Event-Handling: Using one single class for different events?

From:
"S.T" <sascha.tayefeh@googlemail.com>
Newsgroups:
comp.lang.java.programmer
Date:
20 May 2007 11:31:43 -0700
Message-ID:
<1179685903.229935.289980@u36g2000prd.googlegroups.com>
Hi!

 I am rather new to Java, so please, don't blame me for this question.

 What I want is to seperate the GUI- from the Application code. Hence,
I have created three classes:

1. a Main class
2. a MainFrameCommand class, which parses the events
3. a MainFrameGUI class, that creates and paints the gui

(for a trivial example see end of this post)

Now, my question is this: Is it correct, to put all the various events
into one single command class (i.e, Focus-, Key-, Mouse-, and Windows-
Events) and then register the various event-listeners using this
single class?

It works perfectly, however, I wonder if this is a legal way to do so,
or is it necessary to create a seperate class for every different
event-listener-type?

Example:

------------------------------------------------------------
1. Main Class
------------------------------------------------------------
class Main {

    public static void main(final String[] args) {
        MainFrameCommand cmd = new MainFrameCommand();
        MainFrameGUI gui = new MainFrameGUI(cmd);
    }
}

------------------------------------------------------------
2. MainFrameCommand Class
------------------------------------------------------------

import java.awt.*;
import java.awt.event.*;

class MainFrameCommand
implements KeyListener, MouseMotionListener, WindowListener {

    /* Key Listener */
    public void keyPressed(KeyEvent event) {}
    public void keyReleased(KeyEvent event) {}
    public void keyTyped(KeyEvent event) {}

    /* MouseMotion Listener */
    public void mouseMoved(MouseEvent event) {}
    public void mouseDragged(MouseEvent event) {}

    /* WindowListener */
    public void windowClosed(WindowEvent event) {}
    public void windowOpened(WindowEvent event) {}
    public void windowClosing(WindowEvent event) {}
    public void windowActivated(WindowEvent event) {}
    public void windowDeactivated(WindowEvent event) {}
    public void windowIconified(WindowEvent event) {}
    public void windowDeiconified(WindowEvent event) {}
}

------------------------------------------------------------
3. MainFrameGUI Class
------------------------------------------------------------
import java.awt.*;
import java.awt.event.*;

class MainFrameGUI extends Frame {
        public MainFrameGUI(MainFrameCommand cmd) {
        super("Window");
        setSize(300, 300);
        setVisible(true);

/* !!!!!!!!!!!!!!!!!!!!!!! HERE'S THE CRUCIAL QUESTION
   !!!!!!!!!!!!!!!!!!!!!!!
   !!!!!!!!!!!!!!!!!!!!!!! Is it legal to add register all these
   !!!!!!!!!!!!!!!!!!!!!!! event listeners using the same object?!?
*/
        addKeyListener(cmd);
        addWindowListener(cmd);
        addMouseMotionListener(cmd);
    }

    public void paint(Graphics g) {}
}

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