我在ModalBottomSheet中有一个ListView.Builder。 在ListView中，我正在实现下拉列表。每个列表项都有两个。第二个下拉列表的值取决于第一个下拉列表的选定值。
当我在每个下拉列表中选择值时，打印品会显示我在控制台中选择的内容，但不会更新要在UI中显示的值。
我在这里做错了什么？有人可以帮我吗？我为此花了一整天。
在这里，我将提供构建器方法
//drop down variables
List<String> _categoryList = new List<String>();
List<String> _foodsList = new List<String>();
//reference the dropdown lists
List<String> _selectedCat;
List<String> _selectedFood;
ListView.builder(
itemCount: 5,
itemBuilder: (BuildContext context, int index) {
_selectedCat = new List(5) ;
_selectedFood = new List(5) ;
return Container(
margin: EdgeInsets.symmetric(
vertical: 4.0, horizontal: 4.0),
width: MediaQuery.of(context).size.width * 0.95,
decoration: BoxDecoration(
borderRadius: BorderRadius.all(Radius.circular(
10.0,
)),
color: Color(0xFF01816B),
shape: BoxShape.rectangle),
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
mainAxisSize: MainAxisSize.min,
children: [
Padding(
padding: const EdgeInsets.symmetric(
horizontal: 4.0, vertical: 4.0),
child: Row(
mainAxisAlignment:
MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Expanded(
flex: 3,
child: Text(
"Category",
style: kSubContentStyleWhiteLight,
),
),
Expanded(
flex: 3,
child: Text(
"Food Type",
style: kSubContentStyleWhiteLight,
),
),
Expanded(
flex: 2,
child: Text(
"Quantity",
style: kSubContentStyleWhiteLight,
),
),
],
),
),
Padding(
padding: const EdgeInsets.symmetric(
horizontal: 4.0, vertical: 4.0),
child: Row(
mainAxisAlignment:
MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Expanded(
flex: 2,
child: Container(
width:
MediaQuery.of(context).size.width /
3,
padding: EdgeInsets.symmetric(
vertical: 2.0, horizontal: 4.0),
decoration: BoxDecoration(
borderRadius: BorderRadius.all(
Radius.circular(
10.0,
)),
color: Color(0xFF03B898),
shape: BoxShape.rectangle),
child: DropdownButton<String>(
value:_selectedCat[index],
isDense: false,
isExpanded: true,
hint: Text(
'Category',
style: kSubContentStyleWhitSmaller,
),
style:
kSubContentStyleBlackLightSmall,
onChanged:
(String newVal){
setState(() {
_selectedFood[index] = null;
_selectedCat[index] = newVal;
print(_selectedCat[index]);
_foodsList.clear();
for(int i=0; i < _allCatList.length; i++){
if(_allCatList[i].name == _selectedCat[index] ){
foodTypeList = _allCatList[i].foods;
//
for(int j = 0; j<foodTypeList.length; j++){
_foodsList.add(foodTypeList[j].name);
}
}
}
});
},
items: _categoryList.map((cat) {
return new DropdownMenuItem<String>(
child: new Text(cat),
value: cat,
);
}).toList(),
),
),
),
SizedBox(
width: 2.0,
),
Expanded(
flex: 4,
child: Container(
width:
MediaQuery.of(context).size.width /
3,
padding: EdgeInsets.symmetric(
vertical: 2.0, horizontal: 4.0),
decoration: BoxDecoration(
borderRadius: BorderRadius.all(
Radius.circular(
10.0,
)),
color: Color(0xFF03B898),
shape: BoxShape.rectangle),
child: DropdownButton<String>(
value: _selectedFood[index],
isDense: false,
isExpanded: true,
hint: Text(
'FoodType',
style: kSubContentStyleWhitSmaller,
),
style:
kSubContentStyleBlackLightSmall,
onChanged:
(String newVal){
setState(() {
_selectedFood[index] = newVal;
print(_selectedFood[index]);
});
},
items: _foodsList.map((fdt) { //foodTypeList
return new DropdownMenuItem<String>( // <CATM.Food>(
//<CATM.Food>(
child: new Text(fdt),
value: fdt,
);
}).toList(),
),
),
),
SizedBox(
width: 2.0,
),
Expanded(
flex: 2,
child: Container(
width:
MediaQuery.of(context).size.width /
3,
padding: EdgeInsets.symmetric(
vertical: 2.0, horizontal: 4.0),
decoration: BoxDecoration(
borderRadius: BorderRadius.all(
Radius.circular(
10.0,
)),
color: Color(0xFF03B898),
shape: BoxShape.rectangle),
alignment: Alignment.center,
child: TextFormField(
inputFormatters: [
new LengthLimitingTextInputFormatter(
3),
],
keyboardType: TextInputType.number,
autofocus: false,
validator: validateNumberDecimal,
onSaved: (String value) {
},
style: kSubContentStyleWhitSmaller,
),
),
),
],
),
),
],
),
);
},
),