Flutter – Implement DropdownButton Inside an AlertDialog
Last Updated :
16 Oct, 2023
DropdownButton widget is used to create a dropdown menu that allows users to select one option from a list of available choices. It’s a common user interface element for selecting items from a list. An Alert Dialog is a useful way to grab users’ attention. Here we can see how to implement an AlertDialog, and then we are going to implement a DropdownButton inside the AlertDialog. In this article, we will implement the AertDialog and DropdownButton, A sample video is given below to get an idea about what we are going to do in this article.
Required Tools
To build this app, you need the following items installed on your machine:
- Visual Studio Code / Android Studio
- Android Emulator / iOS Simulator / Physical Device device.
- Flutter Installed
- Flutter plugin for VS Code / Android Studio.
Step By Step Implementations
Step 1: Create a New Project in Android Studio
To set up Flutter Development on Android Studio please refer to Android Studio Setup for Flutter Development, and then create a new project in Android Studio please refer to Creating a Simple Application in Flutter.
Step 2: Import the Package
First of all import material.dart file.
import 'package:flutter/material.dart';
Step 3: Execute the main Method
Here the execution of our app starts.
Dart
void main() {
runApp(MyApp());
}
|
Step 4: Create MyApp Class
In this class we are going to implement the MaterialApp , here we are also set the Theme of our App.
Dart
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
theme: ThemeData(
primarySwatch: Colors.green,
),
home: DropDownAlertDialog(),
);
}
}
|
Step 5: Create DropDownAlertDialog Class
In this class we are going to Implement the DropdownButton widget inside an Alert Dialog that help to create a dropdown menu where users can select one option from a list of available options and the selected option is displayed in the debug console window .Comments are added for better understanding.
// Method for implementing an DropDownButton inside an AlertDialog
void showMyDialog(BuildContext context) {
// Creating an Dialog
showDialog(
context: context,
builder: (BuildContext context) {
// Use a nullable type
String? selectedItem = 'Option 1';
// Creating a list of avaliable options
List<String> items = ['Option 1', 'Option 2', 'Option 3', 'Option 4'];
return AlertDialog(
title: Text('Select an option'),
content: Column(
mainAxisSize: MainAxisSize.min,
children: [
DropdownButton<String>(
value: selectedItem,
items: items.map((String item) {
return DropdownMenuItem<String>(
value: item,
child: Text(item),
);
}).toList(),
onChanged: (String? newValue) {
// Use a nullable type for onChanged
if (newValue != null) {
selectedItem = newValue;
}
},
),
],
),
actions: [
ElevatedButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text('Cancel'),
),
ElevatedButton(
onPressed: () {
// Handle the selected item here
if (selectedItem != null) {
print('Selected item: $selectedItem');
}
Navigator.of(context).pop();
},
child: Text('OK'),
),
],
);
},
);
}
Dart
class DropDownAlertDialog extends StatelessWidget {
const DropDownAlertDialog({super.key});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Dropdown in AlertDialog'),
),
body: Center(
child: ElevatedButton(
onPressed: () {
showMyDialog(context);
},
child: Text('Show AlertDialog'),
),
),
);
}
void showMyDialog(BuildContext context) {
showDialog(
context: context,
builder: (BuildContext context) {
String? selectedItem = 'Option 1';
List<String> items = ['Option 1', 'Option 2', 'Option 3', 'Option 4'];
return AlertDialog(
title: Text('Select an option'),
content: Column(
mainAxisSize: MainAxisSize.min,
children: [
DropdownButton<String>(
value: selectedItem,
items: items.map((String item) {
return DropdownMenuItem<String>(
value: item,
child: Text(item),
);
}).toList(),
onChanged: (String? newValue) {
if (newValue != null) {
selectedItem = newValue;
}
},
),
],
),
actions: [
ElevatedButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text('Cancel'),
),
ElevatedButton(
onPressed: () {
if (selectedItem != null) {
print('Selected item: $selectedItem');
}
Navigator.of(context).pop();
},
child: Text('OK'),
),
],
);
},
);
}
}
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Here is the full Code of main.dart file
Dart
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
theme: ThemeData(
primarySwatch: Colors.green,
),
home: DropDownAlertDialog(),
);
}
}
class DropDownAlertDialog extends StatelessWidget {
const DropDownAlertDialog({super.key});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Dropdown in AlertDialog'),
),
body: Center(
child: ElevatedButton(
onPressed: () {
showMyDialog(context);
},
child: Text('Show AlertDialog'),
),
),
);
}
void showMyDialog(BuildContext context) {
showDialog(
context: context,
builder: (BuildContext context) {
String? selectedItem = 'Option 1';
List<String> items = ['Option 1', 'Option 2', 'Option 3', 'Option 4'];
return AlertDialog(
title: Text('Select an option'),
content: Column(
mainAxisSize: MainAxisSize.min,
children: [
DropdownButton<String>(
value: selectedItem,
items: items.map((String item) {
return DropdownMenuItem<String>(
value: item,
child: Text(item),
);
}).toList(),
onChanged: (String? newValue) {
if (newValue != null) {
selectedItem = newValue;
}
},
),
],
),
actions: [
ElevatedButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text('Cancel'),
),
ElevatedButton(
onPressed: () {
if (selectedItem != null) {
print('Selected item: $selectedItem');
}
Navigator.of(context).pop();
},
child: Text('OK'),
),
],
);
},
);
}
}
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Output:
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