Missing concrete of implementation of 'statefulwidget.createstate' and setstate isn't deifned - flutter

Question

I'm totally new in flutter just learned last weeks, and facing two problem here, I'm trying to solve the error, but still can't able to solve it, can anyone help on me? Below is the dart code.
'main.dart'
class Sharer extends StatefulWidget
{
bool _isLoggedIn = false;
Map userProfile;
final facebookLogin = FacebookLogin();
#override
Widget build(BuildContext context)
{
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.amber,
centerTitle: true,
title: Text('Welcome Sharer',
style: TextStyle(
fontSize: 16.0,
color: Colors.black87,
letterSpacing: 1.0,
),
),
),
body:
//Center(
//child: isLoggedin
//?
Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Expanded(
flex: 1,
child: Container(
padding: EdgeInsets.all(20.0),
child: RaisedButton.icon(
onPressed: () async {
final result = await facebookLogin.logIn(['email']);
switch (result.status) {
case FacebookLoginStatus.loggedIn:
final token = result.accessToken.token;
final graphResponse = await http.get('https://graph.facebook.com/v2.12/me?fields=name,picture,email&access_token=${token}');
final profile = JSON.jsonDecode(graphResponse.body);
print(profile);
setState(() {
userProfile = profile;
_isLoggedIn = true;
});
break;
case FacebookLoginStatus.cancelledByUser:
setState(() => _isLoggedIn = false );
break;
case FacebookLoginStatus.error:
setState(() => _isLoggedIn = false );
break;
}
},
icon: Icon(
MyFlutterApp.facebook,
),
label: Text(
'Sharer',
style: TextStyle(
fontFamily: 'MyFlutterApp',
color: Colors.black87,
letterSpacing: 1.0,
),
),
),
),
),
],
),
//),
);
}
}
The error was shown at the class name say 'Missing concrete implementation of statefulwidget.create state' another is 'setstate isn't define', i do not know what are the problem can someone help out?
thanks and regards.

Answer 1

Here is an example of a StatefulWidget implementation
class NameOfYourWidget extends StatefulWidget {
#override
_NameOfYourWidgetState createState() => _NameOfYourWidgetState();
}
class _NameOfYourWidgetState extends State<NameOfYourWidget> {
#override
Widget build(BuildContext context) {
return Container(
);
}
}
For your code , use this instead :
class Shared extends StatefulWidget {
#override
_SharedState createState() => _SharedState();
}
class _SharedState extends State<Shared> {
bool _isLoggedIn = false;
Map userProfile;
final facebookLogin = FacebookLogin();
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.amber,
centerTitle: true,
title: Text(
'Welcome Sharer',
style: TextStyle(
fontSize: 16.0,
color: Colors.black87,
letterSpacing: 1.0,
),
),
),
body:
//Center(
//child: isLoggedin
//?
Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Expanded(
flex: 1,
child: Container(
padding: EdgeInsets.all(20.0),
child: RaisedButton.icon(
onPressed: () async {
final result = await facebookLogin.logIn(['email']);
switch (result.status) {
case FacebookLoginStatus.loggedIn:
final token = result.accessToken.token;
final graphResponse = await http.get(
'https://graph.facebook.com/v2.12/me?fields=name,picture,email&access_token=${token}');
final profile = JSON.jsonDecode(graphResponse.body);
print(profile);
setState(() {
userProfile = profile;
_isLoggedIn = true;
});
break;
case FacebookLoginStatus.cancelledByUser:
setState(() => _isLoggedIn = false);
break;
case FacebookLoginStatus.error:
setState(() => _isLoggedIn = false);
break;
}
},
icon: Icon(
MyFlutterApp.facebook,
),
label: Text(
'Sharer',
style: TextStyle(
fontFamily: 'MyFlutterApp',
color: Colors.black87,
letterSpacing: 1.0,
),
),
),
),
),
],
),
//),
);
}
}
You can learn more about statefulwidget here :
Videos :
Google Developers : How Stateful Widgets Are Used Best
Flutter Tutorial for Beginners- Stateful Widgets
Article : Let's build a simple Stateful Widget in Flutter
Hope it will be helpful