How to use conditional statement within onTap - dart

Question

I have a problem regarding if statement in dart, I want the user to tap the city to go to a new screen. this code work perfectly fine
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));
}
}
Since I have a long list of cities and the previous code will make my code very long so I had to change my code. However, I faced some errors with if statements, here is what I did so far.
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
},
);
}
)
);
}
}

Answer 1

for example, when I press Toronto it will take me to LondonUniversitySection()
That is because in your if statements, you check whether your list contains Toronto/London and not if currently pressed one is Toronto/London. Changing litems.contains("x") to litems[index] == "x" will do the trick. Here's edited fragment:
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()));
}
},
);
Also, I recommend using a switch or else-if for that, not a bunch of ifs.

Answer 2

Try onTap: litems.contains("Totonto")?
Navigator.push( ctxt, MaterialPageRoute( builder: (ctxt) => TorontoUniversitySection() ), )
: null

Answer 3

class _RegisterBodyState extends State<RegisterBody> {
FocusNode myFocusNode = new FocusNode();
FocusNode myFocusNode2 = new FocusNode();
void initState() {
super.initState();
myFocusNode = FocusNode();
myFocusNode2 = FocusNode();
}
#override
void dispose() {
// Clean up the focus node when the Form is disposed.
myFocusNode.dispose();
myFocusNode2.dispose();
super.dispose();
}
Color color;
#override
Widget build(BuildContext context) {
return Center(
child: SingleChildScrollView(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Text(
"Register",
style: TextStyle(
color: Theme.of(context).primaryColor,
fontSize: 70.0,
fontWeight: FontWeight.bold,
),
),
Form(
child: Column(
children: [
TextFormField(
onTap: () {
setState(() {
color = Colors.red;
});
},
autofocus: true,
focusNode: myFocusNode,
decoration: InputDecoration(
icon: Icon(
Icons.supervised_user_circle,
size: 40.0,
),
labelText: "User Name",
labelStyle: TextStyle(
color:
myFocusNode.hasFocus ?color : Colors.yellow),
),
),
TextFormField(
focusNode: myFocusNode2,
onTap: () {
setState(() {
color = Colors.black;
});
},
autofocus: false,
decoration: InputDecoration(
icon: Icon(
Icons.supervised_user_circle,
size: 40.0,
),
labelText: "User Name",
labelStyle: TextStyle(
color: myFocusNode2.hasFocus ? color : Colors.teal,
),
),
),
],
))
],
),
),
);
}
}