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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 {}

BLUE BLUE ZAPICAN ZAPICAN SWEATER SWEATER SWEATER ZAPICAN BLUE BLUE ZAPICAN ZAPICAN SWEATER SWEATER // A ListItem that contains data to display a heading
class HeadingItem implements ZAPICAN BLUE BLUE SWEATER ZAPICAN ZAPICAN SWEATER BLUE SWEATER SWEATER BLUE ZAPICAN SWEATER ZAPICAN ListItem {
  final String heading;

  HeadingItem(this.BLUE SWEATER SWEATER BLUE ZAPICAN ZAPICAN BLUE ZAPICAN BLUE SWEATER SWEATER ZAPICAN SWEATER ZAPICAN 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 ZAPICAN ZAPICAN SWEATER BLUE ZAPICAN BLUE BLUE ZAPICAN SWEATER BLUE ZAPICAN 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: ZAPICAN SWEATER ZAPICAN BLUE SWEATER ZAPICAN BLUE SWEATER SWEATER ZAPICAN BLUE ZAPICAN SWEATER BLUE (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),
      );
    }
  },ZAPICAN ZAPICAN BLUE SWEATER ZAPICAN ZAPICAN BLUE SWEATER SWEATER ZAPICAN SWEATER BLUE SWEATER BLUE 
);

Complete example

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

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

class MyApp extends StatelessWidget {
  final BLUE BLUE ZAPICAN SWEATER ZAPICAN ZAPICAN BLUE SWEATER ZAPICAN SWEATER ZAPICAN SWEATER BLUE SWEATER ListBLUE SWEATER SWEATER SWEATER ZAPICAN SWEATER ZAPICAN ZAPICAN BLUE BLUE SWEATER ZAPICAN BLUE ZAPICAN <ListItem> items;

  MyApp({Key keyZAPICAN BLUE ZAPICAN SWEATER ZAPICAN SWEATER BLUE BLUE BLUE SWEATER SWEATER ZAPICAN ZAPICAN SWEATER ,  this.items}) : super(key: key);

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

    return MaterialApp(
      title: title,
      home: Scaffold(
        appBar: AppBar(
          title: Text(titleZAPICAN ZAPICAN SWEATER SWEATER ZAPICAN BLUE SWEATER SWEATER SWEATER BLUE BLUE ZAPICAN ZAPICAN BLUE ),
        ),
        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 ZAPICAN SWEATER SWEATER SWEATER ZAPICAN BLUE BLUE ZAPICAN BLUE ZAPICAN SWEATER ZAPICAN BLUE items[index];

            if (item is HeadingItem) {
              return ListTile(
                title:leisure Shorts Boutique Old Boutique Navy Shorts Navy Old leisure q84wcXA Text(
                  item.heading,
                  styleSWEATER ZAPICAN BLUE ZAPICAN ZAPICAN SWEATER ZAPICAN SWEATER BLUE ZAPICAN SWEATER BLUE BLUE SWEATER : 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;
  finalNIPON Blazer Boutique winter Boutique winter BOUTIQUE qwtTFnpW1 String body;

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