我开始使用DropdownButton小部件,并创建了城市列表。当我在列表中选择我最喜欢的城市时,我想看到AlertDialog,但它无法工作。这是代码:
import 'package:flutter/material.dart';
import './func.dart';
class ChooseCity extends StatefulWidget {
@override
State<StatefulWidget> createState() {
return ChooseCityState();
}
}
class ChooseCityState extends State<ChooseCity> {
var cities = ["Ankara", "İzmir", "İstanbul", "Edirne", "Antalya"];
String choosenCity = "Edirne";
@override
Widget build(BuildContext context) {
return Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
DropdownButton<String>(
items: cities.map((String city) {
return DropdownMenuItem<String>(
child: Text(city),
value: city,
);
}).toList(),
value: choosenCity,
onChanged: (String choosen) {
setState(() {
choosenCity = choosen;});
choosen=="Antalya" ?
AlertDialog(
title:Text("ATTENTION"),
content: Text("You chose the best place!!"),
actions: [
FlatButton(child: Text("I see,I agree"),onPressed: ()=>{},)
],
)
: Text("go on");
},
),
SizedBox(
height: 60,
),
Text(
" You choosed :" + choosenCity,
textAlign: TextAlign.center,
),
],
);
}
}
看起来不像我想要的。当我选择“ Antalya”时,我想看到AlertDialog。错误在哪里?我应该在哪里放布尔函数?我试图将此bool函数从setState函数中移出,但不是我想要的。
如果要显示警报对话框,则应使用'showDialog',然后在其生成器中使用警报对话框。
喜欢这个
class ChooseCity extends StatefulWidget {
@override
State<StatefulWidget> createState() {
return ChooseCityState();
}
}
class ChooseCityState extends State<ChooseCity> {
var cities = ["Ankara", "İzmir", "İstanbul", "Edirne", "Antalya"];
String chosenCity = "Edirne";
@override
Widget build(BuildContext context) {
return Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
DropdownButton<String>(
items: cities.map((String city) {
return DropdownMenuItem<String>(
child: Text(city),
value: city,
);
}).toList(),
value: chosenCity,
onChanged: (String choosen) {
chosenCity = choosen;
showAlertDialog();
setState(() {});
},
),
SizedBox(
height: 60,
),
Text(
" You choosed :" + chosenCity,
textAlign: TextAlign.center,
),
],
);
}
showAlertDialog() {
showDialog(
context: context,
builder: (context) {
return AlertDialog(
title: Text("ATTENTION"),
content: Text("You chose the best place!!"),
actions: [
FlatButton(
child: Text("I see,I agree"),
onPressed: () => {},
)
],
);
},
);
}
}