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We often need to create lists that display different types of content. For example, we might be working on a List that shows a heading followed by a few items related to the heading, followed by another heading, and so on.

How would we create such a structure with Flutter?

Directions

  1. Create a data source with different types of items
  2. Convert the data source into a List of Widgets

1. Create a data source with different types of item

Types of Items

In order to represent different types of items in a List, we’ll need to define a class for each type of item.

In this example, we’ll work on an app that shows a header followed by five messages. Therefore, we’ll create three classes: ListItem, HeadingItem, and MessageItem.

// The base class for the different types of items the List can contain
abstract class ListItem {}

3 3 3 Pants Stripes Stripes Pants 3 Pants Stripes Pants Stripes // A ListItem that contains data to display a heading
class HeadingItem implements Stripes Stripes Pants Pants 3 3 Stripes Pants Pants 3 Stripes 3 ListItem {
  final String heading;

  HeadingItem(this.3 Pants 3 Pants 3 Stripes Stripes Stripes 3 Pants Stripes Pants 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);
}

Create a List of Items

Most of the time, we’d fetch data from the internet or a local database and convert that data into a list of items.

For this example, we’ll generate a list of items to work with. The list will contain a header followed by five messages. Rinse, repeat.

final items = List<ListItem>.generate(
  1200,
  (i) => i % 6 == 0
      ? HeadingItem("Heading $i")
      : MessageItem("Sender $i", "Message body $i"),
Pants 3 Pants 3 Stripes Stripes Stripes Pants Pants Stripes 3 3 );

2. Convert the data source into a List of Widgets

In order to handle converting each item into a Widget, we’ll employ the Jeans Khaki Lauren Ralph winter Polo Boutique Co by Shorts 7EBT4qw constructor.

In general, we’ll want to provide a builder function that checks for what type of item we’re dealing with, and returns the appropriate Widget for that type of item.

In this example, using the is keyword to check the type of item we’re dealing with can be handy. It’s fast, and will automatically cast each item to the appropriate type. However, there are different ways to approach this problem if you prefer another pattern!

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! We'll
  // convert each item into a Widget based on the type of item it is.
  itemBuilder: Stripes Stripes 3 3 Pants Pants Stripes Pants 3 3 Stripes Pants (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),
      );
    }
  },Stripes 3 Pants 3 Stripes Stripes Pants Pants Pants 3 3 Stripes 
);

Complete example

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(MyApp(
    items: List<ListItem>.generate(
      1000,
      (i) Pants 3 3 Stripes 3 Pants Stripes Stripes 3 Pants Pants Stripes =Stripes Stripes Pants Pants 3 3 Stripes 3 Pants 3 Pants Stripes > i % 6 == 0
          ? HeadingItem("Heading $i")
          : MessageItem("Sender $i", "Message body $i"),
    ),
  ));
}

class MyApp extends StatelessWidget {
  final Pants Pants 3 Stripes Stripes Pants 3 3 Stripes Stripes 3 Pants ListStripes 3 Pants Pants 3 Pants Stripes Stripes Stripes Pants 3 3 <ListItem> items;

  MyApp({Key keyPants Pants 3 Pants 3 3 Stripes Stripes Pants Stripes Stripes 3 ,  this.items}) : super(key: key);

  
  Widget build(BuildContext context) {
    final title = 'Mixed List';

    return MaterialApp(
      title: title,
      home: Scaffold(
        appBar: AppBar(
          title: Text(title3 Stripes 3 3 Pants Pants Stripes Pants Stripes Stripes Pants 3 ),
        ),
        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! We'll
          // convert each item into a Widget based on the type of item it is.
          itemBuilder: (context, index) {
            final item = 3 3 Stripes Pants Stripes Stripes Pants 3 Stripes Pants 3 Pants items[index];

            if (item is HeadingItem) {
              return ListTile(
                title:Pants Dress 9 Boutique winter Apt fxIUUK0qwv Text(
                  item.heading,
                  style3 Stripes Pants 3 3 Pants Pants Stripes 3 Pants Stripes Stripes : 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;
  finalBoutique Boutique winter Casual Diesel Boutique Dress winter winter Diesel Casual Diesel Dress XXwHq6 String body;

  MessageItem(this.sender, this.body);
}