How to fix the '!_debugLocked': is not true in flutter? - flutter

Question

I'm new to flutter and I have a problem with the navigation. My app has multiple pages and I can't understand the error and how to fix it.
I searched online and I tried everything that I found on Git / Stack or Google but nothing works.
This is the error : '!_debugLocked': is not true.
This is the code :
This is the first .dart file and the error is when I try to do the Navigator.of .....
import 'package:flutter/material.dart';
class FirstScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.grey[100],
body: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
SizedBox(
height: 320,
),
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'C.R',
style: TextStyle(
fontSize: 120,
fontFamily: 'Membra',
),
)
],
),
SizedBox(
height: 200,
),
FloatingActionButton(
backgroundColor: Colors.white,
child: Image.asset('images/arrow_next.png'),
onPressed: () {
Navigator.of(context).pushNamedAndRemoveUntil(
'/SecondScreen', (Route<dynamic> route) => false);
},
),
],
),
);
}
}
This is the second .dart file where I want to go to from the first file/ page.
import 'package:flutter/material.dart';
import 'NewWidget_Creator.dart';
class SecondScreen extends StatefulWidget {
#override
_SecondScreenState createState() => _SecondScreenState();
}
class _SecondScreenState extends State<SecondScreen> {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
Center(
child: NewWidget(
'Schede',
Navigator.of(context).pushNamedAndRemoveUntil(
'/SecondScreen', (Route<dynamic> route) => false)),
),
NewWidget(
'Orario',
Navigator.of(context).pushNamedAndRemoveUntil(
'/SecondScreen', (Route<dynamic> route) => false)),
NewWidget(
'Pausa',
Navigator.of(context).pushNamedAndRemoveUntil(
'/SecondScreen', (Route<dynamic> route) => false)),
],
),
);
}
}
NewWidgetCreator .dart file :
import 'package:flutter/material.dart';
class NewWidget extends StatelessWidget {
String Name_of_button;
Future<dynamic> send_toNextPage;
NewWidget(this.Name_of_button, this.send_toNextPage);
#override
Widget build(BuildContext context) {
return FlatButton(
onPressed: () {
send_toNextPage;
},
child: Container(
child: Text(
Name_of_button,
textAlign: TextAlign.center,
style: TextStyle(
fontFamily: 'Membra',
fontSize: 50,
),
),
),
);
}
}
Thank you in advance.

Answer 1

Why in NewWidget field send_toNextPage is a Future? Here you have fixed class of NewWidget
class NewWidget extends StatelessWidget {
String buttonName;
String nextPageRoute;
NewWidget(this.buttonName, this.nextPageRoute);
#override
Widget build(BuildContext context) {
return FlatButton(
onPressed: () {
Navigator.of(context).pushNamed(nextPageRoute);
},
child: Container(
child: Text(
buttonName,
textAlign: TextAlign.center,
style: TextStyle(
fontFamily: 'Membra',
fontSize: 50,
),
),
),
);
}
}
This is how to use it in SeconScreen:
class SecondScreen extends StatefulWidget {
#override
_SecondScreenState createState() => _SecondScreenState();
}
class _SecondScreenState extends State<SecondScreen> {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
NewWidget('Schede', '/SecondScreen'),
NewWidget('Orario', '/SecondScreen'),
NewWidget('Pausa', '/SecondScreen'),
],
),
);
}
}
BTW: SecondSreen can be StatelessWidget:
class SecondScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
NewWidget('Schede', '/SecondScreen'),
NewWidget('Orario', '/SecondScreen'),
NewWidget('Pausa', '/SecondScreen'),
],
),
);
}
}