ageColumn, new Comparator&lt;ContactInfo&gt;() {
      @Override
      public int compare(ContactInfo o1, ContactInfo o2) {
        return o1.getAge() - o2.getAge();
      }
    });
    dataGrid.setColumnWidth(4, 7, Unit.EM);

    // Category.
    final Category[] categories = ContactDatabase.get().queryCategories();
    List&lt;String&gt; categoryNames = new ArrayList&lt;String&gt;();
    for (Category category : categories) {
      categoryNames.add(category.getDisplayName());
    }
    SelectionCell cate