本文介绍了如何使用“提交”按钮浏览问题列表的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有这个颤动的代码（用于测验），我希望将提交按钮移到下一个问题，但是使用SubmitQuestion（）不会激活按钮，也不会包含动画
I have this flutter code (for a quiz) and I would like the submit button to move to the next question, however using the submitQuestion() does not activate the button nor the animation included
import 'dart:async';
import 'package:flutter/material.dart';
import 'dart:io';
var _counter = 0;
var bkgrdColor = Colors.blue[50];
bool isAnswerCorrect1 = (questions[_counter].answers[_ansCounter1] ==
questions[_counter].correctAnswer);
bool isAnswerCorrect2 = (questions[_counter].answers[_ansCounter2] ==
questions[_counter].correctAnswer);
bool isAnswerCorrect3 = (questions[_counter].answers[_ansCounter3] ==
questions[_counter].correctAnswer);
bool isAnswerCorrect4 = (questions[_counter].answers[_ansCounter4] ==
questions[_counter].correctAnswer);
final int _ansCounter1 = 0;
final int _ansCounter2 = 1;
final int _ansCounter3 = 2;
final int _ansCounter4 = 3;
final int ans1Value = 1;
final int ans2Value = 2;
final int ans3Value = 3;
final int ans4Value = 4;
var TIMEOUT = const Duration(seconds: 3);
var ms = const Duration(milliseconds: 1);
List<Question> questions = [
new Question("What is 2+2", ["2", "3", "4", "5"], "4"),
new Question("What is 1+1", ["2", "3", "4", "5"], "2"),
new Question("What is 4+4", ["7", "8", "10", "16"], "8"),
new Question("What is 5+5", ["10", "12", "25", "20"], "10"),
new Question("What is 3+3", ["4", "5", "6", "7"], "6")
];
class Question {
String question;
List<String> answers;
String correctAnswer;
Question(this.question, this.answers, this.correctAnswer);
}
void main() {
runApp(new _questionDisplay());
}
class _questionDisplay extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(home: new QuestDis());
}
}
class QuestDis extends StatefulWidget {
QuestDis({Key key}) : super(key: key);
@override
_QuestDisState createState() => new _QuestDisState();
}
class _QuestDisState extends State<QuestDis> with TickerProviderStateMixin {
AnimationController _controller;
int radioValue = 0;
@override
initState() {
_controller = new AnimationController(
vsync: this,
duration: const Duration(milliseconds: 100),
)..addStatusListener((AnimationStatus status) {
if (status == AnimationStatus.completed) _controller.reverse();
});
super.initState();
}
void handleRadioValueChanged(int value) {
if (radioValue != 0) _controller.forward();
setState(() {
radioValue = value;
print("Radio value is: $radioValue");
switch (radioValue) {
case 1:
bkgrdColor = isAnswerCorrect1 ? Colors.green[100] : Colors.red[100];
break;
case 2:
bkgrdColor = isAnswerCorrect2 ? Colors.green[100] : Colors.red[100];
break;
case 3:
bkgrdColor = isAnswerCorrect3 ? Colors.green[100] : Colors.red[100];
break;
case 4:
bkgrdColor = isAnswerCorrect4 ? Colors.green[100] : Colors.red[100];
break;
}
submitButton();
});
}
submitButton() {
_counter++;
radioValue = 0;
bkgrdColor = Colors.blue[50];
} //nextQuestion() }
Widget build(BuildContext context) {
ThemeData theme = Theme.of(context);
var container = new Container(
child: new Column(
children: [
new Column(
children: [
new Row(
children: [
new Expanded(
child: new Container(
child: new Row(
children: [
new Radio<int>(
value: ans1Value,
groupValue: radioValue,
onChanged: handleRadioValueChanged),
new Text(
"${questions[_counter].answers[_ansCounter1]}")
],
),
),
),
new Expanded(
child: new Container(
child: new Row(children: [
new Radio<int>(
value: ans2Value,
groupValue: radioValue,
onChanged: handleRadioValueChanged),
new Text("${questions[_counter].answers[_ansCounter2]}")
]),
),
),
],
),
],
),
new Column(
children: [
new Column(
children: [
new Row(
children: [
new Expanded(
child: new Container(
child: new Row(
children: [
new Radio<int>(
value: ans3Value,
groupValue: radioValue,
onChanged: handleRadioValueChanged),
new Text(
"${questions[_counter].answers[_ansCounter3]}")
],
),
),
),
new Expanded(
child: new Container(
child: new Row(children: [
new Radio<int>(
value: ans4Value,
groupValue: radioValue,
onChanged: handleRadioValueChanged),
new Text(
"${questions[_counter].answers[_ansCounter4]}")
]),
),
),
],
),
],
),
],
),
],
),
);
return new Scaffold(
appBar: new AppBar(
leading: new IconButton(icon: new Icon(Icons.menu), onPressed: null),
title: new Text('getdata'),
),
body: new Container(
child: new Column(
children: [
new Expanded(
//child: new Container(
child: new Column(
children: <Widget>[
new Expanded(
flex: 3,
child: new Container(
child: new Card(
color: bkgrdColor,
child: new Row(
children: <Widget>[
new Text("${questions[_counter].question}"),
],
),
),
),
),
new Expanded(
flex: 1,
child: new Center(
child: container,
),
),
new AnimatedBuilder(
child: const Text('SUBMIT'),
animation: _controller,
builder: (BuildContext context, Widget child) {
return new RaisedButton(
color: new ColorTween(
begin: theme.primaryColor,
end: theme.disabledColor,
)
.animate(_controller)
.value,
colorBrightness: Brightness.dark,
child: child,
onPressed:
radioValue == 0 ? null : submitButton());
})
],
),
),
],
),
),
);
}
@override
void dispose() {
_controller.dispose();
super.dispose();
}
}
我的方法是否错误/如何解决？
Is my approach wrong/how do I address this?
推荐答案
您应将 submitButton（）替换为 onPressed 参数中的> submitButton 。您希望 onPressed 是 VoidCallback 而不是 null （调用 submitButton ）的结果。
You should replace submitButton() with submitButton in your onPressed argument. You want onPressed to be a VoidCallback rather than null (the result of calling submitButton).
此外，修改您的SubmitButton方法以调用 setState ，例如
Also, modify your submitButton method to call setState, e.g.
setState(() {
_counter++;
radioValue = 0;
bkgrdColor = Colors.blue[50];
});
您需要始终调用 setState（）当您修改州的成员时，否则Flutter将不知道如何重建您。
You need to always call setState() when you modify members of your State because otherwise Flutter won't know to rebuild you.
这篇关于如何使用“提交”按钮浏览问题列表的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！