Button problem in Flutter, how can I solve it? - flutter

Question

I have a problem with a button in Flutter, as pressing it does not generate any events, and I can't think of any way to fix it.
CODE:
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:fbutton/fbutton.dart';
import 'package:quiz_cisco1_0/quizprincipal.dart';
void main() => runApp(MyAppState());
class MyAppState extends StatelessWidget{
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: "Cisco Quiz",
home: Scaffold(
extendBodyBehindAppBar: true,
body: SafeArea(
child: Column(
children: [
Center(
child: Image.asset("assets/cisco_logo.png", width: 200, height: 200,),
),
Center(
child: Image.asset("assets/quizz.png", width: 200, height: 200,),
),
Text("La App Perfecta para prepararte", style: TextStyle(fontSize: 19.0,fontWeight: FontWeight.bold)),
Text("en Cisco CCNA 1,2 y 3", style: TextStyle(fontSize: 19.0, fontWeight: FontWeight.bold),),
SizedBox(height: 85.0),
FButton(
width: 185,
height: 60,
alignment: Alignment.center,
text: "Empezar",
style: TextStyle(color: Colors.white, fontWeight: FontWeight.bold,fontSize: 20.0),
color: Colors.blue,
onPressed: (){
Navigator.push(context,
MaterialPageRoute(builder:(context) => MyAppsds()));
},
clickEffect: true,
corner: FCorner(
leftBottomCorner: 40,
leftTopCorner: 6,
rightTopCorner: 40,
rightBottomCorner: 6
),
),
],
),
),
),
);
}
}
CODE:
import 'package:flutter/material.dart';
import './quiz.dart';
import './result.dart';
import 'main.dart';
class MyAppsds extends StatefulWidget{
_MyAppState createState() {
return _MyAppState();
}
}
class _MyAppState extends State<MyAppsds> {
final _questions = const [
{
'questionText': '1. Un router con un sistema operativo válido contiene un archivo de configuración almacenado en la NVRAM. El archivo de configuración tiene una contraseña secreta de habilitación pero no una contraseña de consola. Cuando el router se inicie, ¿qué modo se mostrará?',
'answers': [
{'text': 'Modo de configuración global', 'score': -2},
{'text': 'Modo de ejecución privilegiado', 'score': -2},
{'text': 'Modo EXEC usuario', 'score': 10},
{'text': 'Modo de configuración', 'score': -2},
],
},
{
'questionText': ' 2.¿Por qué un switch de Capa 2 necesitaría una dirección IP?',
'answers': [
{'text': 'Para permitir que el switch envíe tramas de broadcast a los PCs conectados', 'score': -2},
{'text': 'Para permitir que el switch funcione como una puerta de enlace por defecto', 'score': -2},
{'text': 'Para permitir que el switch reciba tramas de los PCs conectados', 'score': -2},
{
'text':
'Para permitir que el switch sea administrado a distancia',
'score': 10
},
],
},
{
'questionText': ' 3.¿Cuál es el SVI por defecto en un switch Cisco?',
'answers': [
{'text': 'VLAN999', 'score': -2},
{'text': 'VLAN1', 'score': 10},
{'text': 'VLAN99', 'score': -2},
{'text': 'VLAN100', 'score': -2},
],
},
{
'questionText': '4.En el comando ‘show running-config’, ¿qué parte de la sintaxis está representada por ‘running-config’?',
'answers': [
{'text': 'Una palabra clave', 'score': 10},
{'text': 'El comando', 'score': -2},
{'text': 'Una variable', 'score': -2},
{'text': 'Un aviso', 'score': -2},
],
},
{
'questionText': '5.¿Qué tipo de tráfico de red requiere QoS?',
'answers': [
{'text': 'Video conferencia', 'score': 10},
{'text': 'Compra en línea', 'score': -2},
{'text': 'Wiki', 'score': -2},
{'text': 'Correo electrónico', 'score': -2},
],
},
{
'questionText': '6.¿En qué capa del modelo OSI se añadiría una dirección lógica durante el encapsulamiento?',
'answers': [
{'text': 'Capa física', 'score': -2},
{'text': 'Capa de enlace de datos', 'score': -2},
{'text': 'Capa de red', 'score': 10},
{'text': 'Capa de transporte', 'score': -2},
],
},
];
var _questionIndex = 0;
var _totalScore = 0;
void _resetQuiz() {
setState(() {
_questionIndex = 0;
_totalScore = 0;
});
}
void _answerQuestion(int score) {
_totalScore += score;
setState(() {
_questionIndex = _questionIndex + 1;
});
print(_questionIndex);
if (_questionIndex < _questions.length) {
print('We have more questions!');
} else {
print('No more questions!');
}
}
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: Text('Quiz Cisco'),
flexibleSpace: Image(
image: AssetImage('assets/banner.jpg'),
fit: BoxFit.cover,
),
backgroundColor: Colors.transparent,
),
body: Padding(
padding: const EdgeInsets.all(30.0),
child: _questionIndex < _questions.length
? Quiz(
answerQuestion: _answerQuestion,
questionIndex: _questionIndex,
questions: _questions,
) //Quiz
: Result(_totalScore, _resetQuiz),
), //Padding
), //Scaffold
debugShowCheckedModeBanner: false,
); //MaterialApp
}
}
error:
Exception caught by gesture
The following assertion was thrown while handling a gesture:
Navigator operation requested with a context that does not include a Navigator.
The context used to push or pop routes from the Navigator must be that of a widget that is a descendant of a Navigator widget.
When the exception was thrown, this was the stack:
#0 Navigator.of. (package:flutter/src/widgets/navigator.dart:2711:9)
#1 Navigator.of (package:flutter/src/widgets/navigator.dart:2718:6)
#2 Navigator.push (package:flutter/src/widgets/navigator.dart:2116:22)
#3 MyAppState.build. (package:quiz_cisco1_0/main.dart:37:29)
#4 _FButton.onPressed (package:fbutton/fbutton.dart:561:23)
...
Handler: "onTap"
Recognizer: TapGestureRecognizer#665d0
debugOwner: GestureDetector
state: possible
won arena
finalPosition: Offset(184.2, 566.6)
finalLocalPosition: Offset(96.7, 6.1)
button: 1
sent tap down

Answer 1

In MyAppState, the context you're using cannot find the MaterialApp (which includes a default Navigator widget). To have a context with the MaterialApp, separate the Scaffold into a different StatelessWidget.
Sample:
FROM
...
home: Scaffold(
...
TO
class HomePage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(...);
}
}
Also, in _MyAppState, you can remove the MaterialApp and just return a Scaffold. In MyAppsds, don't forget to put #override in createState().
I would also suggest to change the name of _MyAppState. Recommended name for State classes would be _<StatefulWidget name>State. (setting it to private is optional)
Sample: _MyAppsdsState