How to refresh a JTextField before continuing execution?

Hello:

In several of my Dialogs, I have some phone number, file path, etc. in
a JTextField. Then there is an button that starts some long running
class. My problem is that I would like to convert the {phone number,
SSN, file path} to its canonical form and have the user see it
*before* the long running class starts.

For example, I have a dialog that contains two filepaths with the DOS
backslashes (as returned by JFileChooser), and I would prefer them to
be shown with forward slashes ASAP. Currently, the replacement takes
places after the long running 'ProcessTIFF' instance ends.

final JButton matchAllFilesButton = new JButton();
matchAllFilesButton.addActionListener(new ActionListener() {
    public void actionPerformed(final ActionEvent e) {
        String srcStr = sourceDirTextField.getText().replace('\\',
'/');
        String dstStr = destinDirTextField.getText().replace('\\',
'/');
        sourceDirTextField.setText(srcStr);
        destinDirTextField.setText(dstStr);
        // would like to insert some sort of sleep() or 'redraw' here
        new ProcessTIFF(sourceDirTextField.getText(),
destinDirTextField.getText());
    }
});

I would like to provide a more expedient visual feedback to my users.

TIA,

-Ramon