Thread: Jtable only updates at the end of a buton event.

My problem is the following :

I have a jtable that displays some data in the rows.
I have a button whose event is to loop slowly through the rows of this table and change the values of the data - in this case flip true/false .. and slowly is due to a sleep (The actual problem I have is a lengthy calculation)
I would like the table to update after each change, as it currently only updates at the end of the button event.
What am i doing wrong ? I have tried all sorts of combinations.


The (self contained) code that demonstrates the problem is below -
I have adapted the TableDemo example for the orcale/java How to Use Tables tutorial

 
/** 
 * TableDemo is just like SimpleTableDemo, except that it
 * uses a custom TableModel.
 */
public class TableDemo extends JPanel {
 
    private JButton looper;
    JTable table;
    MyTableModel mdl;
    private static JFrame frame;
 
    public TableDemo() {
        super(new GridLayout(2,0));
 
        looper = new JButton();
        looper.setText("Hit Me to loop thru table and flip vegetarian preference");
 
        looper.addActionListener(new java.awt.event.ActionListener() {
            @Override
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                HitButtonActionPerformed(evt);
            }
        });
 
        mdl = new MyTableModel();       
        table = new JTable(mdl);
        table.setPreferredScrollableViewportSize(new Dimension(500, 70));
        table.setFillsViewportHeight(true);
 
        //Create the scroll pane and add the table to it.
        JScrollPane scrollPane = new JScrollPane(table);
 
        //Add the scroll pane to this panel.
        add(scrollPane);
        //add button
        add(looper);
    }
 
    public void HitButtonActionPerformed(ActionEvent e) {
 
        for (int row=0; row<table.getRowCount();row++)
        {
            try {
                Thread.currentThread().sleep(1000);//sleep for 1000 ms
                System.out.println("one more flip");
 
                Object p = table.getValueAt(row, 4);
                table.setValueAt( !((Boolean)p), row, 4);
 
                /* no hope
                ( (AbstractTableModel)table.getModel()).fireTableCellUpdated(row, 4);
                mdl.fireTableCellUpdated(row, 4);
                mdl.fireTableDataChanged();
                table.validate();  
                frame.repaint();
                */
 
            } catch (InterruptedException ex) {
                Logger.getLogger(TableDemo.class.getName()).log(Level.SEVERE, null, ex);
            }
 
        }
    }
 
    class MyTableModel extends AbstractTableModel {
        private String[] columnNames = {"First Name",
                                        "Last Name",
                                        "Sport",
                                        "# of Years",
                                        "Vegetarian"};
        private Object[][] data = {
        {"Kathy", "Smith","Snowboarding", new Integer(5), false},
        {"John", "Doe","Rowing", new Integer(3), true},
        {"Sue", "Black", "Knitting", new Integer(2), false},
        {"Jane", "White", "Speed reading", new Integer(20), true},
        {"Joe", "Brown","Pool", new Integer(10), false}
        };
 
        @Override
        public int getColumnCount() {
            return columnNames.length;
        }
 
        @Override
        public int getRowCount() {
            return data.length;
        }
 
        @Override
        public String getColumnName(int col) {
            return columnNames[col];
        }
 
        @Override
        public Object getValueAt(int row, int col) {
            return data[row][col];
        }
 
        /*
         * JTable uses this method to determine the default renderer/
         * editor for each cell.  If we didn't implement this method,
         * then the last column would contain text ("true"/"false"),
         * rather than a check box.
         */
        @Override
        public Class getColumnClass(int c) {
            return getValueAt(0, c).getClass();
        }
 
        /*
         * Don't need to implement this method unless your table's
         * editable.
         */
        @Override
        public boolean isCellEditable(int row, int col) {
            //Note that the data/cell address is constant,
            //no matter where the cell appears onscreen.
            if (col < 2) {
                return false;
            } else {
                return true;
            }
        }
 
        /*
         * Don't need to implement this method unless your table's
         * data can change.
         */
        @Override
        public void setValueAt(Object value, int row, int col) {          
            data[row][col] = value;
            fireTableCellUpdated(row, col);
        }
    }
 
    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Create and set up the window.
        frame = new JFrame("TableDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
        //Create and set up the content pane.
        TableDemo newContentPane = new TableDemo();
        newContentPane.setOpaque(true); //content panes must be opaque
        frame.setContentPane(newContentPane);
 
        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }
 
    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    } 
}