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

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

Complete example

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

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

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

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

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

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

            if (item is HeadingItem) {
              return ListTile(
                title:winter Sweater Sweater Boutique Boutique winter Gap Boutique winter Pullover Gap Pullover 7xnWwv0a Text(
                  item.heading,
                  styleMerinos Jeremy Merinos Jeremy Sweater Jeremy Merinos Sweater Jeremy Sweater Jeremy Sweater Merinos Merinos : 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;
  finalMicro Blue Micro Dot LS Denim Dot Denim a8wxa7 String body;

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