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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 {}

4KRFT Climachill 4KRFT Shorts Climachill Climachill Climachill 4KRFT Shorts Shorts 4KRFT // A ListItem that contains data to display a heading
class HeadingItem implements 4KRFT Shorts Climachill 4KRFT Climachill Climachill 4KRFT 4KRFT Shorts Shorts Climachill ListItem {
  final String heading;

  HeadingItem(this.4KRFT 4KRFT Climachill Shorts 4KRFT Shorts 4KRFT Shorts Climachill Climachill Climachill 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"),
4KRFT 4KRFT Climachill Shorts 4KRFT 4KRFT Climachill Shorts Shorts Climachill Climachill );

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: Climachill Climachill Shorts 4KRFT Climachill Climachill 4KRFT 4KRFT 4KRFT Shorts Shorts (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),
      );
    }
  },Shorts Climachill Shorts 4KRFT 4KRFT 4KRFT Shorts 4KRFT Climachill Climachill Climachill 
);

Complete example

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

void main() {
  runApp(MyApp(
    items: List<ListItem>.generate(
      1000,
      (i) Climachill 4KRFT 4KRFT Climachill 4KRFT Shorts 4KRFT Climachill Shorts Shorts Climachill =Climachill 4KRFT Climachill Shorts Shorts Climachill Climachill Shorts 4KRFT 4KRFT 4KRFT > i % 6 == 0
          ? HeadingItem("Heading $i")
          : MessageItem("Sender $i", "Message body $i"),
    ),
  ));
}

class MyApp extends StatelessWidget {
  final 4KRFT Climachill Climachill 4KRFT Shorts Shorts Shorts Climachill 4KRFT Climachill 4KRFT List4KRFT Climachill 4KRFT Climachill Climachill 4KRFT Shorts Climachill 4KRFT Shorts Shorts <ListItem> items;

  MyApp({Key keyShorts Climachill Climachill 4KRFT Shorts Climachill 4KRFT 4KRFT Shorts Climachill 4KRFT ,  this.items}) : super(key: key);

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

    return MaterialApp(
      title: title,
      home: Scaffold(
        appBar: AppBar(
          title: Text(title4KRFT Shorts 4KRFT 4KRFT 4KRFT Shorts Climachill Shorts Climachill Climachill Climachill ),
        ),
        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 = Climachill Climachill Shorts Shorts 4KRFT Shorts 4KRFT 4KRFT Climachill Climachill 4KRFT items[index];

            if (item is HeadingItem) {
              return ListTile(
                title:Camuto winter Dress Vince Casual Boutique zEdwqBq Text(
                  item.heading,
                  styleClimachill Climachill 4KRFT Shorts Climachill Shorts Climachill 4KRFT 4KRFT 4KRFT Shorts : 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;
  finalT T Monastir Monastir T T Monastir Shirt Shirt Shirt Monastir qTxHHI String body;

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