Problems with JTable Renderer

Question

I have a problem with applying a custom renderer. I know the renderer works so thats not the problem. If I do like this:
DefaultTableModel aDefaultTableModel = new DefaultTableModel(data, columnNames);
it works. But if I do like this:
DefaultTableModel aDefaultTableModel;
aDefaultTableModel.setDataVector(data, columNames);
is doesn't, why?

Answer 1

I think maybe it's not the renderer at all. It may be my custom TableModel thats causing problems. Now this doesn't work:
private JTable aTable;
private CustomTableModel aTableModel;
public MyProgram() {
aTableModel = new CustomTableModel();
aTable = new JTable(aTableModel);
aTableModel.setData(data, columnNames);
private class CustomTableModel {
private String[] columnNames = null;
private Object[][] data = null;
public CustomTableModel() {
columnNames = new String[0];
data = new Object[0][0];
... snip
public void setData(Object[][] data, String[] columnNames) {
this.data = data;
this.columnNames = columnNames;
fireTableDataChanged();
... snip
Now, why doesn't that setData method work??