Java Programming

Hi All,

Why the following code throwing the null pointer exception?

      public class TableDemo extends JPanel {
  private boolean DEBUG = true;

  public TableDemo() {
    super(new GridLayout(1, 0));
    MyTableModel tablemodel = new MyTableModel();
    tablemodel.setValueAt("Anuuthayam", 0, 0);
    tablemodel.setValueAt("Pon Uthayam", 0, 1);
    tablemodel.setValueAt("Tennis", 0, 2);
    tablemodel.setValueAt("10", 0, 3);
    tablemodel.setValueAt(false, 0, 4);
    JTable table = new JTable(new MyTableModel());
   
    //tablemodel.setValueAt("Anuuthayam", 5, 0);
    table.setPreferredScrollableViewportSize(new Dimension(500, 70));

    //Create the scroll pane and add the table to it.
    JScrollPane scrollPane = new JScrollPane(table);

    //Add the scroll pane to this panel.
    add(scrollPane);
  }

  class MyTableModel extends AbstractTableModel {
    private String[] columnNames = { "First Name", "Last Name", "Sport",
        "# of Years", "Vegetarian" };
    	private Object[][] data = new Object[1][5];
   /* private Object[][] data = {
        { "Mary", "Campione", "Snowboarding", new Integer(5),
            new Boolean(false) },
        { "Alison", "Huml", "Rowing", new Integer(3), new Boolean(true) },
        { "Kathy", "Walrath", "Knitting", new Integer(2),
            new Boolean(false) },
        { "Sharon", "Zakhour", "Speed reading", new Integer(20),
            new Boolean(true) },
        { "Philip", "Milne", "Pool", new Integer(10),
            new Boolean(false) } };*/

    public int getColumnCount() {
      return columnNames.length;
    }

    public int getRowCount() {
      //return data.length;
    	return 1;
    }

    public String getColumnName(int col) {
      return columnNames[col];
    }

    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.
     */
    public Class getColumnClass(int c) {
      return getValueAt(0, c).getClass();
    }

    /*
     * Don't need to implement this method unless your table's editable.
     */
    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.
     */
    public void setValueAt(Object value, int row, int col) {
      System.out.println("Calling this method");
    	if (DEBUG) {
        System.out.println("Setting value at " + row + "," + col
            + " to " + value + " (an instance of "
            + value.getClass() + ")");
      }
      System.out.println(value);
      //super.setValueAt(value, row, col);
      data[row][col] = value;
      super.setValueAt(value, row, col);
     // System.out.println(data[row][col]);
      
      fireTableCellUpdated(row, col);

      if (DEBUG) {
        System.out.println("New value of data:");
        printDebugData();
      }
    }

    private void printDebugData() {
      int numRows = getRowCount();
      int numCols = getColumnCount();

      for (int i = 0; i < numRows; i++) {
        System.out.print("    row " + i + ":");
        for (int j = 0; j < numCols; j++) {
          //System.out.print("  " + data[i][j]);
        }
        System.out.println();
      }
      System.out.println("--------------------------");
    }
  }

  /**
   * Create the GUI and show it. For thread safety, this method should be
   * invoked from the event-dispatching thread.
   */
  private static void createAndShowGUI() {
    //Make sure we have nice window decorations.
    JFrame.setDefaultLookAndFeelDecorated(true);

    //Create and set up the window.
    JFrame 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();
      }
    });
  }
}

Thanks in Advance,
Mahes