JListのアイテムをフィルタリングして表示

DefaultListModel<ListItem> model = new DefaultListModel<>();
JList<ListItem> list = new JList<ListItem>(model) {
  @Override public void updateUI() {
    setSelectionForeground(null);
    setSelectionBackground(null);
    setCellRenderer(null);
    super.updateUI();
    setLayoutOrientation(JList.HORIZONTAL_WRAP);
    setVisibleRowCount(0);
    setFixedCellWidth(82);
    setFixedCellHeight(64);
    setBorder(BorderFactory.createEmptyBorder(5, 10, 5, 10));
    setCellRenderer(new ListItemListCellRenderer<ListItem>());
    getSelectionModel().setSelectionMode(
        ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
  }
};

private Optional<Pattern> getPattern() {
  try {
    return Optional.ofNullable(field.getText())
        .filter(s -> !s.isEmpty()).map(Pattern::compile);
  } catch (PatternSyntaxException ex) {
    return Optional.empty();
  }
}

private void filter() {
  getPattern().ifPresent(pattern -> {
    List<ListItem> selected = list.getSelectedValuesList();
    model.clear();
    Stream.of(defaultModel)
        .filter(item -> pattern.matcher(item.title).find()).forEach(model::addElement);
    for (ListItem item : selected) {
      int i = model.indexOf(item);
      list.addSelectionInterval(i, i);
    }
  });
}