JTableの検索結果をRowFilterとHighlighterで強調表示する

class HighlightTableCellRenderer
    extends JTextField implements TableCellRenderer {
  private static final Color BGC= new Color(220, 240, 255);
  private final transient Highlighter.HighlightPainter highlightPainter
    = new DefaultHighlighter.DefaultHighlightPainter(Color.YELLOW);
  private String pattern = "";
  private String prev;

  public boolean setPattern(String str) {
    if (str == null || str.equals(pattern)) {
      return false;
    } else {
      prev = pattern;
      pattern = str;
      return true;
    }
  }

  public HighlightTableCellRenderer() {
    super();
    setOpaque(true);
    setBorder(BorderFactory.createEmptyBorder());
    setForeground(Color.BLACK);
    setBackground(Color.WHITE);
    setEditable(false);
  }

  @Override public Component getTableCellRendererComponent(
      JTable table, Object value, boolean isSelected,
      boolean hasFocus, int row, int column) {
    String txt = Objects.toString(value, "");
    Highlighter highlighter = getHighlighter();
    highlighter.removeAllHighlights();
    setText(txt);
    setBackground(isSelected ? BGC : Color.WHITE);
    if (pattern != null && !pattern.isEmpty() && !pattern.equals(prev)) {
      Matcher matcher = Pattern.compile(pattern).matcher(txt);
      int pos = 0;
      while (matcher.find(pos) && !matcher.group().isEmpty()) {
        int start = matcher.start();
        int end   = matcher.end();
        try {
          highlighter.addHighlight(start, end, highlightPainter);
        } catch (BadLocationException | PatternSyntaxException e) {
          e.printStackTrace();
        }
        pos = end;
      }
    }
    return this;
  }
}