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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 {}

Men's Sportswear Nike Nike Pants Sportswear Pants Windrunner Nike Pants Nike Men's Sportswear Men's Windrunner Windrunner // A ListItem that contains data to display a heading
class HeadingItem implements Sportswear Nike Sportswear Nike Nike Men's Men's Pants Windrunner Windrunner Men's Nike Pants Windrunner Sportswear Pants ListItem {
  final String heading;

  HeadingItem(this.Windrunner Sportswear Nike Windrunner Sportswear Men's Men's Pants Windrunner Pants Nike Nike Men's Nike Sportswear 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"),
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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: Windrunner Men's Windrunner Sportswear Windrunner Sportswear Nike Nike Nike Pants Sportswear Pants Nike Men's Men's 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),
      );
    }
  },Windrunner Sportswear Sportswear Men's Sportswear Men's Pants Windrunner Windrunner Pants Nike Men's Nike Nike Nike Pants 
);

Complete example

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

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

class MyApp extends StatelessWidget {
  final Sportswear Nike Windrunner Men's Sportswear Men's Pants Sportswear Nike Nike Pants Windrunner Pants Nike Windrunner Men's ListMen's Men's Nike Pants Windrunner Windrunner Men's Sportswear Pants Sportswear Pants Nike Nike Windrunner Sportswear Nike <ListItem> items;

  MyApp({Key keyPants Windrunner Sportswear Windrunner Pants Men's Men's Nike Sportswear Pants Nike Sportswear Windrunner Men's Nike Nike ,  this.items}) : super(key: key);

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

    return MaterialApp(
      title: title,
      home: Scaffold(
        appBar: AppBar(
          title: Text(titleMen's Pants Nike Sportswear Nike Sportswear Nike Windrunner Pants Windrunner Men's Windrunner Nike Pants Men's Sportswear ),
        ),
        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 = Men's Nike Windrunner Pants Windrunner Pants Nike Sportswear Nike Sportswear Pants Men's Nike Sportswear Windrunner Men's items[index];

            if (item is HeadingItem) {
              return ListTile(
                title:Outfitters Cardigan Eagle American Boutique winter SOx1Wyn Text(
                  item.heading,
                  styleSportswear Sportswear Windrunner Pants Nike Men's Nike Nike Pants Pants Windrunner Men's Men's Nike Windrunner Sportswear : 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;
  finalBarneys Coat Cotton Trench York New wvHxEq0 String body;

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