Simple MVC desktop example wanted

Question

Hi,
I've been looking and can't find a good example of MVC in a desktop application. I don't mean MVC as it is used in component development (I've seen some examples relating to Swing and Buttonmodels, for instance), but more business-object level. I'm not a Java or Swing expert, but I have been programming for a while and and am pretty comfortable writing non-UI Java classes and simple Swing apps. But I want to know how to do this right.
Here's the simplest example I can think of to explain my confusion:
Suppose I have a class called Customer with fields FirstName and LastName. Suppose further I want to create a desktop GUI that allows the customer to edit that model in two separate windows in such a way that changes in one edit window are immediately reflected in the other, and I want clean separation of presentation and logic.
The example doesn't have to be in Swing, but it shouldn't require a server.
Thanks for any help you can give on this - and, if this isn't the right place to post this query, I'd appreciate a pointer to a more appropriate forum.

Answer 1

There are many ways but here is a simple example of how I do it.
******************************* CustomerModel.java
import java.beans.PropertyChangeSupport;
import java.beans.PropertyChangeListener;
public class CustomerModel
    /** Change Support Object */
    private PropertyChangeSupport propertyChangeSupport = new PropertyChangeSupport(this);
    /** bound property names */
    public static final String FIRST_NAME_CHANGED = "firstname";
    public static final String LAST_NAME_CHANGED = "lastname";
    /** First Name Element */
    private String firstName;
    /** Last Name Element */
    private String lastName;
    /** Blank Constructor */
    public CustomerModel()
        super();
     * Sets the first name element.  If value changed a notification is
     * sent to all listeners of this property
     * @param newFirstName String
    public void setFirstName(String newFirstName)
        String oldFirstName = this.firstName;
        this.firstName = newFirstName;
        propertyChangeSupport.firePropertyChange(FIRST_NAME_CHANGED, oldFirstName, newFirstName);
     * @return String
    public String getFristName()
        return firstName;
     * Sets the last name element.  If value changed a notification is
     * sent to all listeners of this property
     * @param newFirstName String
    public void setLastName(String newLastName)
        String oldLastName = this.lastName;
        this.lastName = newLastName;
        propertyChangeSupport.firePropertyChange(LAST_NAME_CHANGED, oldLastName, newLastName);
     * @return String
    public String getLastName()
        return lastName;
    /** Passthrough method for property change listener */
    public void addPropertyChangeListener(String str, PropertyChangeListener pcl)
        propertyChangeSupport.addPropertyChangeListener(str, pcl);       
    /** Passthrough method for property change listener */
    public void removePropertyChangeListener(String str, PropertyChangeListener pcl)
        propertyChangeSupport.removePropertyChangeListener(str, pcl);
}******************************* CustomerFrame.java
import javax.swing.*;
import java.awt.event.*;
import java.awt.GridLayout;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeEvent;
public class CustomerFrame extends JFrame implements ActionListener, PropertyChangeListener
    /** Customer to view/control */
    private CustomerModel customer;
    private JLabel firstNameLabel = new JLabel("First Name: ");
    private JTextField firstNameEdit = new JTextField();
    private JLabel lastNameLabel = new JLabel("Last Name: ");
    private JTextField lastNameEdit = new JTextField();
    private JButton updateButton = new JButton("Update");
     * Constructor that takes a model
     * @param customer CustomerModel
    public CustomerFrame(CustomerModel customer)
       // setup this frame
       this.setName("Customer Editor");
       this.setTitle("Customer Editor");
       this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
       this.getContentPane().setLayout(new GridLayout(3, 2));
       this.getContentPane().add(firstNameLabel);
       this.getContentPane().add(firstNameEdit);
       this.getContentPane().add(lastNameLabel);
       this.getContentPane().add(lastNameEdit);
       this.getContentPane().add(updateButton);
       // reference the customer locally
       this.customer = customer;
       // register change listeners
       this.customer.addPropertyChangeListener(CustomerModel.FIRST_NAME_CHANGED, this);
       this.customer.addPropertyChangeListener(CustomerModel.LAST_NAME_CHANGED, this);
       // setup the initial value with values from the model
       firstNameEdit.setText(customer.getFristName());
       lastNameEdit.setText(customer.getLastName());
       // cause the update button to do something
       updateButton.addActionListener(this);
       // now display everything
       this.pack();
       this.setVisible(true);
     * Update the model when update button is clicked
     * @param e ActionEvent
    public void actionPerformed(ActionEvent e)
        customer.setFirstName(firstNameEdit.getText());
        customer.setLastName(lastNameEdit.getText());
        System.out.println("Update Clicked " + e);
     * Update the view when the model has changed
     * @param evt PropertyChangeEvent
    public void propertyChange(PropertyChangeEvent evt)
        if (evt.getPropertyName().equals(CustomerModel.FIRST_NAME_CHANGED))
            firstNameEdit.setText((String)evt.getNewValue());
        else if (evt.getPropertyName().equals(CustomerModel.LAST_NAME_CHANGED))
            lastNameEdit.setText((String)evt.getNewValue());
}******************************* MainFrame.java
import javax.swing.JFrame;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JButton;
public class MainFrame extends JFrame implements ActionListener
    /** Single customer model to send to all spawned frames */
    private CustomerModel model = new CustomerModel();
    /** Button to click to spawn new frames */
    private JButton newEditorButton = new JButton("New Editor");
    /** Blank Constructor */
    public MainFrame() {
        super();
    /** Create and display the GUI */
    public void createAndDisplayGUI()
        this.setName("MVC Spawner");
        this.setTitle("MVC Spawner");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.newEditorButton.addActionListener(this);
        this.getContentPane().add(newEditorButton);
        this.pack();
        this.setVisible(true);
    /** Do something when the button is clicked */
    public void actionPerformed(ActionEvent e)
        new CustomerFrame(model);
     * Creates the main frame to spawn customer edit frames from.
     * @param args String[] ignored
    public static void main(String[] args) {
        MainFrame mainframe = new MainFrame();
        mainframe.createAndDisplayGUI();
}