State Pattern in Java : State Pattern « Design Pattern « Java

1. Java
2. Design Pattern
3. State Pattern

State Pattern in Java

//[C] 2002 Sun Microsystems, Inc.---

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
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.Calendar;
import java.util.Date;

import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.AbstractTableModel;

public class RunStatePattern {
  public static void main(String[] arguments) {
    System.out.println("Example for the State pattern");
    System.out.println();

    if (!(new File("appointments.ser").exists())) {
      DataCreator.serialize("appointments.ser");
    }

    System.out.println("Creating CalendarEditor");
    CalendarEditor appointmentBook = new CalendarEditor();
    System.out.println("");

    System.out.println("Created. Appointments:");
    System.out.println(appointmentBook.getAppointments());

    System.out.println("Created. Creating GUI:");
    StateGui application = new StateGui(appointmentBook);
    application.createGui();
    System.out.println("");
  }
}

interface State {
  public void save();

  public void edit();
}

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() {
  }

  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 FileLoader {
  public static Object loadData(File inputFile) {
    Object returnValue = null;
    try {
      if (inputFile.exists()) {
        if (inputFile.isFile()) {
          ObjectInputStream readIn = new ObjectInputStream(
              new FileInputStream(inputFile));
          returnValue = readIn.readObject();
          readIn.close();
        } else {
          System.err.println(inputFile + " is a directory.");
        }
      } else {
        System.err.println("File " + inputFile + " does not exist.");
      }
    } catch (ClassNotFoundException exc) {
      exc.printStackTrace();

    } catch (IOException exc) {
      exc.printStackTrace();

    }
    return returnValue;
  }

  public static void storeData(File outputFile, Serializable data) {
    try {
      ObjectOutputStream writeOut = new ObjectOutputStream(
          new FileOutputStream(outputFile));
      writeOut.writeObject(data);
      writeOut.close();
    } catch (IOException exc) {
      exc.printStackTrace();
    }
  }
}

class DataCreator {
  private static final String DEFAULT_FILE = "data.ser";

  private static Calendar dateCreator = Calendar.getInstance();

  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() {
    ArrayList appointments = new ArrayList();
    ArrayList contacts = new ArrayList();
    contacts.add(new ContactImpl("Test", "Subject", "Volunteer",
        "United Patterns Consortium"));
    Location location1 = new LocationImpl("Punxsutawney, PA");
    appointments.add(new Appointment("Slowpokes anonymous", contacts,
        location1, createDate(2001, 1, 1, 12, 01), createDate(2001, 1,
            1, 12, 02)));
    appointments.add(new Appointment("Java focus group", contacts,
        location1, createDate(2001, 1, 1, 12, 30), createDate(2001, 1,
            1, 14, 30)));
    appointments
        .add(new Appointment("Something else", contacts, location1,
            createDate(2001, 1, 1, 12, 01), createDate(2001, 1, 1,
                12, 02)));
    appointments.add(new Appointment("Yet another thingie", contacts,
        location1, createDate(2001, 1, 1, 12, 01), createDate(2001, 1,
            1, 12, 02)));
    return appointments;
  }

  private static void serializeToFile(Serializable content, String fileName)
      throws IOException {
    ObjectOutputStream serOut = new ObjectOutputStream(
        new FileOutputStream(fileName));
    serOut.writeObject(content);
    serOut.close();
  }

  public static Date createDate(int year, int month, int day, int hour,
      int minute) {
    dateCreator.set(year, month, day, hour, minute);
    return dateCreator.getTime();
  }
}

class Appointment implements Serializable {
  private String reason;

  private ArrayList contacts;

  private Location location;

  private Date startDate;

  private Date endDate;

  public Appointment(String reason, ArrayList contacts, Location location,
      Date startDate, Date endDate) {
    this.reason = reason;
    this.contacts = contacts;
    this.location = location;
    this.startDate = startDate;
    this.endDate = endDate;
  }

  public String getReason() {
    return reason;
  }

  public ArrayList getContacts() {
    return contacts;
  }

  public Location getLocation() {
    return location;
  }

  public Date getStartDate() {
    return startDate;
  }

  public Date getEndDate() {
    return endDate;
  }

  public void setReason(String reason) {
    this.reason = reason;
  }

  public void setContacts(ArrayList contacts) {
    this.contacts = contacts;
  }

  public void setLocation(Location location) {
    this.location = location;
  }

  public void setStartDate(Date startDate) {
    this.startDate = startDate;
  }

  public void setEndDate(Date endDate) {
    this.endDate = endDate;
  }

  public String toString() {
    return "Appointment:" + "\n    Reason: " + reason + "\n    Location: "
        + location + "\n    Start: " + startDate + "\n    End: "
        + endDate + "\n";
  }
}

