如何获得颤振列表中每个元素的索引?

Question

我遇到了一个问题。我在value方法中有一个Checkbox，我需要指定_isChecked[index]。但是我在索引这个词上有个错误。我明白为什么会出错了因为我没有得到每个元素的索引，我没有给出这些。我需要遍历列表中的所有元素来求解吗?或者如何获得所有索引元素?

class DropdownWidget extends StatefulWidget {
List<String> items;
SvgPicture? icon;
double width;
DropdownWidget({
Key? key,
required this.items,
required this.icon,
required this.width,
}) : super(key: key);
@override
State<DropdownWidget> createState() => _DropdownWidgetState();
}
class _DropdownWidgetState extends State<DropdownWidget> {
String? selectedValue;
bool isChecked = false;
List<bool> _isChecked = [];
@override
void initState() {
super.initState();
if (widget.items.isNotEmpty) {
selectedValue = widget.items[1];
}
_isChecked = List<bool>.filled(widget.items.length, false);
}
@override
Widget build(BuildContext context) {
return SizedBox(
width: widget.width,
child: DropdownButtonHideUnderline(
child: DropdownButton2(
items: widget.items
.map((item) => DropdownMenuItem<String>(
value: item,
child: Container(
decoration: BoxDecoration(
border: Border(
bottom: BorderSide(
color: constants.Colors.white.withOpacity(0.1),
width: 1,
),
),
),
child: Center(
child: Row(
children: [
if (item == selectedValue)
const SizedBox(
width: 0,
),
Expanded(
child: Text(
item,
style: constants.Styles.smallTextStyleWhite,
),
),
Checkbox(
value: _isChecked[index],
onChanged: (val) {
setState(() {
_isChecked[index] = val!;
});
},
)
],
),
),
),
))
.toList(),
value: selectedValue,
onChanged: (value) {
setState(() {
selectedValue = value as String;
});
},
icon: SvgPicture.asset(constants.Assets.arrowDropdown),
iconSize: 21,
buttonHeight: 27,
itemHeight: 47,
dropdownMaxHeight: 191,
dropdownWidth: 140,
dropdownDecoration: BoxDecoration(
borderRadius: BorderRadius.circular(8),
border: Border.all(
color: constants.Colors.purpleMain,
),
color: constants.Colors.greyDark,
),
selectedItemBuilder: (context) {
return widget.items.map(
(item) {
return Row(
children: [
widget.icon ?? const SizedBox(),
const SizedBox(width: 8),
Text(
item,
style: constants.Styles.bigBookTextStyleWhite,
),
],
);
},
).toList();
},
),
),
);
}
}

final List<String> carList = const [
"All EV's",
'Main EV',
'<EV2>',
];

Answer 1

您可以将列表转换为映射并迭代其键，键将是元素

的索引

widget.items.asMap().keys.map((index) {
return Container(
child: widget.items[index];
);
}).toList(),