Highlights subString in the TableCell(s) which is using for JTable filetering

JXTable can do so via a Highlighter – see swinglabs-demos for an example (MatchingTextHighlighter in the search demo) – there a background highlight is applied by a Painter.

You can do something like that manually somewhere in your renderer. If using a JLabel as renderingComponent, you basically have to find parts of the text that need the background highlight and paint the background for that region (below is a code snippet for finding the areas, c&p from the demos example). Alternatively you might consider using a JTextField as rendering component: the adv is that Highlighter (from javax.swing.text) is built-in, the disadv are the usual issues with text comps as renderers 😉

/**
 * Finds the rectangles that contain rendered characters that match the
 * pattern.
 * 
 * @param object an optional configuration parameter. This may be null.
 * @param width width of the area to paint.
 * @param height height of the area to paint.
 * @return a <code>List</code> of <code>Rectangle</code>s marking characters
 *         to highlight
 */
protected List<Rectangle> findHighlightAreas(JLabel object, int width,
        int height) {
    String text = object.getText();

    insets = object.getInsets(insets);

    viewR.x = 0 + insets.left;
    viewR.y = 0 + insets.bottom;
    viewR.width = width - insets.right;
    viewR.height = height - insets.top;

    // Reset the text and view rectangle x any y coordinates.
    // These are not set to 0 in SwingUtilities.layoutCompoundLabel
    iconR.x = iconR.y = 0;
    textR.x = textR.y = 0;

    FontMetrics fm = object.getFontMetrics(object.getFont());
    String clippedText = SwingUtilities.layoutCompoundLabel(object, fm,
            text, object.getIcon(), object.getVerticalAlignment(), object
                    .getHorizontalAlignment(), object
                    .getVerticalTextPosition(), object
                    .getHorizontalTextPosition(), viewR, iconR, textR,
            object.getIconTextGap());

    int xOffset = calculateXOffset(object, viewR, textR);

    String textToSearch = clippedText;
    // Check to see if the text will be clipped
    if (!object.getText().equals(clippedText)) {
        // TODO There has to be a better way that assuming ellipses
        // are the last characters of the text
        textToSearch = clippedText.substring(0, clippedText.length() - 3);
    }

    return createHighlightAreas(textToSearch, fm, xOffset, height);
}

/**
 * Creates the rectangles that contain matched characters in the given text.
 * 
 * @param text the text to search
 * @param fm the font metrics of the rendered font
 * @param xOffset the x offset at which text rendering starts
 * @param height the height of painted highlights
 * @return a <code>List</code> of highlight areas to paint
 */
protected List<Rectangle> createHighlightAreas(String text, FontMetrics fm,
        int xOffset, int height) {
    SearchPredicate predicate = (SearchPredicate) getHighlightPredicate();
    Matcher matcher = predicate.getPattern().matcher(text);

    List<Rectangle> highlightAreas = null;
    int startFrom = 0;
    while (startFrom < text.length() && matcher.find(startFrom)) {
        if (highlightAreas == null) {
            highlightAreas = new ArrayList<Rectangle>();
        }

        int start = matcher.start();
        int end = matcher.end();

        if (start == end) {
            // empty matcher will cause infinite loop
            break;
        }

        startFrom = end;

        int highlightx;
        int highlightWidth;

        if (start == 0) {
            // start highlight from the start of the field
            highlightx = textR.x + xOffset;
        } else {
            // Calculate the width of the unhighlighted text to
            // get the start of the highlighted region.
            String strToStart = text.substring(0, start);
            highlightx = textR.x + fm.stringWidth(strToStart) + xOffset;
        }

        // Get the width of the highlighted region
        String highlightText = text.substring(start, end);
        highlightWidth = fm.stringWidth(highlightText);

        highlightAreas.add(new Rectangle(highlightx, 0, highlightWidth,
                height));
    }

    if (highlightAreas == null) {
        highlightAreas = Collections.emptyList();
    } else {
        coalesceHighlightAreas(highlightAreas);
    }
    return highlightAreas;
}

/**
 * Joins highlight rectangles that mark adjacent horizontal areas into
 * single rectangles. This is useful to renderers that vary horizontally,
 * such a horizontal gradient - the gradient will not restart when there are
 * two adjacent highlight areas.
 * 
 * @param highlightAreas a <code>List</code> of <code>Rectangle</code>s.
 */
protected void coalesceHighlightAreas(List<Rectangle> highlightAreas) {
    Collections.sort(highlightAreas, X_AXIS_RECTANGLE_COMPARATOR);

    int i = 0;
    while (i < highlightAreas.size() - 1) {
        Rectangle r1 = highlightAreas.get(i);
        Rectangle r2 = highlightAreas.get(i + 1);

        if (r1.x + r1.width == r2.x) {
            r1.width += r2.width;
            highlightAreas.remove(i + 1);
        } else {
            i++;
        }
    }
}

/**
 * Calculates the x offset of highlights based on component orientation and
 * text direction.
 * 
 * @param component the renderer component
 * @param viewR the view rectangle of the renderer component
 * @param textR the text rectangle of the renderer component
 * @return the number of pixels to offset the highlight from the left edge
 *         of the component
 */
protected int calculateXOffset(JLabel component, Rectangle viewR,
        Rectangle textR) {
    int horizAlignment = component.getHorizontalAlignment();
    boolean leftToRight = component.getComponentOrientation()
            .isLeftToRight();

    if (horizAlignment == SwingConstants.LEFT
            || (horizAlignment == SwingConstants.LEADING && leftToRight)
            || (horizAlignment == SwingConstants.TRAILING && !leftToRight)) {
        return 0;
    } else if (horizAlignment == SwingConstants.RIGHT
            || (horizAlignment == SwingConstants.TRAILING && !leftToRight)
            || (horizAlignment == SwingConstants.LEADING && leftToRight)) {
        return viewR.width - textR.width;
    } else if (horizAlignment == SwingConstants.CENTER) {
        return (viewR.width - textR.width) / 2;
    }
    throw new AssertionError("Unknown horizonal alignment "
            + horizAlignment);
}