Implementing MVC paradigm in Swing (Java) using Threads

Question

I am trying to implement the MVC paradigm in Java (Swing) using multithreading. Currently, I am extending the View class with the Observer Class and the and the Model Class with the Observable Class and its working fine (MY code is bulit along this example: http://austintek.com/mvc/). The controller class simply calls the corresponding model and view functions and there is a main "glue" program that sets up everything. However, this approach does not utilize threads. Is there any way to implement this by using threads and the Observer/Observable class at the same time?

(My aim is to implement each of the M, V and C as a separate thread)

The following is part of my View code:

public class View implements Observer
{ 

/*************************************** View *************************************
        **
    **  This function is the constructor of the View class.
    **
    **      PRE: <nothing>
    **      POST: the GUI is created and the directory is displayed on the screen.
    **      RETURN: <N/A>
    **
    **/
    View(String name)
    {
        threadName = name;

        //frame in constructor and not an attribute as doesn't need to be visible to whole class
        JFrame frame = new JFrame("simple MVC");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        addElements(frame); // this is implemented separately

        // frame.addWindowListener(new CloseListener());    
        frame.setSize(900, 732);
        // frame.setLocation(100,100);

        /** Display the window **/
        //frame.pack();
        frame.setVisible(true);

    }// View

And following is part of my Model code:

 public class Model extends java.util.Observable
    {
        /****************** variable DECLARATIONS *********************/

    // The hash table in which the directory is stored
    private Hashtable<String, Integer> tel_dir 
                    = new Hashtable<String, Integer>();

    // The path of the telephone directory during runtime
    private URL filePath
            = Model.class.getClassLoader().getResource("directory.txt");

    // the name of the thread
    private String  threadName;
                        /****** private Thread  t; ******/
    // the object in which the message is sent to the view
    private Message message = new Message();

    /** GETTERS and SETTERS **/

    ....


    /*************************************** Model *************************************
    **
    **  This function is the constructor of the model class.
    **
    **      PRE: <nothing>
    **      POST: the telephone directory is input from the file and stored in a hash
    **            table.
    **      RETURN: <N/A>
    **
    **/
    Model(String name)
    {
        int    phone_num;
        String customer_name;
        Scanner scanner = null;
        threadName      = name;

        /** Opening the handle to the file containing the telephone directory **/
        try
        {
            scanner = new Scanner(new File(filePath.getPath()));
        }
        catch (FileNotFoundException e1)
        {
            e1.printStackTrace();
        }

        /** Inputting from the file and storing it in the hash table **/
        while (scanner.hasNextInt())
        {
            phone_num     = scanner.nextInt();
            customer_name = scanner.nextLine();
            customer_name = customer_name.trim();
            tel_dir.put(customer_name, phone_num);
        }

    }// Model

Swing is already playing the role of the view and the controller. How do you want to decouple that? — Olivier Grégoire
– Olivier Grégoire, Commented Apr 26, 2015 at 11:15

Community · Accepted Answer · 2017-05-23 12:01:29Z

3

My aim is to implement each of the M, V and C as a separate thread.

This is probably not a useful division. Swing views must be constructed and manipulated only on the event dispatch thread, and users expect Swing controls to remain responsive, as discussed here.

Instead, run any time-consuming model in the background of a SwingWorker, and update listening views in your implementation of process(). In this example, the view components are updated directly, but you can also fire a custom event for registered listeners, as suggested here. In this example, the chart listens to its data model, series, via SeriesChangeEvent; it responds to the worker's update in process(). You can show progress via a PropertyChangeEvent, as suggested here or here.

edited May 23, 2017 at 12:01

CommunityBot

11 silver badge

answered Apr 26, 2015 at 11:09

trashgod

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