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Thread: MVC with MouseListener

  1. #1
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    Default MVC with MouseListener

    I am really stuck on what may be fundamental architectural understanding of how to implement an MVC ( Model-View) Java Application. Any help is really appreciated.

    I have implemented a pretty standard MouseListener in a Jframe. How do I get the mouse click data out of the Listener and into another thread. Most of the online examples show the manipulation of the event data within the scope of the listener object. Something like this is pretty typical:


    public class GUI extends JFrame{

    public GUI() {

    myCanvas = new DrawCanvas();

    MouseAdapter mouser = new MouseAdapter() {
    @Override
    public void mousePressed(MouseEvent e) {
    System.out.format( "mouse coor: %d %d\n",e.getX(),e.getY() );
    // STUFF ALL YOUR CODE HERE USING e.getX() and e.getY() FOR MOUSE DATA
    }
    };

    myCanvas.addMouseListener(mouser);
    Container cp = getContentPane();
    cp.add(myCanvas, BorderLayout.CENTER);

    }
    }
    class DrawCanvas extends JPanel {
    ..............
    }

    This is great for a nice simple example. But to keep the design modular I have another thread (Model) elsewhere. In addition, I have other listeners such as KeyAdapters, etc... How do I aggregate all these inputs into an object that can be grabbed by another thread. It seems I can't get e.getX() outside the scope of the MouseAdapter instantiation.

    And then i have the same problem of how do I get the model data (graphics) back into the JFrame once it has been computed.


  2. #2
    Super Moderator copeg's Avatar
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    Default Re: MVC with MouseListener

    FWIW Swing is already designed as MVC, its up to you to provide the model/data

    I'm not sure I truly understand the question. See if I have this correct - you have a separate thread that manages your data. Why do you need another thread? And is this one thread, or do you launch many?

    Going by the example you provided, the goal you wish is to modify the data in the listener class or launch a Thread/SwingWorker to do longer tasks - when that is complete update the UI. So to prevent tight integration between classes (which is one of the fundamental keys of Model-View-Controller) construct your own listener system in your data model. Have the View listen to changes in data and update accordingly. In this way, the controller (eg MouseListener) tells the model to update, the model updates, and when complete the model then tells the view to update. Things can be plugged in and out by adding/removing the appropriate listeners.

    See the following for examples: Java SE Application Design With MVC

  3. The Following User Says Thank You to copeg For This Useful Post:

    horvath62 (June 3rd, 2012)

  4. #3
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    Default Re: MVC with MouseListener

    Thanks copeg. Your simple explanation of how it works helps alot!

    My struggle with MVC was knowing how to implement the listeners and observers, and getting data to flow between them. I found these two simple code examples which fully implement MVC. As usual having actual working code examples are huge. I hope others will find these useful as well....


    MVC Pattern

    The simplest Model View Controller (MVC) Java example

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