我对 dart 中的 if 语句有疑问,我希望用户点击城市转到新屏幕。这段代码工作得很好
class citySec extends StatelessWidget {
Widget getListView(BuildContext context) {
var listView = ListView(
children: <Widget>[
Text(
"choose ur city:",
textDirection: TextDirection.rtl,
textAlign: TextAlign.center,
),
ListTile(
leading: Icon(Icons.location_city),
title: Text("Toronto ", textDirection: TextDirection.rtl),
onTap: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => TorontoUniversitySection(),
),
);
},
),
],
);
return listView;
}
@override
Widget build(BuildContext context) {
return Scaffold(body: getListView(context));
}
}
由于我有很长的城市列表,而以前的代码会使我的代码很长,所以我不得不更改我的代码。但是,我在 if 语句中遇到了一些错误,这是我目前所做的。
import 'package:flutter/material.dart';
import 'package:rate/screens/firstScreen.dart';
void main() {
runApp(MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Rate',
home: Scaffold(
appBar: AppBar(
title: Text("jgfnjfnj ", textDirection: TextDirection.rtl),
),
body: ListDisplay(),
),
));
}
class ListDisplay extends StatelessWidget {
List<String> litems = ["Toronto","NewYork","London","Riyadh","Dubai","Istanbul"];
@override
Widget build (BuildContext ctxt) {
return new Scaffold(
appBar: AppBar(title: Text("Please Choose your city: ", textDirection: TextDirection.ltr,),
),
body: new ListView.builder
(
itemCount: litems.length,
itemBuilder: (BuildContext ctxt, int index) {
return new ListTile(
leading: Icon(Icons.location_city),
title: Text(litems[index], textDirection: TextDirection.rtl),
onTap: () {
// begin of all IF statements
if (litems.contains("Totonto")){
Navigator.push(
ctxt,
MaterialPageRoute(
builder: (ctxt) => TorontoUniversitySection()
),
);
}
if (litems.contains("London")){
Navigator.push(
ctxt,
MaterialPageRoute(
builder: (ctxt) => LondonUniversitySection()
),
);
}
// end of all If statements
},
);
}
)
);
}
}
最佳答案
for example, when I press Toronto it will take me to LondonUniversitySection()
那是因为在您的 if 语句中,您检查您的列表是否包含 Toronto/London 而不是当前按下的是 Toronto/London。将 litems.contains("x")
更改为 litems[index] == "x"
即可。这是经过编辑的片段:
return new ListTile(
leading: Icon(Icons.location_city),
title: Text(litems[index], textDirection: TextDirection.rtl),
onTap: () {
if (litems[index] == "Toronto") {
Navigator.push(
ctxt,
MaterialPageRoute(builder: (ctxt) => TorontoUniversitySection()),
);
} else if (litems[index] == "London") {
Navigator.push(
ctxt,
MaterialPageRoute(builder: (ctxt) => LondonUniversitySection()));
}
},
);
此外,我建议为此使用 switch
或 else-if
,而不是一堆 ifs。
关于dart - 如何在 onTap 中使用条件语句,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/54348646/