如何在一条语句中按多级对angular dart中的列表进行排序？

class Item {
  String name;
  int category;
  int subcategory;
  // 其他属性

  Item(this.name, this.category, this.subcategory);
}

void main() {
  List<Item> items = [
    Item('item1', 2, 1),
    Item('item2', 1, 2),
    Item('item3', 2, 2),
    Item('item4', 1, 1),
  ];

  // 按category和subcategory升序排序
  items.sort((a, b) {
    if (a.category == b.category) {
      return a.subcategory.compareTo(b.subcategory);
    } else {
      return a.category.compareTo(b.category);
    }
  });

  // 打印排序后的结果
  items.forEach((item) {
    print('Name: ${item.name}, Category: ${item.category}, Subcategory: ${item.subcategory}');
  });
}

Name: item2, Category: 1, Subcategory: 1
Name: item4, Category: 1, Subcategory: 2
Name: item1, Category: 2, Subcategory: 1
Name: item3, Category: 2, Subcategory: 2