class CalendarEditor {
  private State currentState;

  private File appointmentFile;

  private ArrayList appointments = new ArrayList();

  private static final String DEFAULT_APPOINTMENT_FILE = "appointments.ser";

  public CalendarEditor() {
    this(DEFAULT_APPOINTMENT_FILE);
  }

  public CalendarEditor(String appointmentFileName) {
    appointmentFile = new File(appointmentFileName);
    try {
      appointments = (ArrayList) FileLoader.loadData(appointmentFile);
    } catch (ClassCastException exc) {
      System.err
          .println("Unable to load information. The file does not contain a list of appointments.");
    }
    currentState = new CleanState();
  }

  public void save() {
    currentState.save();
  }

  public void edit() {
    currentState.edit();
  }

  private class DirtyState implements State {
    private State nextState;

    public DirtyState(State nextState) {
      this.nextState = nextState;
    }

    public void save() {
      FileLoader.storeData(appointmentFile, appointments);
      currentState = nextState;
    }

    public void edit() {
    }
  }

  private class CleanState implements State {
    private State nextState = new DirtyState(this);

    public void save() {
    }

    public void edit() {
      currentState = nextState;
    }
  }

  public ArrayList getAppointments() {
    return appointments;
  }

  public void addAppointment(Appointment appointment) {
    if (!appointments.contains(appointment)) {
      appointments.add(appointment);
    }
  }

  public void removeAppointment(Appointment appointment) {
    appointments.remove(appointment);
  }
}

class StateGui implements ActionListener {
  private JFrame mainFrame;

  private JPanel controlPanel, editPanel;

  private CalendarEditor editor;

  private JButton save, exit;

  public StateGui(CalendarEditor edit) {
    editor = edit;
  }

  public void createGui() {
    mainFrame = new JFrame("State Pattern Example");
    Container content = mainFrame.getContentPane();
    content.setLayout(new BoxLayout(content, BoxLayout.Y_AXIS));

    editPanel = new JPanel();
    editPanel.setLayout(new BorderLayout());
    JTable appointmentTable = new JTable(new StateTableModel(
        (Appointment[]) editor.getAppointments().toArray(
            new Appointment[1])));
    editPanel.add(new JScrollPane(appointmentTable));
    content.add(editPanel);

    controlPanel = new JPanel();
    save = new JButton("Save Appointments");
    exit = new JButton("Exit");
    controlPanel.add(save);
    controlPanel.add(exit);
    content.add(controlPanel);

    save.addActionListener(this);
    exit.addActionListener(this);

    mainFrame.addWindowListener(new WindowCloseManager());
    mainFrame.pack();
    mainFrame.setVisible(true);
  }

  public void actionPerformed(ActionEvent evt) {
    Object originator = evt.getSource();
    if (originator == save) {
      saveAppointments();
    } else if (originator == exit) {
      exitApplication();
    }
  }

  private class WindowCloseManager extends WindowAdapter {
    public void windowClosing(WindowEvent evt) {
      exitApplication();
    }
  }

  private void saveAppointments() {
    editor.save();
  }

  private void exitApplication() {
    System.exit(0);
  }

  private class StateTableModel extends AbstractTableModel {
    private final String[] columnNames = { "Appointment", "Contacts",
        "Location", "Start Date", "End Date" };

    private Appointment[] data;

    public StateTableModel(Appointment[] appointments) {
      data = appointments;
    }

    public String getColumnName(int column) {
      return columnNames[column];
    }

    public int getRowCount() {
      return data.length;
    }

    public int getColumnCount() {
      return columnNames.length;
    }

    public Object getValueAt(int row, int column) {
      Object value = null;
      switch (column) {
      case 0:
        value = data[row].getReason();
        break;
      case 1:
        value = data[row].getContacts();
        break;
      case 2:
        value = data[row].getLocation();
        break;
      case 3:
        value = data[row].getStartDate();
        break;
      case 4:
        value = data[row].getEndDate();
        break;
      }
      return value;
    }

    public boolean isCellEditable(int row, int column) {
      return ((column == 0) || (column == 2)) ? true : false;
    }

    public void setValueAt(Object value, int row, int column) {
      switch (column) {
      case 0:
        data[row].setReason((String) value);
        editor.edit();
        break;
      case 1:
        break;
      case 2:
        data[row].setLocation(new LocationImpl((String) value));
        editor.edit();
        break;
      case 3:
        break;
      case 4:
        break;
      }
    }
  }
}


           
       

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