Dropdownbutton value in flutter not changing during onchange event - flutter

Question

I am new to using a Dropdownbutton but I copied this code from a material example and the value is not changing when I pick a different category. Im not sure whats going on but the value changes internally when I debug but the displayed text stays at the default setting which is "Choose a goal category".
DropdownButton<String>(
value: dropdownValue,
icon: Icon(Icons.check_circle_outline),
iconSize: 24,
elevation: 16,
style: TextStyle(
color: Colors.blue[300]
),
underline: Container(
height: 2,
color: Colors.blue[300],
),
onChanged: (String newValue) {
setState(() {
dropdownValue = newValue;
updateCategory(newValue);
});
},
items: <String>['Choose a goal category', 'Financial', 'Physical', 'Family', 'Mental', 'Social', 'Spiritual', 'Personal']
.map<DropdownMenuItem<String>>((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
})
.toList(),
),

Answer 1

Replace this.
items : <String>['Choose a goal category', 'Financial', 'Physical', 'Family', 'Mental', 'Social', 'Spiritual', 'Personal']
.map((String dropDownStringItem){
return DropdownMenuItem<String>{
value : dropDownStringItem,
...
}
}).toList(),
I hope to help you

Answer 2

Step 1: declare String dropdownValue; do not set value
Step 2: use hint and set to Text('Choose a goal category')
Step 3: items remove string "Choose a goal category"
code snippet
String dropdownValue;
...
DropdownButton<String>(
hint: Text('Choose a goal category'),
value: dropdownValue,
icon: Icon(Icons.check_circle_outline),
iconSize: 24,
elevation: 16,
style: TextStyle(color: Colors.deepPurple),
underline: Container(
height: 2,
color: Colors.blue[300],
),
onChanged: (String newValue) {
setState(() {
dropdownValue = newValue;
});
},
items: <String>[
'Financial', 'Physical', 'Family', 'Mental', 'Social', 'Spiritual', 'Personal'
].map<DropdownMenuItem<String>>((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
}).toList(),
),
full code
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
/// This Widget is the main application widget.
class MyApp extends StatelessWidget {
static const String _title = 'Flutter Code Sample';
#override
Widget build(BuildContext context) {
return MaterialApp(
title: _title,
home: Scaffold(
appBar: AppBar(title: const Text(_title)),
body: MyStatefulWidget(),
),
);
}
}
class MyStatefulWidget extends StatefulWidget {
MyStatefulWidget({Key key}) : super(key: key);
#override
_MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
String dropdownValue;
#override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: <Widget>[
Center(
child: DropdownButton<String>(
//isDense: true,
hint: Text('Choose a goal category'),
value: dropdownValue,
icon: Icon(Icons.check_circle_outline),
iconSize: 24,
elevation: 16,
style: TextStyle(color: Colors.deepPurple),
underline: Container(
height: 2,
color: Colors.blue[300],
),
onChanged: (String newValue) {
setState(() {
dropdownValue = newValue;
});
},
items: <String>[
'Financial', 'Physical', 'Family', 'Mental', 'Social', 'Spiritual', 'Personal'
].map<DropdownMenuItem<String>>((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
}).toList(),
),
),
],
),
);
}
}