I used shared preference dependency to my project.At the initially open app dropdown value must be 'howmany' but when select any other value and click next button and close application from mobile recents and user when reopen again then should display the value selected value by the user.
Ex:- At the initially user open app then dropdown value must be 'howmany' and he select "three" and click next button after close the app and remove from recents apps. Later when he reopen the app must display dropdown value is "three"
images initial value
And according to this scenario, I tried to code but then shows these errors. 1st error
2nd error
MY code
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
class FamilyDetailsScreen extends StatefulWidget {
@override
State<FamilyDetailsScreen> createState() => _FamilyDetailsScreenState();
}
class _FamilyDetailsScreenState extends State<FamilyDetailsScreen> {
// dropdown buttons
late String dropdownValueMembersShared;
// List of items in our dropdown menu
var items = ['howmany', 'one', 'two', 'three ', 'four ', '5 or more'];
void initState() {
super.initState();
checkValueMembers();
}
//IF "dropdownValueMembers" is empty pass "howmany" word as a initial value if al ready selected then pass the shared preference value
checkValueMembers() {
if (dropdownValueMembersShared != false) {
// Initial Selected Value Members
String dropdownValueMembers = 'howmany';
} else {
String dropdownValueMembers = dropdownValueMembersShared;
}
}
_saveData(String dropdownValueMembersShared) async {
SharedPreferences sharedPreferences = await SharedPreferences.getInstance();
sharedPreferences.setString("data", dropdownValueMembersShared);
}
@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,
),
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;
},
child: const Text('next')),
),
),
],
),
),
),
);
}
}
How to solve these errors and How to adding sharedpreference to this code help me......
CodePudding user response：
try this
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();
}
//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(() {});
}
@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,
),
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);
},
child: const Text('next')),
),
),
],
),
),
),
);
}
CodePudding user response：
In your checkValueMembers method you should have it check to be
dropdownValueMembersShared == ''
You currently check and assume it is a boolean type when it is a string. You also need to only set it to howmany when it's empty, and then default to the value if there is one, which your current statement does not do.