Re: Question on MVC model

From: (Stefan Ram)
4 Sep 2006 13:12:28 GMT
"Suma Shanbhog" <> writes:

That is, if any new control has to be added, I have to add a
model, a view class and a controller class...

  You need a view, controller and model /object/.

    - Multiple objects might share a class when appropriate.

    - Multiple views and controllers might share a model
      when appropriate.

Inspite of this is there scope for any design pattern to be used for
communication between these classes??

  The communication is also treated in MVC.

I always felt that just following MVC should eb sufficient...

  Nowadays there are multiple different architectures labeled
  "MVC", differing more or less from the original MVC.

  Moreover, Swing uses a variant that might be called
  "UI-delegate and model".

  The most pragmatic approach might be to forget MVC for
  the moment and learn Swing by Sun's Swing tutorial.

I know this may not be the right forum for this kind of
question but I didn't locate any group discussing design.

  See also:

  If one really tries to use the original MVC

  in Java, it might look like this attempt of mine to
  implement a simple toggle-button:

public class ButtonModel
{ public static void main( final java.lang.String[] args )
  { javax.swing.SwingUtilities.invokeLater( new FrameController() ); }}

class FrameView
{ FrameController controller = null;
  Button1View button = null;
  javax.swing.JFrame frame = null; /* MVC "subView" */
  public FrameView()
  { frame = new javax.swing.JFrame( "MVC" );
    ( javax.swing.JFrame.DO_NOTHING_ON_CLOSE );
    final Button1Model model = new Button1Model();
    final Button1Controller controller = new Button1Controller();
    controller.setModel( model );
    button = new Button1View( frame, model, controller );
    frame.pack(); frame.setVisible( true ); }
  public void setController // MVC "model:controller:"
  ( final FrameController controller )
  { this.controller = controller;
    this.controller.setView( this );
    frame.addWindowListener( this.controller ); }
  public void releaseController() /* MVC "release" */
  { frame.removeWindowListener( this.controller );
    this.controller = null; }
  public void dispose() /* MVC "release" */
  { this.button.dispose(); this.button = null;
    this.frame.dispose(); this.frame = null; }}

class FrameController // MVC "Top-Level Controller
implements java.lang.Runnable, // MVC "StandardSystemController"
{ FrameView view = null;
  public void setView( final FrameView view ) /* MVC "view" */
  { this.view = view; }
  public void releaseView()
  { this.view = null; }
  public void run() // MVC "open" (cto)
  { FrameView view = new FrameView();
    view.setController( this ); }
  public void windowClosing /* MVC "terminate" */
  ( final java.awt.event.WindowEvent e )
  { FrameView view = this.view;
    view.dispose(); }
  public void windowOpened( final java.awt.event.WindowEvent e ){}
  public void windowDeactivated( final java.awt.event.WindowEvent e ){}
  public void windowDeiconified( final java.awt.event.WindowEvent e ){}
  public void windowIconified( final java.awt.event.WindowEvent e ){}
  public void windowActivated( final java.awt.event.WindowEvent e ){}
  public void windowClosed( final java.awt.event.WindowEvent e){} }

class Button1View /* MVC "view" */
implements java.beans.PropertyChangeListener
{ javax.swing.JButton button = null;
  javax.swing.JFrame frame = null;
  Button1Model button1Model = null;
  private java.lang.String labelText( final boolean state )
  { return state ? "ausschalten" : "einschalten"; }
  public Button1View /* MVC "model:controller" (va3) */
  ( final javax.swing.JFrame frame,
    final Button1Model button1Model,
    final java.awt.event.ActionListener controller )
  { assert javax.swing.SwingUtilities.isEventDispatchThread();
    this.button1Model = button1Model;
    this.button = new javax.swing.JButton( labelText( this.button1Model.isOn() ));
    this.button.addActionListener( controller );
    this.button1Model.addButton1Listener( this );
    this.frame = frame;
    this.frame.add( this.button ); }
  public void propertyChange
  ( java.beans.PropertyChangeEvent propertyChangeEvent )
  { java.lang.System.out.println( "changed" );
    this.button.setText( labelText( this.button1Model.isOn() )); }
  public void dispose()
  { this.button1Model.removeButton1Listener( this );
    this.frame.remove( this.button );
    this.button = null; }}

class Button1Controller
implements java.awt.event.ActionListener
{ Button1Model button1Model = null;
  public void setModel( final Button1Model button1Model )
  { this.button1Model = button1Model; }
  public void actionPerformed /* MVC event (cpe) */
  ( final java.awt.event.ActionEvent actionEvent )
  { button1Model.toggle(); }}

class Button1Model
{ private boolean state = false;
  javax.swing.event.SwingPropertyChangeSupport listeners;
  public Button1Model()
  { listeners =
    new javax.swing.event.SwingPropertyChangeSupport( this ); }
  public boolean isOn(){ return state; }
  public void toggle(){ state = !state; changedState(); }
  private void changedState()
  { this.listeners.firePropertyChange
    ( new java.beans.PropertyChangeEvent
      ( this, "on", state, !state )); }
  public void addButton1Listener
  ( final java.beans.PropertyChangeListener l )
  { this.listeners.addPropertyChangeListener( l ); }
  public void removeButton1Listener
  ( final java.beans.PropertyChangeListener l )
  { this.listeners.removePropertyChangeListener( l ); }}

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