颤振类型 'Future<dynamic>' 不是错误类型的子类型 'Widget'

Question

我在我的flutter项目中添加了一个弹出窗口(alertdialog(，该项目有一个streambuilder。它一开始不起作用，但在使其异步并添加了类似下面的代码之后

await Future.delayed(Duration(milliseconds: 50));

它开始运转良好。此弹出窗口将在数据库中的特定数据更改后出现。后来，我想在我的项目中添加第二个弹出窗口，用于第二个数据库值，不同的是，这个窗口有一个用于用户输入的文本字段，当然还有一个用于此的控制器。当我尝试这个弹出窗口时，效果很好，但在弹出窗口的后面，它给出了

type 'Future<dynamic>' is not a subtype of type 'Widget'

红色/黄色错误背景的错误。这两个弹出窗口之间的区别是，正如我所说，其中一个弹出窗口有用于输入的控制器，我在这里做错了什么？

这是完整的代码：

import 'dart:math';

import 'package:flutter/material.dart';
import 'package:assets_audio_player/assets_audio_player.dart';
import 'package:flutter/scheduler.dart';
import 'numbers.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:sayi_avi/homescreen.dart';


Numbers myNumbers = Numbers();

void main(){
runApp(
GameScreen()
);
}

class GameScreen extends StatefulWidget {
static String id ='gamescreen';

@override
_GameScreenState createState() => _GameScreenState();
}

class _GameScreenState extends State<GameScreen> {
bool _initialized = false;
bool _error = false;
TextEditingController _controller;

void initializeFlutterFire() async {
try {
// Wait for Firebase to initialize and set `_initialized` state to true
await Firebase.initializeApp();
setState(() {
_initialized = true;
});
} catch(e) {
// Set `_error` state to true if Firebase initialization fails
setState(() {
_error = true;
});
}
}

@override
void initState() {
initializeFlutterFire();
super.initState();
getCurrentUser();
_controller = TextEditingController();
}

void dispose() {
_controller.dispose();
super.dispose();
}

final _auth =FirebaseAuth.instance;
User loggedInUser;
final _firestore = FirebaseFirestore.instance;
final String collectionPath = 'users';
String docPath;
var userPath;
DocumentReference userdoc;
var userSnapshot;
String gameResult;
String sendednumber='';
List<dynamic> kullanicisayilari = [];
List<dynamic> rakipsayilari = [];
List<dynamic> sonuc = [];


void getCurrentUser() async{
try{
final user = await _auth.currentUser;
if(user !=null){
loggedInUser =user;
docPath = loggedInUser.uid;
userPath = _firestore.collection(collectionPath);
userdoc = userPath.doc(docPath);
userSnapshot = userdoc.snapshots();
}
}catch(e){
print(e);
}
}

Expanded attachNumber(number,imagenumber){
return Expanded(
child:FlatButton(
onPressed: (){
setState(() {
if(!myNumbers.numberStatus[1]){
myNumbers.buttonValues['numberimage1'] = imagenumber;
myNumbers.numberStatus[1] =true;
myNumbers.decimals[1]=number;
}else if(!myNumbers.numberStatus[2]){
myNumbers.buttonValues['numberimage2'] = imagenumber;
myNumbers.numberStatus[2] =true;
myNumbers.decimals[2]=number;
}else if(!myNumbers.numberStatus[3]){
myNumbers.buttonValues['numberimage3'] = imagenumber;
myNumbers.numberStatus[3] =true;
myNumbers.decimals[3]=number;
}else if(!myNumbers.numberStatus[4]){
myNumbers.buttonValues['numberimage4'] = imagenumber;
myNumbers.numberStatus[4] =true;
myNumbers.decimals[4]=number;
}
});
final assetsAudioPlayer = AssetsAudioPlayer();
assetsAudioPlayer.open(
Audio("assets/audios/click.wav"),
);
},
padding: EdgeInsets.all(0),
child: Image.asset('images/$imagenumber'),
),
);
}

Expanded showDeleteNumbers(statusNumber,number){
return Expanded(
child:FlatButton(
onPressed: (){
setState(() {
myNumbers.decimals[statusNumber]='';
myNumbers.numberStatus[statusNumber] =false;
myNumbers.buttonValues[number] = 'nonumber.png';
});
},
child: Image.asset('images/'+myNumbers.buttonValues['$number']),
),
);
}

Future<void> sendnumber() {
sendednumber="";
for (var numbers in myNumbers.decimals.values){
sendednumber = sendednumber+numbers;
}
Random rnd;
int min = 10000;
int max = 100000;
rnd = new Random();
var r = min + rnd.nextInt(max - min);
kullanicisayilari.add(sendednumber+"|"+r.toString());
return userPath
.doc(docPath)
.update({'atilansayi': kullanicisayilari})
.then((value) => print("User Updated"))
.catchError((error) => print("Failed to update user: $error"));
}
/*
List<Widget> getUserNumbers(){
return
}

*/

Text getUserNumbers(kullanicisayilari){
for(var number in kullanicisayilari){
return Text(number);
};
}

//This one is working fine

_showMaterialDialog(String type) async{
if(type=="win"){
gameResult = "You Win, Gratz!";
}else if(type=="lose"){
gameResult = "You Lose :(";
}
print("buraya girdi");
print(gameResult);
await Future.delayed(Duration(milliseconds: 50));
showDialog (
context: context,
builder: (_) => AlertDialog(
title: Text("Result"),
content: Text(gameResult),
actions: <Widget>[
FlatButton(
child: Text('Close'),
onPressed: () {
Navigator.pushNamed(context, HomeScreen.id);
},
)
],
));
}
//This one is causing errors

