If You want to create lists that display different types of content. For example, you might be working on a list that display a header followed by a sub items related to the header, followed by another header.
Convert the data source into widgets
ListView.builder(
// Let the ListView know how many items it needs to build.
itemCount: items.length,
// Provide a builder function. This is where the magic happens.
// Convert each item into a widget based on the type of item it is.
itemBuilder: (context, index) {
final item = items[index];
if (item is HeadingItem) {
return ListTile(
title: Text(
item.heading,
style: Theme.of(context).textTheme.headline,
),
);
} else if (item is MessageItem) {
return ListTile(
title: Text(item.sender),
subtitle: Text(item.body),
);
}
},
);main.dart
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
void main() {
runApp(MyApp(
items: List<ListItem>.generate(
100,
(i) => i % 4 == 0
? HeadingItem("Heading $i")
: MessageItem("Sender $i", "Message body $i"),
),
));
}
class MyApp extends StatelessWidget {
final List<ListItem> items;
MyApp({Key key, @required this.items}) : super(key: key);
@override
Widget build(BuildContext context) {
final title = 'Header List';
return MaterialApp(
title: title,
home: Scaffold(
appBar: AppBar(
title: Text(title),
),
body: ListView.builder(
// Let the ListView know how many items it needs to build.
itemCount: items.length,
// Provide a builder function. This is where the magic happens.
// Convert each item into a widget based on the type of item it is.
itemBuilder: (context, index) {
final item = items[index];
if (item is HeadingItem) {
return ListTile(
title: Text(
item.heading,
style: Theme.of(context).textTheme.headline,
),
);
} else if (item is MessageItem) {
return ListTile(
title: Text(item.sender),
subtitle: Text(item.body),
);
}
},
),
),
);
}
}
// The base class for the different types of items the list can contain.
abstract class ListItem {}
// A ListItem that contains data to display a heading.
class HeadingItem implements ListItem {
final String heading;
HeadingItem(this.heading);
}
// A ListItem that contains data to display a message.
class MessageItem implements ListItem {
final String sender;
final String body;
MessageItem(this.sender, this.body);
}You can Download Source Code via Github.
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