JTable load values on change, display progressbar while loading

Question

So i am working with a JTable, It has Columns A-K. with A and B being the only editable ones. If someone edits an empty row in A, I make an API call to get B then i make a DB call to get all rows where B exists.If someone edits an empty row in B, i make the same call as the will be retrieved from the DB for that row as well. The call returns 0-N rows. If 0 rows were returned, I change the values of all row except B to N/A otherwise i populate the rows using the data.Once populated, i make all columns non-editable. The DB call occurs in its own thread as once the call is return i create my own record object which I add to the tablemodel.

I have my own TableModel and a TableModelListener to keep the data and handle changes in values.

Here is my issue. I am using TableCellRenderer and using the cellrenderer to see if the value was changed, if so then i make the calls and populate as needed. When a large number of rows is being pulled from DB, it takes a while to load and making all that records so I tried to use a ProgressBar to show the user that the screen isn't just frozen, it is progressing and by how much. However the frame that comes up is blank and nothing gets displayed. I get the feeling i am doing something either improperly or missing something.Any help much appreciated.

some code to understand what i am talking about

public class MyPanel extends JPanel {
    private JTable myTable;
    private MyTableModel tm;
    //OTHER FIELDS

    public static void createPanel() {
           tm = new MyTableModel(columnnames);
           myTable = new JTable(tm);

           TableColumn account = myTable.getColumnModel().getColumn(
            MyTableModel.ACCOUNT_INDEX);
    account.setCellRenderer(new MyTableRenderer(
            MyTableModel.ACCOUNT_INDEX));
    }
}

public class MyTableRenderer extends DefaultTableCellRenderer{

   protected int interactiveColumn;

   public MyTableRenderer(int interactiveColumn) {
        this.interactiveColumn = interactiveColumn;
    }

   public Component getTableCellRendererComponent(JTable table,
            Object value, boolean isSelected, boolean hasFocus, int row,
            int column) {
        Component c = super.getTableCellRendererComponent(table, value,
                isSelected, hasFocus, row, column);
        if (column == interactiveColumn && hasFocus) {
             //DO DB and API CALLS HERE
             //IF DB CALL DISPLAY A NEW FRAME WITH PROGRESSBAR
        }
        return c;
   }
}

Sorry for formatting issues

Answer 1

Use SwingWorker, which allows you to update your TableModel as you examine your result set.

Addendum: Don't try to update the TableModel from the renderer. You can update the model when your implementation of CellEditor has concluded, by starting a suitable worker in getCellEditorValue(). In that way, the revised data will be available when the renderer is next invoked for any modified cell(s). This related example outlines the approach.

Addendum: getCellEditorValue() is invoked after editing has concluded, but starting the worker in setValueAt() offers more reliable access to the target row and column.