How can I perform validation of String withing TableCell to get red outline

Question

I have two columns in a JTable, one is defined to be an Integer and one as a String, when they edit the Integer field add enter an non-integral value the DefaultCellEditor outlines the cell in red and prevents them leaving the cell until they have either entered a valid value or cancel the operation (by pressing 'Esc' on Windows).
Where is this behaviour I cant find it in the Java source code, I want to replicate it for a String to do the same thing if the String does not match a regular expression. I have tried subclassing DefaultCellEditor, and and passing an InputVerifier to the text component used to in the construction of the editor degate, but this has had no effect. I also tried overiding stopCellEditing() this had the effect of preventing leaving the cell until they have entered a correct value, but it does not outline it in red
public class ExcelRefCellEditor extends DefaultCellEditor
    public ExcelRefCellEditor(JTextField textfield)
        //@TODO seems to have no effect
        super(textfield);
        textfield.setInputVerifier(new ExcelRefInputVerifier());       
    public boolean stopCellEditing()
        if(!AQExcelRef.isValidForm((String)delegate.getCellEditorValue()))
            return false;
        else
            return delegate.stopCellEditing();
class ExcelRefInputVerifier extends InputVerifier
    public boolean verify(JComponent input)
        return AQExcelRef.isValidForm(((JTextField)input).getText());
class AQExcelRef implements Serializable
    public static boolean isValidForm(String cellRef)
        return cellRef.matches("[A-Z]+[1-9]+");
tc.setCellEditor(new ExcelRefCellEditor(new JTextField()));

Answer 1

Thanks that works perfectly
But I would be interested to know how it it is done for Integer columns as I cant find any code to do this in the DefaultCellEditor, and I took a quick look at the plaf packages and suns internal packages as well.