Flutter dropdown onChange implementation. In this post, I will be implementing Flutter dropdown onChange with a proper Flutter code example. I will be explaining everything about Flutter dropdown onChange step by step so you don’t have any queries left when you finish reading this post. So let’s not waste anymore time and start implementing Flutter dropdown onChange in Flutter dropdown button.
What is Flutter Dropdown OnChange?
Flutter dropdown onChange is used to select an option from the list of dropdown items and show it in the Flutter dropdown button. Don’t worry in the next section, I will implement Flutter dropdown onChange using an easy Flutter example so you can have a better idea.
Implementing Flutter Dropdown OnChange(All Steps)
To implement Flutter dropdown onChange, we have to use the on changed constructor of the Flutter dropdown button widget. See the below code:
Step 1
DropdownMenuItem( value: 'Sports', child: Text('Sports', style: TextStyle(fontSize: 15, color: Colors.black45))),
The value constructor of the drop down menu item is like an id of that item. This is the value that is being fetched when we select any item from the dropdown list.
Step 2
String? categoryValue;
In step 1, we have to define a string variable so we can store the value of selected item in it.
Step 3
onChanged: (val) { setState(() { categoryValue = val.toString(); }); }
Step 4
value: categoryValue,
Now we have to pass the string variable to the value constructor. By using this, the selected value will be shown in the Flutter dropdown button.
Custom Flutter Dropdown Button Design Source Code
import 'package:flutter/material.dart'; void main() { runApp(MyApp()); } class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( debugShowCheckedModeBanner: false, home: Homepage(), ); } } class Homepage extends StatefulWidget { @override State<Homepage> createState() => _HomepageState(); } class _HomepageState extends State<Homepage> { String? categoryValue; @override Widget build(BuildContext context) { return SafeArea( child: Scaffold( body: Center( child: Padding( padding: EdgeInsets.all(20), child: Container( padding: EdgeInsets.symmetric(horizontal: 20, vertical: 5), decoration: BoxDecoration( borderRadius: BorderRadius.circular(50).copyWith( bottomRight: Radius.circular(0), topLeft: Radius.circular(0)), color: Colors.green.shade100), child: DropdownButtonHideUnderline( child: DropdownButton( iconSize: 30, borderRadius: BorderRadius.circular(20) .copyWith(topLeft: Radius.circular(0)), isExpanded: true, hint: Text('Select any item', style: TextStyle(fontSize: 15)), value: categoryValue, items: [ DropdownMenuItem( value: 'Sports', child: Text('Sports', style: TextStyle(fontSize: 15, color: Colors.black45))), DropdownMenuItem( value: 'Tech', child: Text('Tech', style: TextStyle(fontSize: 15, color: Colors.black45))), ], onChanged: (val) { setState(() { categoryValue = val.toString(); }); }), ), ), )))); } }
Conclusion
In conclusion, now you have a practical understanding of how Flutter dropdown onChange works. I would love to hear your feedback regarding this post. I would also want you to visit my other posts on Flutter app development, Flutter widgets and many more. That’s all for this post. Thanks for reading.