我在颤振中正确运行 multi_select_flutter 小部件时遇到问题

Question

您好，我正在尝试multi_select_flutter，但无法解决此错误

“List

这是我正在使用的multi_select_flutter 小部件的代码

MultiSelectBottomSheetField(
                  initialChildSize: 0.4,
                  listType: MultiSelectListType.CHIP,
                  searchable: true,
                  buttonText: Text("Favorite Animals"),
                  title: Text("Animals"),
                  items: _items,
                  onConfirm: (values) {
                    // _selectedAnimals2 = values;
                  },
                  chipDisplay: MultiSelectChipDisplay(
                    onTap: (value) {
                      setState(() {
                        _selectedAnimals2.remove(value);
                      });
                    },
                  ),
                ),

我尝试将 _selectedAnimals2 更改为类型转换对象，然后此错误消失但我无法进一步使用它

我尝试在 onConfirm 中打印值，但它只显示 Animal 的实例，但我无法访问与动物类相关的任何字段

这里是完整代码

class Animal {
  final int? id;
  final String? name;

  Animal({
    this.id,
    this.name,
  });
}

我在这里声明列表

  static final List<Animal> _animals = [
    Animal(id: 1, name: "Lion"),
    Animal(id: 2, name: "Flamingo"),
    Animal(id: 3, name: "Hippo"),
    Animal(id: 4, name: "Horse"),
    Animal(id: 5, name: "Tiger"),
    Animal(id: 6, name: "Penguin"),
    Animal(id: 7, name: "Spider"),
    Animal(id: 8, name: "Snake"),
    Animal(id: 9, name: "Bear"),
    Animal(id: 10, name: "Beaver"),
    Animal(id: 11, name: "Cat"),
    Animal(id: 12, name: "Fish"),
    Animal(id: 13, name: "Rabbit"),
    Animal(id: 14, name: "Mouse"),
    Animal(id: 15, name: "Dog"),
    Animal(id: 16, name: "Zebra"),
    Animal(id: 17, name: "Cow"),
    Animal(id: 18, name: "Frog"),
    Animal(id: 19, name: "Blue Jay"),
    Animal(id: 20, name: "Moose"),
    Animal(id: 21, name: "Gecko"),
    Animal(id: 22, name: "Kangaroo"),
    Animal(id: 23, name: "Shark"),
    Animal(id: 24, name: "Crocodile"),
    Animal(id: 25, name: "Owl"),
    Animal(id: 26, name: "Dragonfly"),
    Animal(id: 27, name: "Dolphin"),
  ];
  final _items = _animals
      .map((animal) => MultiSelectItem<Animal>(animal, animal.name!))
      .toList();

  List<Animal?> _selectedAnimals2 = [];

  final _multiSelectKey = GlobalKey<FormFieldState>();

这里是代码

Container(
                    width: 0.9.sw,
                    height: 150.0.h,
                    decoration: const BoxDecoration(
                      color: Colors.white24,
                      borderRadius: BorderRadius.all(
                        Radius.circular(10),
                      ),
                    ),
                    child: MultiSelectBottomSheetField(
                      initialChildSize: 0.4,
                      listType: MultiSelectListType.CHIP,
                      searchable: true,
                      buttonText: const Text("Favorite Animals"),
                      title: const Text("Animals"),
                      items: _items,
                      onConfirm: (values) {
                        _selectedAnimals2 = values;
                      },
                      chipDisplay: MultiSelectChipDisplay(
                        onTap: (value) {
                          setState(() {
                            _selectedAnimals2.remove(value);
                          });
                        },
                      ),
                    ),
                  ),
                  // _selectedAnimals2 == null || _selectedAnimals2.isEmpty
                  //     ? Container(
                  //         padding: EdgeInsets.all(10),
                  //         alignment: Alignment.centerLeft,
                  //         child: Text(
                  //           "None selected",
                  //           style: TextStyle(color: Colors.black54),
                  //         ))
                  //     : Container(),

Answer 1

_items 的元素应该是不可为空的，因为项目声明如下：

类型不匹配是您遇到错误的原因。

你错过了类型参数，检查上面的截图。