这是我的输出，但当我添加共享首选项时，会显示如下所述的错误.
我在项目中使用了共享首选项依赖关系.在最初打开的应用程序第一下拉值必须是'howmany'和第二下拉值'which'，但当 Select 任何其他值并单击下一步按钮并从移动设备关闭应用程序时，用户重新打开时，则应显示用户 Select 的值.
例如:在初始用户打开的应用程序中，第一个下拉菜单的值必须是"多少"，第二个"哪个"，然后他 Select 第一个下拉菜单"three"，第二个下拉菜单"4th"，并在关闭应用程序并从最近的应用程序中删除后单击下一步按钮.稍后，当他重新打开应用程序时，必须显示下拉值为"three"和"4th"
就像这样
In my code shared preferences works prefcetly for when I use only one drop down but when I used two or more dropdowns then shows this error.个
error个
我的代码
class _FamilyDetailsScreenState extends State<FamilyDetailsScreen> {
// dropdown buttons
String dropdownValueMembers = 'howmany';
// List of items in our dropdown menu
var items = ['howmany', 'one', 'two', 'three ', 'four ', '5 or more'];
void initState() {
super.initState();
checkValueMembers();
checkValueNumber();
}
//IF "dropdownValueMembers" is empty pass "howmany" word as a initial value if al ready selected then pass the shared preference value
checkValueMembers() {
_getData();
}
_saveData(String dropdownValueMembersShared) async {
SharedPreferences sharedPreferences = await SharedPreferences.getInstance();
sharedPreferences.setString("data", dropdownValueMembersShared);
}
_getData() async {
SharedPreferences sharedPreferences = await SharedPreferences.getInstance();
dropdownValueMembers = sharedPreferences.getString("data") ?? "howmany";
setState(() {});
}
// data which child
String dropdownValueNumber = 'which';
// // List of items in our dropdown menu
var number = ['which', '1 st', '2 nd', '3 rd ', '4 th ', '5 th'];
//IF "dropdownValueMembers" is empty pass "which" word as a initial value if al ready selected then pass the shared preference value
checkValueNumber() {
_getDataNumber();
}
_saveDataNumbers(String dropdownValueNumberShared) async {
SharedPreferences sharedPreferences = await SharedPreferences.getInstance();
sharedPreferences.setString("data2", dropdownValueNumberShared);
}
_getDataNumber() async {
SharedPreferences sharedPreferences = await SharedPreferences.getInstance();
dropdownValueMembers = sharedPreferences.getString("data2") ?? "which";
setState(() {});
}
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
resizeToAvoidBottomInset: false,
body: Container(
child: SafeArea(
child: Column(
children: <Widget>[
const Text(
'family details',
textAlign: TextAlign.center,
style: TextStyle(
color: Colors.black,
fontSize: 18.00,
fontWeight: FontWeight.w700,
),
),
const SizedBox(
height: 30,
),
Padding(
padding: const EdgeInsets.only(top: 10, left: 15),
child: Row(
children: <Widget>[
const Icon(
Icons.brightness_1,
color: Colors.black,
size: 10.0,
),
const Padding(
padding: EdgeInsets.only(left: 13),
child: Text(
"Number of children",
style: TextStyle(
fontSize: 15, fontWeight: FontWeight.w600),
),
),
Padding(
padding: const EdgeInsets.only(left: 2),
child: Container(
height: 25,
decoration: BoxDecoration(
boxShadow: const <BoxShadow>[
//apply shadow on Dropdown button
BoxShadow(
color: Color.fromRGBO(
0, 0, 0, 0.37), //shadow for button
blurRadius: 5) //blur radius of shadow
],
color: Colors.white,
borderRadius: BorderRadius.circular(15),
),
child: DropdownButton(
underline: Container(),
borderRadius: BorderRadius.circular(20),
// Initial Value
value: dropdownValueMembers,
// Down Arrow Icon
icon: const Icon(Icons.keyboard_arrow_down),
// Array list of items
items: items.map((String items) {
return DropdownMenuItem(
value: items,
child: SizedBox(
height: 15,
width: 120.0, // for example
child: Text(items,
style: const TextStyle(
fontSize: 13.0,
fontWeight: FontWeight.w700),
textAlign: TextAlign.center),
),
);
}).toList(),
// After selecting the desired option,it will
// change button value to selected value
onChanged: (String? newValue) {
setState(
() {
dropdownValueMembers = newValue!;
},
);
},
),
),
),
],
),
),
const SizedBox(
height: 25,
),
Row(
children: [
Padding(
padding: const EdgeInsets.only(left: 20),
child: Text('Which child'),
),
Padding(
padding:
const EdgeInsets.only(left: 100, right: 0, top: 20),
child: Container(
height: 30,
decoration: BoxDecoration(
boxShadow: const <BoxShadow>[
//apply shadow on Dropdown button
BoxShadow(
color: Color.fromRGBO(
0, 0, 0, 0.37), //shadow for button
blurRadius: 5) //blur radius of shadow
],
color: Colors.white,
borderRadius: BorderRadius.circular(15),
),
child: DropdownButton(
underline: Container(),
borderRadius: BorderRadius.circular(20),
// Initial Value
value: dropdownValueNumber,
// Down Arrow Icon
icon: const Icon(Icons.keyboard_arrow_down),
// Array list of items
items: number.map((String number) {
return DropdownMenuItem(
value: number,
child: SizedBox(
height: 17,
width: 120.0, // for example
child: Text(number,
style: const TextStyle(
fontSize: 13.0,
fontWeight: FontWeight.w700),
textAlign: TextAlign.center),
),
);
}).toList(),
// After selecting the desired option,it will
// change button value to selected value
onChanged: (String? newNumber) {
setState(
() {
dropdownValueNumber = newNumber!;
},
);
},
),
),
),
],
),
const SizedBox(
height: 60,
),
Padding(
padding: const EdgeInsets.only(bottom: 0.0, top: 150),
child: SizedBox(
width: 160.0,
height: 35.0,
child: ElevatedButton(
style: ButtonStyle(
shape:
MaterialStateProperty.all<RoundedRectangleBorder>(
RoundedRectangleBorder(
borderRadius: BorderRadius.circular(18.0),
side: const BorderSide(
color: Colors.blueAccent,
),
),
),
),
onPressed: () {
_saveData(dropdownValueMembers);
_saveDataNumbers(dropdownValueNumber);
},
child: const Text('next')),
),
),
],
),
),
),
);
}
}
如何解决这一问题，并使用共享首选项保存2个或更多数据？