_showMaterialDialogNumber() async{
await Future.delayed(Duration(milliseconds: 100));
showDialog (
context: context,
builder: (_) => AlertDialog(
title: Text("Start"),
content: TextField(
controller: _controller,
obscureText: true,
decoration: InputDecoration(
border: OutlineInputBorder(),
labelText: 'Enter your Number',
),
),
actions: <Widget>[
FlatButton(
child: Text('Submit'),
onPressed: () {
Navigator.of(context).pop();
},
)
],
));
}

/*

*/


@override
Widget build(BuildContext context) {
if(_error) {
return Text('error-game', textDirection: TextDirection.ltr);
}

// Show a loader until FlutterFire is initialized
if (!_initialized) {
return Text('Loading', textDirection: TextDirection.ltr);
}
return StreamBuilder<DocumentSnapshot>(
stream: userSnapshot,
builder: (BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
if (snapshot.hasError) {
return Text('Something went wrong');
}

if (snapshot.connectionState == ConnectionState.waiting) {
return Text("Loading");
}
if(snapshot.hasData){
Map<String, dynamic> userDocument  = snapshot.data.data();
print(collectionPath);
print(docPath);
print(snapshot.data);
print(userDocument);
gameResult = userDocument['status'];
//This one works fine
if(gameResult =="win" || gameResult =="lose"){
return _showMaterialDialog(gameResult);
}
//This one causing errors

if(gameResult=="on"){
return _showMaterialDialogNumber();
}
kullanicisayilari = userDocument['atilansayi'];
List<dynamic> kullanicisayilariDuz = [];
List<dynamic> rakipsayilariDuz = [];
List<dynamic> sonuclarDuz = [];
for (var numbers in kullanicisayilari){
var splittedNumber = numbers.split('|');
kullanicisayilariDuz.add(splittedNumber[0]);
}
rakipsayilari = userDocument['rakipsallama'];
sonuc = userDocument['sonuc'];
for (var sonuclar in sonuc){
var splittedSonuc = sonuclar.split('|');
sonuclarDuz.add(splittedSonuc[0]);
}
for (var rakipsayi in rakipsayilari){
var splittedRakipSayi = rakipsayi.split('|');
rakipsayilariDuz.add(splittedRakipSayi[0]);
}
print(myNumbers.decimals);
return MaterialApp(
home:Scaffold(
appBar: AppBar(
backgroundColor: Colors.amberAccent,
title: Text('Sayı Avı Oyun Ekranı'),
),
body:Column(
children: <Widget>[
Expanded(
flex: 80,
child: Row(
children: <Widget>[
Expanded(
flex: 40,
child: Column(
children: <Widget>[
for(var numbers in kullanicisayilariDuz)Text(numbers),
]
),
),
Expanded(
flex: 10,
child: Column(
children: <Widget>[
for(var numbers in sonuclarDuz)Text(numbers),
]
),
),
Expanded(
flex: 50,
child: Column(
children: <Widget>[
for(var numbers in rakipsayilariDuz)Text(numbers),
]
),
),
],
),
),
Expanded(
flex:10,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
showDeleteNumbers(1,'numberimage1'),
showDeleteNumbers(2,'numberimage2'),
showDeleteNumbers(3,'numberimage3'),
showDeleteNumbers(4,'numberimage4'),
Expanded(
child:FlatButton(
onPressed: (){
sendnumber();
},
child: Image.asset('images/send.png'),
),
),
],
),
),
Expanded(
flex: 10,
child: Row(
children: <Widget>[
attachNumber('1','one.png'),
attachNumber('2','two.png'),
attachNumber('3','three.png'),
attachNumber('4','four.png'),
attachNumber('5','five.png'),
attachNumber('6','six.png'),
attachNumber('7','seven.png'),
attachNumber('8','eight.png'),
attachNumber('9','nine.png'),
attachNumber('0','zero.png'),
],
),
),
],
),
),
);
}
},
);
}
}

提前谢谢。

Answer 1

GameScreen的build函数需要返回一个Widget:

Widget build(...) {}

然而，当你显示对话框时，你会：

return _showMaterialDialog();

此对话框函数返回一个不能作为Widget的Future<>。这解释了错误。

我更喜欢显式地声明它们，它们应该在异步函数中返回对话框，如下所示：

Future _showMaterialDialog() async {
...
return showDialog(...);
}

顺便说一句，使用相同的上下文传递到函数的参数中应该更好：

Future _showMaterialDialog(BuildContext context) {
// use the local 'context' to build the dialog
}

最后，为了正确地使用这些对话框，只需显示它们并最终返回一个Widget：

if (...) {
_showMaterialDialog(context);
}
return MaterialApp(...);

而且，如果您允许显示UI的时间，则不需要添加的两个delayed
事实上，由于使用StreamBuilder，用户界面尚未显示，您需要等待使用addPostFrameCallback:刷新主渲染管道

WidgetsBinding.instance.addPostFrameCallback((_) {
_showMaterialDialog(context);
}

附言：请记住Flutter就是所有的小部件，请考虑将您的代码引用到小部件中，以避免只在一个类中做很多事情。