How to display non-URL-based thumbnail images in JTable

Question

I'm trying to display thumbnail images as a tooltip popup for certain cells in a JTable. The thumbnail images are java image objects that have been retrieved dynamically as the result of a separate process--there is no associated URL. For this reason, I can't use the setToolTipText() method of the JTable.
My attempts to JTable's createToolTip() method also failed as it seems the ToolTipManager never calls this method for a JTable.
As a workaround, I've added a MouseMotionListener to the JTable that detects when the mouse is over the desired table cells. However, I'm not sure how to display the popup over the JTable. The only component that I can get to display over the JTable is a JPopupMenu, but I don't want to display a menu--just the image. Can anyone suggest a way to display a small popup image over the table?
Thanks.

Answer 1

Thank You Rodney. This explains why my createToolTip() method wasn't being called, but unfortunately I'm no closer to my goal of displaying a true custom tooltip using a non-URL image rather than a text string. If I make a call to setToolTipText(), at any point, the text argument becomes the tooltip and everything I have tried in createToolTip() has no effect. However, as you pointed out, if I don't call setToolTipText(), the table is not registered with the tooltip manager and createToolTip() is never even called.
To help clarify, I have attached an SSCCE below. Please note that I use a URL image only for testing. In my actual application, the images are available only as Java objects--there are no URLs.
import javax.swing.*;
import java.awt.*;
import java.net.URL;
import java.net.MalformedURLException;
public class Test {
    static Object[][] data = {
            {"Cell 0,0", "Cell 0,1"},
            {"Cell 1,0", "Cell 1,1"}};
    static String[] columnNames = {"Column 0", "Column 1"};
    static JFrame frame;
    static String testImageURLName = "http://l.yimg.com/k/omg/us/img/7c/0a/4009_4182164952.jpg";
    static JTable testTable = new JTable(data, columnNames) {
        public JToolTip createToolTip() {
            System.out.println("testTable.createToolTip() called");
            Image testImage = getTestImage();
            // this.setToolTipText("Table ToolTip Text");
            JLabel customTipLabel = new JLabel(new ImageIcon(testImage));
            customTipLabel.setToolTipText("Custom ToolTip Text");
            JToolTip parentTip = super.createToolTip();
            parentTip.setComponent(customTipLabel);
            return parentTip;
    // This image is loaded from a URL only for test purposes!!!
    // Ordinarily, the image object would come from the application
    // and no URL would be available.
    public static Image getTestImage() {
        try {
            URL iconURL = new URL(testImageURLName);
            ImageIcon icon = new ImageIcon(iconURL);
            return icon.getImage();
        catch (MalformedURLException ex) {
            JOptionPane.showMessageDialog(frame,
                    "Set variable \"testImageName\" to a valid file name");
            System.exit(1);
        return null;
    public static void main(String[] args) throws Exception {
        frame = new JFrame("Test Table");
        frame.setSize(300, 100);
        // Set tool tip text so that table is registered w/ tool tip manager
        testTable.setToolTipText("main tooltip");
        frame.getContentPane().add(testTable);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
}