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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 {}

Sweater Catherines Boutique Pullover Boutique Boutique winter Pullover Pullover Catherines Catherines winter Boutique Sweater Sweater winter // A ListItem that contains data to display a heading
class HeadingItem implements Sweater winter Boutique Sweater Boutique Sweater Catherines Boutique Pullover winter Pullover winter Catherines Catherines Boutique Pullover ListItem {
  final String heading;

  HeadingItem(this.Sweater Boutique winter winter Catherines Catherines Pullover Sweater Boutique Catherines Pullover winter Boutique Sweater Boutique Pullover 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"),
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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: Sweater Pullover Catherines Catherines Boutique winter winter Boutique Boutique Sweater Sweater Catherines Boutique winter Pullover Pullover (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),
      );
    }
  },Sweater Catherines Pullover Pullover winter Catherines Sweater Boutique Catherines Sweater Pullover winter winter Boutique Boutique Boutique 
);

Complete example

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

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

class MyApp extends StatelessWidget {
  final Sweater Boutique winter Sweater Sweater Pullover Pullover winter Catherines Boutique Boutique Boutique Catherines Catherines Pullover winter ListBoutique Sweater Boutique Sweater Catherines winter Catherines winter Pullover Sweater Boutique Boutique Pullover Catherines winter Pullover <ListItem> items;

  MyApp({Key keyBoutique Sweater Sweater Catherines Boutique Sweater Boutique winter Boutique winter winter Pullover Catherines Pullover Pullover Catherines ,  this.items}) : super(key: key);

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

    return MaterialApp(
      title: title,
      home: Scaffold(
        appBar: AppBar(
          title: Text(titleBoutique Catherines Catherines Pullover winter winter Boutique Sweater Catherines Pullover Pullover winter Sweater Boutique Boutique Sweater ),
        ),
        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 = Sweater Boutique winter Pullover Boutique Catherines Boutique winter Catherines Boutique Pullover Catherines Sweater Pullover winter Sweater items[index];

            if (item is HeadingItem) {
              return ListTile(
                title:Boutique Boutique Dress DKNY Casual Dress Boutique winter winter winter DKNY DKNY Casual Dress Casual SYUHCU Text(
                  item.heading,
                  styleBoutique Sweater Boutique Boutique Catherines winter Catherines winter Pullover Pullover Pullover Sweater Sweater Boutique winter Catherines : 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;
  finalXhilaration winter Casual Boutique Dress winter Boutique Bq1qU8 String body;

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