我有一個顯示用戶型別的 DropdownButton。
List<String> items = ['Engineer', 'Technician', 'Sales'];
String? currentSelectedValue;
child: DropdownButtonHideUnderline(
child: Padding(
padding:
const EdgeInsets.symmetric(horizontal: 20.0),
child: DropdownButton<String>(
dropdownColor: Colors.blue.shade100,
isExpanded: true,
hint: Text('Select the user Type'),
onChanged: (newValue) {
setState(() {
currentSelectedValue = newValue;
});
print(currentSelectedValue);
},
items: items.map((String value) {
return DropdownMenuItem(
value: value,
child: Text(
value,
style: TextStyle(color: Colors.black),
),
);
}).toList(),
value: currentSelectedValue,
),
),
),
我可以看到串列，但是當我選擇一個值時，它不會顯示在 DropdownButton 的文本部分。我可以在控制臺中看到列印的選定值。誰能幫我找出錯誤？
uj5u.com熱心網友回復：
確保放在currentSelectedValue構建方法之外。
class Ft extends StatefulWidget {
const Ft({super.key});
@override
State<Ft> createState() => _FtState();
}
class _FtState extends State<Ft> {
List<String> items = ['Engineer', 'Technician', 'Sales'];
String? currentSelectedValue;
@override
Widget build(BuildContext context) {
return Scaffold(
body: DropdownButtonHideUnderline(
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 20.0),
child: DropdownButton<String>(
dropdownColor: Colors.blue.shade100,
isExpanded: true,
hint: Text('Select the user Type'),
onChanged: (newValue) {
setState(() {
currentSelectedValue = newValue;
});
print(currentSelectedValue);
},
items: items.map((String value) {
return DropdownMenuItem(
value: value,
child: Text(
value,
style: TextStyle(color: Colors.black),
),
);
}).toList(),
value: currentSelectedValue,
),
),
),
);
}
}
轉載請註明出處，本文鏈接：https://www.uj5u.com/qukuanlian/526470.html
標籤：扑下拉按钮