Mega Code Archive
Visitor pattern in Java
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/*
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();
}
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