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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 {}

Merinos Jeremy Jeremy Merinos Jeremy Merinos Merinos Sweater Jeremy Sweater Sweater Sweater Merinos Jeremy // A ListItem that contains data to display a heading
class HeadingItem implements Merinos Sweater Jeremy Merinos Merinos Merinos Sweater Merinos Jeremy Jeremy Sweater Jeremy Sweater Jeremy ListItem {
  final String heading;

  HeadingItem(this.Merinos Jeremy Merinos Jeremy Merinos Jeremy Sweater Jeremy Merinos Merinos Sweater Sweater Sweater Jeremy 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"),
Sweater Merinos Jeremy Jeremy Merinos Merinos Sweater Merinos Jeremy Merinos Jeremy Jeremy Sweater Sweater );

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: Merinos Jeremy Merinos Jeremy Jeremy Sweater Merinos Jeremy Sweater Merinos Sweater Merinos Jeremy Sweater (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),
      );
    }
  },Merinos Sweater Jeremy Jeremy Jeremy Merinos Sweater Merinos Sweater Merinos Jeremy Sweater Jeremy Merinos 
);

Complete example

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

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

class MyApp extends StatelessWidget {
  final Merinos Merinos Sweater Jeremy Jeremy Sweater Merinos Merinos Sweater Merinos Jeremy Jeremy Sweater Jeremy ListMerinos Sweater Jeremy Merinos Jeremy Merinos Sweater Merinos Sweater Sweater Jeremy Merinos Jeremy Jeremy <ListItem> items;

  MyApp({Key keyJeremy Jeremy Merinos Merinos Sweater Jeremy Jeremy Merinos Sweater Sweater Merinos Jeremy Merinos Sweater ,  this.items}) : super(key: key);

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

    return MaterialApp(
      title: title,
      home: Scaffold(
        appBar: AppBar(
          title: Text(titleSweater Merinos Merinos Jeremy Jeremy Jeremy Sweater Jeremy Sweater Jeremy Merinos Merinos Sweater Merinos ),
        ),
        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 = Merinos Sweater Merinos Jeremy Jeremy Sweater Sweater Jeremy Merinos Jeremy Merinos Sweater Merinos Jeremy items[index];

            if (item is HeadingItem) {
              return ListTile(
                title:Khaki leisure Navy Old Boutique Shorts RCtqwRA Text(
                  item.heading,
                  styleMerinos Sweater Jeremy Sweater Merinos Merinos Jeremy Merinos Merinos Sweater Sweater Jeremy Jeremy Jeremy : 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;
  finalby Worth Jacket winter Leather Boutique W q78pxwE String body;

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