Frustrated with simple JTable issue....very simple..aggghhhh

Question

I'm trying to create a JTable with currency fileds, and other types as well. It would display currency format but wipe off the dollar signs when the user edits the field and allow the user to enter numbers without dollar signs.
I was able to do this for a textfield using the online tutorial but having problem creating it for a JTable.
This is because the example that I'm using creates the table with its data hardcoded...I need to pass data to the table at runtime.
If I mod the code's constructor to receive data and columnNames, I'd get a Null pointer error because the the first thing the constructor would try to getRowCount which it references ddata...data is not yet assigned a value.
Here's the tutorial sample codes...
public TableDemo() {
JTable table = new JTable(new MyTableModel());
class MyTableModel extends AbstractTableModel {
private String[] columnNames = ...//same as before...
private Object[][] data = ...//same as before...
public int getColumnCount() {
return columnNames.length;
public int getRowCount() {
return data.length;
public String getColumnName(int col) {
return columnNames[col];
public Object getValueAt(int row, int col) {
return data[row][col];
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) {
data[row][col] = value;
fireTableCellUpdated(row, col);
I just need to make this table NOT having the data and columnNames hardcoded...or if someone has some niffty currency edits...
Thanks so much

Answer 1

Your question still doesn't make any sense to me. From your last posting I suggested you should be using the DefaultTableModel, since you apparently don't understand how to write your own custom TableModel. The DefaultTableModel allows you to create a TableModel loaded with data or you can create an empty DefaultTableModel and add rows of data to it as required.
I need to pass data to the table at runtime.Again you seem confused. What is the difference between hardcoding data and reading data from a file at runtime? None.
The basic coding structure would be:
a) create TableModel
b) JTable table = new JTable( model );
Create a method called createTableModel. In that method you either hardcode a table or add logic to read data from a file, read data froma database. It doesn't matter where the data comes from as long as you createTableModel method returns a TableModel.
In your last posting I gave you a link to a simple working demo. Start with that as your base code and try to customize it. The code you posted here is useless. We can't solve problems based on a few lines of code.
Here is another example showing how to add rows of data dynamicallly:
http://forum.java.sun.com/thread.jspa?forumID=57&threadID=577919
Use the "code" tags any time you post code.