The AnimatedList widget in Flutter is used to create a list that automatically animates changes to its items. It’s particularly useful when you want to add or remove items from a list with smooth animations. In this article, we are going to see how the list is animated when an item is deleted or added to the list. In this article, we are going to implement the AnimatedList widget. A sample video is given below to get an idea about what we are going to do in this article.
Basic Syntax of AnimatedList Widget
AnimatedList(
key: GlobalKey<AnimatedListState>(), // A unique key to identify the list
initialItemCount: itemCount, // The initial number of items in the list
itemBuilder: (BuildContext context, int index, Animation<double> animation) {
// The builder function for creating list items
return YourListItemWidget(item: yourDataList[index], animation: animation);
},
)
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 Implementation
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(
theme: ThemeData(
primarySwatch:
Colors.green, // Set the app's primary theme color to green
),
debugShowCheckedModeBanner: false,
home: MyAnimatedList(),
);
}
} |
Step 5: Create MyAnimatedList Class
In this class we are going to Implement the AnimatedList widget that help to Animated the list when an item is added or removed. This class contains 3 methods :
- _addItem method is used to add a new item to the list.
- _removeItem method is used to remove an item from the list.
- buildItem is a helper method that builds each item in the list. It uses SizeTransition for the animation effect.
Comments are added for better understanding.
AnimatedList(
key: _listKey,
initialItemCount: _items.length,
itemBuilder: (context, index, animation) {
return buildItem(_items[index], animation); // Build each list item
},
),
Dart
class MyAnimatedList extends StatefulWidget {
@override
_MyAnimatedListState createState() => _MyAnimatedListState();
} class _MyAnimatedListState extends State<MyAnimatedList> {
final GlobalKey<AnimatedListState> _listKey = GlobalKey<AnimatedListState>();
List<String> _items = [
'Item 1',
'Item 2',
'Item 3',
'Item 4',
'Item 5',
'Item 6',
'Item 7',
'Item 8',
'Item 9',
'Item 10'
];
void _addItem() {
final newIndex = _items.length; // Calculate the index for the new item
final newItem = 'Item ${newIndex + 1}'; // Create a new item
// Update the underlying data list
setState(() {
_items.add(newItem);
});
// Insert the new item into the AnimatedList
_listKey.currentState!.insertItem(newIndex);
}
void _removeItem(int index) {
final removedItem = _items[index];
// Remove the item from the data list
setState(() {
_items.removeAt(index);
});
// Remove the item from the AnimatedList with animation
_listKey.currentState!.removeItem(
index,
(context, animation) => buildItem(removedItem, animation),
);
}
Widget buildItem(String item, Animation<double> animation) {
return SizeTransition(
sizeFactor: animation,
child: ListTile(
title: Text(item), // Display the item's text
trailing: IconButton(
icon: Icon(Icons.delete), // Display a delete icon
onPressed: () =>
_removeItem(_items.indexOf(item)), // Remove the item when pressed
),
),
);
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('AnimatedList Example'), // Set the app bar title
),
body: AnimatedList(
key: _listKey,
initialItemCount: _items.length,
itemBuilder: (context, index, animation) {
return buildItem(_items[index], animation); // Build each list item
},
),
floatingActionButton: FloatingActionButton(
onPressed: _addItem, // Add a new item when the FAB is pressed
child: Icon(Icons.add), // Display a plus icon
),
);
}
} |
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(
theme: ThemeData(
primarySwatch:
// Set the app's primary
// theme color to green
Colors.green,
),
debugShowCheckedModeBanner: false,
home: MyAnimatedList(),
);
}
} class MyAnimatedList extends StatefulWidget {
@override
_MyAnimatedListState createState() => _MyAnimatedListState();
} class _MyAnimatedListState extends State<MyAnimatedList> {
final GlobalKey<AnimatedListState> _listKey = GlobalKey<AnimatedListState>();
List<String> _items = [
'Item 1',
'Item 2',
'Item 3',
'Item 4',
'Item 5',
'Item 6',
'Item 7',
'Item 8',
'Item 9',
'Item 10'
];
void _addItem() {
final newIndex = _items.length; // Calculate the index for the new item
final newItem = 'Item ${newIndex + 1}'; // Create a new item
// Update the underlying data list
setState(() {
_items.add(newItem);
});
// Insert the new item into the AnimatedList
_listKey.currentState!.insertItem(newIndex);
}
void _removeItem(int index) {
final removedItem = _items[index];
// Remove the item from the data list
setState(() {
_items.removeAt(index);
});
// Remove the item from the AnimatedList with animation
_listKey.currentState!.removeItem(
index,
(context, animation) => buildItem(removedItem, animation),
);
}
Widget buildItem(String item, Animation<double> animation) {
return SizeTransition(
sizeFactor: animation,
child: ListTile(
title: Text(item), // Display the item's text
trailing: IconButton(
icon: Icon(Icons.delete), // Display a delete icon
onPressed: () =>
_removeItem(_items.indexOf(item)), // Remove the item when pressed
),
),
);
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('AnimatedList Example'), // Set the app bar title
),
body: AnimatedList(
key: _listKey,
initialItemCount: _items.length,
itemBuilder: (context, index, animation) {
return buildItem(_items[index], animation); // Build each list item
},
),
floatingActionButton: FloatingActionButton(
onPressed: _addItem, // Add a new item when the FAB is pressed
child: Icon(Icons.add), // Display a plus icon
),
);
}
} |