Flutter sharedPreferences initialization - flutter

Question

i want to initialize my sharedPref object before app loading.I tried init func etc. but always on the secreen appears "Instance of Future" text then my sharedPref object initialization end then getStringList method is executed properly.I mean i don't want to see "Instance of Future".What should i do?
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
void main() {
WidgetsFlutterBinding.ensureInitialized();
_MyHomePageState().createSharedObject();
runApp(
MyApp(),
);
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
_MyHomePageState().createSharedObject();
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
String baslik, mesaj;
List<String> kaydedilenNotlar = [];
List<String> kaydedilenBasliklar = [];
List<String> deneme = [];
SharedPreferences sharedPreferences;
Future createSharedObject() async {
sharedPreferences = await SharedPreferences.getInstance();
}
#override
Widget build(BuildContext context) {
return DefaultTabController(
length: 3,
child: Scaffold(
floatingActionButton: FloatingActionButton(
child: Icon(Icons.add),
onPressed: () {
showDialog(
context: context,
builder: (context) {
return AlertDialog(
backgroundColor: Colors.yellowAccent[100],
title: Text(
"Yeni Not",
textAlign: TextAlign.center,
),
content: Container(
height: 250,
child: Column(
children: [
Expanded(
child: TextField(
onChanged: (value) {
setState(() {
baslik = value;
});
},
decoration: InputDecoration(
border: OutlineInputBorder(),
hintText: "Başlık",
hintStyle: TextStyle(
color: Colors.black,
fontStyle: FontStyle.italic),
),
),
),
TextField(
onChanged: (value) {
setState(() {
mesaj = value;
});
},
maxLines: 5,
decoration: InputDecoration(
border: OutlineInputBorder(),
hintText: "Not",
),
),
TextButton(
onPressed: () async {
kaydedilenNotlar.add(mesaj);
kaydedilenBasliklar.add(baslik);
sharedPreferences =
await SharedPreferences.getInstance();
/* sharedPreferences.setStringList(
"not", kaydedilenNotlar);
sharedPreferences.setStringList(
"baslik", kaydedilenBasliklar);*/
},
child: Text(
"Kaydet",
style: TextStyle(fontSize: 18),
))
],
),
),
);
});
},
),
appBar: AppBar(
centerTitle: true,
title: Text("AJANDA"),
bottom: TabBar(
tabs: [
Tab(
child: Text("Yapılacak"),
),
Tab(
child: Text("Yapılıyor"),
),
Tab(
child: Text("Yapıldı"),
)
],
),
),
body: TabBarView(
children: [
Center(
child: Text(
"${sharedPreferences == null ? createSharedObject() : sharedPreferences.getStringList("not")}")),
Center(child: Text("2. sayfa")),
Center(child: Text("3. sayfa")),
],
),
),
);
}
}

Answer 1

The reason for this is that your createSharedObject() function is a Future. And in the lines
child: Text("${sharedPreferences == null ? createSharedObject() : sharedPreferences.getStringList("not")}")),
you are using that Future value and not awaiting for it.
So, if you want to await for the actual value, you'll need a FutureBuilder.
FutureBuilder<String>(
future: your_future_function,
builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
if (snapshot.connectionState==ConnectionState.done){
return Text(snapshot.data);
} else {
return Text('Loading');
}
});
I must say I think there are better ways to deal with the loading of values from SharedPreferences, but for the sake of simplicity, the solution above should work.