how to create conditional statement with string in Flutter? - string

Question

I am trying to create an app with a flutter on android studio 3.5.2, everything is fully updated,
the concept is this, There is a text field, and a Submit button,
and within the submit button, three strings/text needs to be valid to get inside,
if somebody typed a word that won't match it will show, no words exist,
for example,
Strings - Philippines, Dubai, Japan
if {
textfield does not match string,
Show text hint - Does not match data,
}
Else
{
Welcome from "string"
}
I'm still new, and I know this is not the exact code, but I hope somebody can help me translate this for flutter code, thank you to whoever will help.

Answer 1

Try this,
import 'package:flutter/material.dart';
class Question1 extends StatefulWidget {
#override
State<StatefulWidget> createState() {
return _Question1State();
}
}
class _Question1State extends State<Question1> {
TextEditingController _textController = TextEditingController();
String infoText = '';
List<String> countryList = [
'philippines',
'dubai',
'japan',
];
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: Padding(
padding: EdgeInsets.all(20.0),
child: Column(
children: <Widget>[
TextField(
controller: _textController,
decoration: InputDecoration(
hintText: 'Enter Country',
),
),
SizedBox(
height: 25.0,
),
FlatButton(
onPressed: () {
_validateUserInput(_textController.text);
},
child: Text('Submit'),
color: Colors.blue,
),
SizedBox(
height: 25.0,
),
Text(
infoText,
style: TextStyle(color: Colors.red),
),
],
),
),
);
}
_validateUserInput(String input) {
if (!countryList.contains(input.toLowerCase())) {
setState(() {
infoText = 'Does not match data';
});
} else {
setState(() {
infoText = 'Welcome from $input';
});
}
}
}

Answer 2

Declare a list of string you need to match,
List<String> mList = ['philippines', 'dubai', 'japan'];
then match your textfiled string like this,
var myStr = 'dubai';//or your textFieldController.text
if (mList.contains(myStr)) {
print('Welcome from ${myStr}');
} else {
print('Does not match data');
}
Or as #Rahul Patel Suggested in his answer you do it by ternary operator,
mList.contains(myStr) ? print('Welcome from ${myStr}') : print('Does not match data');

Answer 3

You can use a ternary operator to solve this issue, it is a simple condensed syntax for a conditional if else. The syntax is as follows:
(some conditional || or other conditional && required conditional)?someMethodToHandleSuccess:someMethodToHandleFailure
The (conditional)?ifTrue:ifFalse is the general syntax. Hope this helps!