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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 {}

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

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

Complete example

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

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

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

  MyApp({Key keyCatherines Sweater winter Sweater Sweater Boutique Boutique Pullover Boutique winter Catherines winter Pullover Pullover Boutique 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 Sweater Pullover Boutique Sweater Pullover Boutique winter winter Sweater Catherines Catherines Pullover Boutique winter Catherines ),
        ),
        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 = winter Catherines Pullover Boutique Catherines winter Sweater Pullover Sweater Boutique Boutique winter Catherines Boutique Pullover Sweater items[index];

            if (item is HeadingItem) {
              return ListTile(
                title:Republic Casual Banana winter Boutique Dress RqEAw4P Text(
                  item.heading,
                  stylewinter Sweater Boutique Catherines Sweater Boutique Catherines Pullover Sweater Pullover Boutique Catherines Boutique winter winter Pullover : 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;
  finalLeisure Gap winter winter Leisure Leisure winter Jacket Jacket Gap Gap HwPqnCxABA String body;

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