我正在开发一个外语应用程序。我的申请中有多项选择测试题，但在我完成测试后，出现此错误。不知道有没有人知道这个错误的解决方法。
EXCEPTION : 'package:flutter/src/widgets/framework.dart': Failed assertion: line 4263 pos 12: '_debugLifecycleState != _ElementLifecycle.defunct': is not true.
我的代码
class LoadJson extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: FutureBuilder(
future: DefaultAssetBundle.of(context)
.loadString("lib/quiz/questions.json"),
builder: (context, snapshot) {
List mydata = json.decode(snapshot.data.toString());
if (mydata == null) {
return Center(
child: Text("asldöasid"),
);
} else {
return SorularinOlacagiPage(mydata: mydata);
}
},
),
);
}
}
class SorularinOlacagiPage extends StatefulWidget {
final mydata;
const SorularinOlacagiPage({Key key, this.mydata}) : super(key: key);
@override
_SorularinOlacagiPageState createState() =>
_SorularinOlacagiPageState(mydata: mydata);
}
class _SorularinOlacagiPageState extends State<SorularinOlacagiPage>
with SingleTickerProviderStateMixin {
List<QuestionsModel> _myQuestions = new List<QuestionsModel>();
List mydata;
_SorularinOlacagiPageState({this.mydata});
Color colortoShow = Colors.indigo;
Color right = Colors.green;
Color wrong = Colors.red;
int index = 0;
int i = 1;
int marks = 0;
bool disableAnswer = false;
int j = 1;
int timer = 30;
String showTimer = "30";
var random_array;
Animation animation;
AnimationController animationController;
double beginAnim = 0.0;
double endAnim = 1.0;
Map<String, Color> btnColor = {
"a": Colors.indigoAccent,
"b": Colors.indigoAccent,
"c": Colors.indigoAccent,
"d": Colors.indigoAccent
};
bool cancelTimer = false;
genrandomarray() {
var distinctIds = [];
var rand = new Random();
for (int i = 0;;) {
distinctIds.add(rand.nextInt(20));
random_array = distinctIds.toSet().toList();
if (random_array.length < 20) {
continue;
} else {
break;
}
}
print(random_array);
}
//initstate
@override
void initState() {
// startTimer();
genrandomarray();
super.initState();
_myQuestions = getQuestions();
animationController =
AnimationController(duration: const Duration(seconds: 8), vsync: this);
animation =
Tween(begin: beginAnim, end: endAnim).animate(animationController)
..addListener(() {
setState(() {});
});
startAnim();
animationController.addStatusListener((status) {
if (status == AnimationStatus.completed) {
if (j < 20) {
j++;
resetAnim();
startAnim();
} else {
Navigator.of(context).pushReplacement(MaterialPageRoute(
builder: (context) => TrueFalseSSonucSayfasi(marks: marks)));
}
}
});
}
startAnim() {
animationController.forward();
}
resetAnim() {
animationController.reset();
}
stopAnim() {
animationController.stop();
}
@override
void setState(fn) {
if (mounted) {
super.setState(fn);
}
}
/* void startTimer() async {
const oneSec = Duration(seconds: 1);
Timer.periodic(oneSec, (Timer t) {
setState(() {
if (timer < 1) {
t.cancel();
nextQuestion();
} else if (cancelTimer == true) {
t.cancel();
} else {
timer = timer - 1;
}
showTimer = timer.toString();
});
});
}*/
void nextQuestion() {
if (j < 20) {
i = random_array[j];
j++;
resetAnim();
startAnim();
} else {
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (context) => TrueFalseSSonucSayfasi(
marks: marks,
)));
}
btnColor["a"] = Colors.indigoAccent;
btnColor["b"] = Colors.indigoAccent;
btnColor["c"] = Colors.indigoAccent;
btnColor["d"] = Colors.indigoAccent;
disableAnswer = false;
}
void checkAnswer(String k) {
//Sorular -0 şıklar-1 cevaplar -1 =>index numarları
if (mydata[2][i.toString()] == mydata[1][i.toString()][k]) {
//answer is correct
marks = marks + 5;
colortoShow = right;
} else {
//answer is wrong
colortoShow = wrong;
}
setState(() {
cancelTimer = true;
btnColor[k] = colortoShow;
disableAnswer = true;
});
Timer(Duration(seconds: 2), nextQuestion);
}
Widget choiceButton(String k) {
return Padding(
padding: EdgeInsets.symmetric(vertical: 10, horizontal: 20),
child: MaterialButton(
onPressed: () => checkAnswer(k),
child: Text(
mydata[1][i.toString()][k],
style: TextStyle(color: Colors.white, fontSize: 16),
maxLines: 1,
),
//color: btnColor[k],
color: btnColor[k],
splashColor: Colors.indigo.shade700,
highlightColor: Colors.indigo.shade700,
minWidth: 200,
height: 45,
shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(20)),
),
);
}
@override
Widget build(BuildContext context) {
SystemChrome.setPreferredOrientations(
[DeviceOrientation.portraitDown, DeviceOrientation.portraitUp]);
return WillPopScope(
child: Scaffold(
body: Column(
children: [
Container(
padding: EdgeInsets.only(left: 30, right: 30, top: 20),
child: Row(
crossAxisAlignment: CrossAxisAlignment.end,
children: [
Text(
"${j} / ${_myQuestions.length}",
style: TextStyle(fontSize: 24, fontWeight: FontWeight.w500),
),
Text(
getTranslated(context, "ssoru"),
style: TextStyle(fontSize: 17, fontWeight: FontWeight.w400),
),
Spacer(),
Row(
crossAxisAlignment: CrossAxisAlignment.end,
children: [
Text(
"$marks",
style: TextStyle(
fontSize: 24, fontWeight: FontWeight.w500),
),
SizedBox(
height: 10,
),
Text(
getTranslated(context, "puan"),
style: TextStyle(
fontSize: 17, fontWeight: FontWeight.w400),
),
],
),
],
),
),
Expanded(
flex: 1,
child: Container(
padding: EdgeInsets.all(15),
alignment: Alignment.bottomLeft,
child: Container(
child: LinearProgressIndicator(
value: animation.value,
),
),
),
),
Expanded(
flex: 3,
child: Image.asset(
mydata[0][i.toString()],
),
),
Expanded(
flex: 6,
child: AbsorbPointer(
absorbing: disableAnswer,
child: Container(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
choiceButton("a"),
choiceButton("b"),
choiceButton("c"),
choiceButton("d"),
],
),
),
),
),
],
),
),
onWillPop: () {
return showDialog(
context: context,
builder: (context) => AlertDialog(
title: Text("Test"),
content: Text("Bu Aşamada Geri Dönemezsin"),
actions: [
FlatButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text("Tamam"),
),
],
));
},
);
}
}
例外
════════ Exception caught by animation library ═════════════════════════════════════════════════════
The following assertion was thrown while notifying listeners for AnimationController:
'package:flutter/src/widgets/framework.dart': Failed assertion: line 4263 pos 12: '_debugLifecycleState != _ElementLifecycle.defunct': is not true.