getAdditionalTax() {
return additionalTax;
}
public void accept(OrderVisitor v) {
v.visit(this);
}
}
interface VisitorInterface {
public void visit(NonCaliforniaOrder nco);
public void visit(CaliforniaOrder co);
public void visit(OverseasOrder oo);
}
class OverseasOrder implements Order {
private double orderAmount;
private double additionalSH;
public OverseasOrder() {
}
public OverseasOrder(double inp_orderAmount, double inp_additionalSH) {
orderAmount = inp_orderAmount;
additionalSH = inp_additionalSH;
}
public double getOrderAmount() {
return orderAmount;
}
public double getAdditionalSH() {
return additionalSH;
}
public void accept(OrderVisitor v) {
v.visit(this);
}
}
class OrderVisitor implements VisitorInterface {
private Vector orderObjList;
private double orderTotal;
public OrderVisitor() {
orderObjList = new Vector();
}
public void visit(NonCaliforniaOrder inp_order) {
orderTotal = orderTotal + inp_order.getOrderAmount();
}
public void visit(CaliforniaOrder inp_order) {
orderTotal = orderTotal + inp_order.getOrderAmount()
+ inp_order.getAdditionalTax();
}
public void visit(OverseasOrder inp_order) {
orderTotal = orderTotal + inp_order.getOrderAmount()
+ inp_order.getAdditionalSH();
}
public double getOrderTotal() {
return orderTotal;
}
}
interface Order {
public void accept(OrderVisitor v);
}

</source>



== Visitor pattern in Java ==



<source lang="java">
/*
The Design Patterns Java Companion
Copyright (C) 1998, by James W. Cooper
IBM Thomas J. Watson Research Center
*/
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.Vector;
import javax.swing.AbstractListModel;
import javax.swing.Box;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
public class VacationDisplay extends JFrame implements ActionListener {
JawtList empList;
JTextField total, btotal;
JButton Vac;
Employee[] employees;
public VacationDisplay() {
super("Vacation Display");
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
JPanel jp = new JPanel();
getContentPane().add(jp);
jp.setLayout(new GridLayout(1, 2));
empList = new JawtList(10);
jp.add(empList);
createEmployees();
Box box = Box.createVerticalBox();
jp.add(box);
total = new JTextField(5);
total.setHorizontalAlignment(JTextField.CENTER);
box.add(total);
box.add(Box.createVerticalStrut(10));
btotal = new JTextField(5);
btotal.setHorizontalAlignment(JTextField.CENTER);
box.add(btotal);
box.add(Box.createVerticalStrut(10));
Vac = new JButton("Vacations");
box.add(Vac);
Vac.addActionListener(this);
setSize(300, 200);
setVisible(true);
total.setText(" ");
total.setBackground(Color.white);
}
public void createEmployees() {
employees = new Employee[7];
int i = 0;
employees[i++] = new Employee("Susan Bear", 55000, 12, 1);
employees[i++] = new Employee("Adam Gehr", 150000, 9, 0);
employees[i++] = new Employee("Fred Harris", 50000, 15, 2);
employees[i++] = new Employee("David Oakley", 57000, 12, 2);
employees[i++] = new Employee("Larry Thomas", 100000, 20, 6);
Boss b = new Boss("Leslie Susi", 175000, 16, 4);
b.setBonusDays(12);
Boss b1 = new Boss("Laurence Byerly", 35000, 17, 6);
b1.setBonusDays(17);
employees[i++] = b;
employees[i++] = b1;
for (i = 0; i < employees.length; i++) {
empList.add(employees[i].getName());
}
}
public void actionPerformed(ActionEvent e) {
VacationVisitor vac = new VacationVisitor();
bVacationVisitor bvac = new bVacationVisitor();
for (int i = 0; i < employees.length; i++) {
employees[i].accept(vac);
employees[i].accept(bvac);
}
total.setText(new Integer(vac.getTotalDays()).toString());
btotal.setText(new Integer(bvac.getTotalDays()).toString());
}
public static void main(String argv[]) {
new VacationDisplay();
}
}
class Employee {
int sickDays, vacDays;
float Salary;
String Name;
public Employee(String name, float salary, int vacdays, int sickdays) {
vacDays = vacdays;
sickDays = sickdays;
Salary = salary;
Name = name;
}
public String getName() {
return Name;
}
public int getSickdays() {
return sickDays;
}
public int getVacDays() {
return vacDays;
}
public float getSalary() {
return Salary;
}
public void accept(Visitor v) {
v.visit(this);
}
}
abstract class Visitor {
public abstract void visit(Employee emp);
public abstract void visit(Boss emp);
}
class Boss extends Employee {
private int bonusDays;
public Boss(String name, float salary, int vacdays, int sickdays) {
super(name, salary, vacdays, sickdays);
}
public void setBonusDays(int bonus) {
bonusDays = bonus;
}
public int getBonusDays() {
return bonusDays;
}
public void accept(Visitor v) {
v.visit(this);
}
}
class VacationVisitor extends Visitor {
protected int total_days;
public VacationVisitor() {
total_days = 0;
}
public void visit(Employee emp) {
total_days += emp.getVacDays();
}
public void visit(Boss boss) {
total_days += boss.getVacDays();
}
public int getTotalDays() {
return total_days;
}
}
class bVacationVisitor extends Visitor {
int total_days;
public bVacationVisitor() {
total_days = 0;
}
public int getTotalDays() {
return total_days;
}
public void visit(Boss boss) {
total_days += boss.getVacDays();
total_days += boss.getBonusDays();
}
public void visit(Employee emp) {
total_days += emp.getVacDays();
}
}
//this is a simple adapter class to
//convert List awt methods to Swing methods
class JawtList extends JScrollPane implements ListSelectionListener, awtList {
private JList listWindow;
private JListData listContents;
public JawtList(int rows) {
listContents = new JListData();
listWindow = new JList(listContents);
listWindow.setPrototypeCellValue("Abcdefg Hijkmnop");
getViewport().add(listWindow);
}
public void add(String s) {
listContents.addElement(s);
}
public void remove(String s) {
listContents.removeElement(s);
}
public void clear() {
listContents.clear();
}
public String[] getSelectedItems() {
Object[] obj = listWindow.getSelectedValues();
String[] s = new String[obj.length];
for (int i = 0; i < obj.length; i++)
s[i] = obj[i].toString();
return s;
}
public void valueChanged(ListSelectionEvent e) {
}
}
class JListData extends AbstractListModel {
private Vector data;
public JListData() {
data = new Vector();
}
public int getSize() {
return data.size();
}
public Object getElementAt(int index) {
return data.elementAt(index);
}
public void addElement(String s) {
data.addElement(s);
fireIntervalAdded(this, data.size() - 1, data.size());
}
public void removeElement(String s) {
data.removeElement(s);
fireIntervalRemoved(this, 0, data.size());
}
public void clear() {
int size = data.size();
data = new Vector();
fireIntervalRemoved(this, 0, size);
}
}
interface awtList {
public void add(String s);
public void remove(String s);
public String[] getSelectedItems();
}

</source>

Java/Design Pattern/Visitor Pattern - История изменений

Admin: 1 версия

в 18:01, 31 мая 2010

← Предыдущая	Версия 06:50, 1 июня 2010
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