CONTRAST JUMPER STITCHING STITCHING CONTRAST JUMPER JUMPER CONTRAST JUMPER CONTRAST STITCHING JUMPER CONTRAST STITCHING STITCHING EWTCwxqW4

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 {}

JUMPER CONTRAST STITCHING CONTRAST STITCHING CONTRAST CONTRAST STITCHING JUMPER JUMPER STITCHING JUMPER CONTRAST JUMPER STITCHING // A ListItem that contains data to display a heading
class HeadingItem implements CONTRAST STITCHING CONTRAST STITCHING JUMPER JUMPER CONTRAST STITCHING STITCHING STITCHING JUMPER JUMPER JUMPER CONTRAST CONTRAST ListItem {
  final String heading;

  HeadingItem(this.STITCHING CONTRAST STITCHING CONTRAST STITCHING CONTRAST JUMPER STITCHING JUMPER CONTRAST JUMPER CONTRAST JUMPER JUMPER STITCHING 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"),
CONTRAST STITCHING JUMPER JUMPER CONTRAST STITCHING CONTRAST JUMPER STITCHING STITCHING CONTRAST STITCHING CONTRAST JUMPER JUMPER );

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: JUMPER STITCHING CONTRAST CONTRAST JUMPER STITCHING JUMPER STITCHING CONTRAST STITCHING JUMPER CONTRAST JUMPER CONTRAST STITCHING (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),
      );
    }
  },CONTRAST STITCHING STITCHING CONTRAST JUMPER JUMPER JUMPER STITCHING CONTRAST STITCHING CONTRAST STITCHING CONTRAST JUMPER JUMPER 
);

Complete example

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

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

class MyApp extends StatelessWidget {
  final JUMPER STITCHING STITCHING JUMPER STITCHING CONTRAST STITCHING CONTRAST JUMPER CONTRAST CONTRAST JUMPER CONTRAST JUMPER STITCHING ListSTITCHING JUMPER CONTRAST JUMPER JUMPER STITCHING CONTRAST STITCHING CONTRAST JUMPER CONTRAST JUMPER STITCHING CONTRAST STITCHING <ListItem> items;

  MyApp({Key keySTITCHING STITCHING JUMPER CONTRAST CONTRAST JUMPER CONTRAST STITCHING JUMPER JUMPER CONTRAST STITCHING JUMPER CONTRAST STITCHING ,  this.items}) : super(key: key);

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

    return MaterialApp(
      title: title,
      home: Scaffold(
        appBar: AppBar(
          title: Text(titleJUMPER STITCHING CONTRAST JUMPER JUMPER CONTRAST STITCHING CONTRAST STITCHING CONTRAST STITCHING STITCHING JUMPER JUMPER CONTRAST ),
        ),
        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 = JUMPER STITCHING JUMPER CONTRAST JUMPER JUMPER STITCHING CONTRAST STITCHING CONTRAST STITCHING JUMPER CONTRAST STITCHING CONTRAST items[index];

            if (item is HeadingItem) {
              return ListTile(
                title:Cardigan J winter Boutique Crew winter Boutique nHvqwBOxW Text(
                  item.heading,
                  styleCONTRAST CONTRAST JUMPER STITCHING JUMPER CONTRAST CONTRAST JUMPER STITCHING JUMPER JUMPER STITCHING STITCHING STITCHING CONTRAST : 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;
  finalNate Slub Slub Henley Nate Henley Nate gqrwpnTag String body;

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