Why never change the notifier in receiving a change event

I posted an answer to Java TableModelListener and Live Feed Listener?, but I get a comment by – kleopatra

nonono - you never change the notifier in receiving a change event. 
As to probable effects, think: nasty loops. As to code sanity, think: 
indecent intimacy. It's the task of the model itself to internally 
update related values if necessary.

can somone to explain me what's Change the notifier in receiving a Change Event, what could be happen, what she really means, because as I tried everything that I know that I only receiving RepaintManager Exceptions from very quickly loop,

I never get another Exception, where

  • I multiplaeyd that to the 50 x 1000 matrix,

  • with prepareRenderer (change Color for possitive/negative value)

  • with refresh rate 175 miliseconds

code demonstrated changing the notifier and two another (maybe correct) way how do that

import java.awt.*;
import java.awt.event.ActionEvent;
import java.util.Random;
import java.util.concurrent.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.DefaultTableModel;

public class ChangeNotifiersOnEvent extends JFrame implements Runnable {

    private static final long serialVersionUID = 1L;
    private boolean runProcess = true;
    private Random random = new Random();
    private javax.swing.Timer timerRun;
    private Executor executor = Executors.newCachedThreadPool();
    private String[] columnNames = {"Source", "Hit", "Last", "Ur_Diff"};
    private JTable table;
    private Object[][] data = {{"Swing Timer", 2.99, 5, 1.01},
        {"Swing Worker", 7.10, 5, 1.010}, {"TableModelListener", 25.05, 5, 1.01}};
    private DefaultTableModel model = new DefaultTableModel(data, columnNames);

    public ChangeNotifiersOnEvent() {
        table = new JTable(model) {

            private static final long serialVersionUID = 1L;

            public Class getColumnClass(int column) {
                return getValueAt(0, column).getClass();
        model.addTableModelListener(new TableModelListener() {

            public void tableChanged(TableModelEvent tme) {
                if (tme.getType() == TableModelEvent.UPDATE) {
                    if (tme.getColumn() == 1 && tme.getLastRow() == 2) {
                        double dbl = ((Double) table.getModel().getValueAt(2, 1))
                                - ((Integer) table.getModel().getValueAt(2, 2));
                        table.getModel().setValueAt(dbl, 2, 3);
                    } else if (tme.getColumn() == 1 && tme.getLastRow() == 0) {
                    } else if (tme.getColumn() == 1 && tme.getLastRow() == 1) {
                        executor.execute(new MyTask(MyTask.UPDATE_TABLE_COLUMN));
        table.setFont(new Font("Serif", Font.BOLD, 20));
        JScrollPane scrollPane = new JScrollPane(table);
        add(scrollPane, BorderLayout.CENTER);
        new Thread(this).start();

    private void prepareUpdateTableCell() {
        timerRun = new javax.swing.Timer(10, UpdateTableCell());

    private Action UpdateTableCell() {
        return new AbstractAction("Update Table Cell") {

            private static final long serialVersionUID = 1L;

            public void actionPerformed(ActionEvent e) {
                double dbl = ((Double) table.getModel().getValueAt(0, 1))
                        - ((Integer) table.getModel().getValueAt(0, 2));
                table.getModel().setValueAt(dbl, 0, 3);

    public void run() {
        while (runProcess) {
            try {
            } catch (Exception e) {

    private void changeTableValues() {
        Runnable doRun = new Runnable() {

            public void run() {
                table.getModel().setValueAt(random.nextInt(128) + random.nextDouble(), 0, 1);
                table.getModel().setValueAt(random.nextInt(256) + random.nextDouble(), 1, 1);
                table.getModel().setValueAt(random.nextInt(512) + random.nextDouble(), 2, 1);

                table.getModel().setValueAt(random.nextInt(128), 0, 2);
                table.getModel().setValueAt(random.nextInt(128), 1, 2);
                table.getModel().setValueAt(random.nextInt(128), 2, 2);

    private class MyTask extends SwingWorker<Void, Integer> {

        private static final String UPDATE_TABLE_COLUMN = "update";
        private String namePr;
        private double dbl;

        MyTask(String str) {
            this.namePr = str;

        protected Void doInBackground() throws Exception {
            dbl = ((Double) table.getModel().getValueAt(1, 1))
                    - ((Integer) table.getModel().getValueAt(1, 2));
            return null;

        protected void done() {
            SwingUtilities.invokeLater(new Runnable() {

                public void run() {
                    table.getModel().setValueAt(dbl, 1, 3);

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            public void run() {
                ChangeNotifiersOnEvent frame = new ChangeNotifiersOnEvent();
                frame.setLocation(150, 150);


I think she means that if you don't really think about your code then you can introduce an infinite loop.

Most people when when they create the table would probably make columns 1, 2 editable and make column 3 uneditable since column 3 is just the difference between the two columns.

So when they write the TableModelListener they will check for the UPDATE event but forget to check to see which column is updated because they think the table won't allow them to update column 3.

They forget that when the TableModelListener updates column 3 another UPDATE event will be generated thus causing the infinite loop. Of course, proper coding, like in your example, will prevent the loop.

In general, it should not cause an exception.

The second point is about business rules. The business rules should be defined on one place, in this case the model. The data itself and the updating of the data should be done in a single place.

Need Your Help

Help with getting Json Format data from external website

javascript jquery json

I am trying to get Json format data from this website .. http://www.livetraffic.sg/feeds/json

java: Statement.RETURN_GENERATED_KEYS Err:S1000 Exp: Before start of result set

java mysql prepared-statement sqlexception

I used to execute this query with no problems what so ever, but lately i've been having exceptions.

About UNIX Resources Network

Original, collect and organize Developers related documents, information and materials, contains jQuery, Html, CSS, MySQL, .NET, ASP.NET, SQL, objective-c, iPhone, Ruby on Rails, C, SQL Server, Ruby, Arrays, Regex, ASP.NET MVC, WPF, XML, Ajax, DataBase, and so on.