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<code_start>ListView.builder(
itemCount: items.length,
itemBuilder: (context, index) {
return ListTile(
title: Text(items[index]),
);
},
)<code_end>
<topic_end>
<topic_start>
2. Wrap each item in a Dismissible widget
In this step,
give users the ability to swipe an item off the list by using the
Dismissible widget.After the user has swiped away the item,
remove the item from the list and display a snackbar.
In a real app, you might need to perform more complex logic,
such as removing the item from a web service or database.Update the itemBuilder() function to return a Dismissible widget:
<code_start>itemBuilder: (context, index) {
final item = items[index];
return Dismissible(
// Each Dismissible must contain a Key. Keys allow Flutter to
// uniquely identify widgets.
key: Key(item),
// Provide a function that tells the app
// what to do after an item has been swiped away.
onDismissed: (direction) {
// Remove the item from the data source.
setState(() {
items.removeAt(index);
});
// Then show a snackbar.
ScaffoldMessenger.of(context)
.showSnackBar(SnackBar(content: Text('$item dismissed')));
},
child: ListTile(
title: Text(item),
),
);
},<code_end>
<topic_end>
<topic_start>
3. Provide “leave behind” indicators
As it stands,
the app allows users to swipe items off the list, but it doesn’t
give a visual indication of what happens when they do.
To provide a cue that items are removed,
display a “leave behind” indicator as they
swipe the item off the screen. In this case,
the indicator is a red background.To add the indicator,
provide a background parameter to the Dismissible.<topic_end>
<topic_start>
Interactive example
<code_start>import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
// MyApp is a StatefulWidget. This allows updating the state of the
// widget when an item is removed.
class MyApp extends StatefulWidget {
const MyApp({super.key});
@override
MyAppState createState() {
return MyAppState();
}
}
class MyAppState extends State<MyApp> {
final items = List<String>.generate(20, (i) => 'Item ${i + 1}');
@override
Widget build(BuildContext context) {
const title = 'Dismissing Items';
return MaterialApp(
title: title,
theme: ThemeData(
colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
),
home: Scaffold(
appBar: AppBar(
title: const Text(title),
),
body: ListView.builder(
itemCount: items.length,
itemBuilder: (context, index) {
final item = items[index];
return Dismissible(
// Each Dismissible must contain a Key. Keys allow Flutter to
// uniquely identify widgets.
key: Key(item),
// Provide a function that tells the app
// what to do after an item has been swiped away.
onDismissed: (direction) {
// Remove the item from the data source.
setState(() {
items.removeAt(index);
});
// Then show a snackbar.
ScaffoldMessenger.of(context)
.showSnackBar(SnackBar(content: Text('$item dismissed')));
},
// Show a red background as the item is swiped away.
background: Container(color: Colors.red),