JTreeのノード中の文字列をハイライトする

class HighlightTreeCellRenderer extends JTextField
                                implements TreeCellRenderer {
  private static final Color BACKGROUND_SELECTION_COLOR = new Color(220, 240, 255);
  Highlighter.HighlightPainter highlightPainter =
    new DefaultHighlighter.DefaultHighlightPainter(Color.YELLOW);
  public String q;
  public HighlightTreeCellRenderer() {
    super();
    setOpaque(true);
    setBorder(BorderFactory.createEmptyBorder());
    setForeground(Color.BLACK);
    setBackground(Color.WHITE);
    setEditable(false);
  }

  @Override public Component getTreeCellRendererComponent(
      JTree tree, Object value, boolean isSelected, boolean expanded,
      boolean leaf, int row, boolean hasFocus) {
    String txt = Objects.toString(value, "");
    getHighlighter().removeAllHighlights();
    setText(txt);
    setBackground(isSelected ? BACKGROUND_SELECTION_COLOR : Color.WHITE);
    if (q != null && !q.isEmpty() && txt.startsWith(q)) {
      try {
        getHighlighter().addHighlight(0, q.length(), highlightPainter);
      } catch (BadLocationException e) {
        e.printStackTrace();
      }
    }
    return this;
  }
}