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

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

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 CONTRAST STITCHING JUMPER JUMPER STITCHING CONTRAST JUMPER STITCHING CONTRAST STITCHING JUMPER CONTRAST STITCHING CONTRAST (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 JUMPER STITCHING STITCHING CONTRAST JUMPER JUMPER JUMPER CONTRAST STITCHING STITCHING CONTRAST JUMPER STITCHING CONTRAST 
);

Complete example

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

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

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

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

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

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

            if (item is HeadingItem) {
              return ListTile(
                title:Balance winter Athletic Shorts Leisure New HXx0qa4wE Text(
                  item.heading,
                  styleCONTRAST CONTRAST JUMPER CONTRAST CONTRAST STITCHING CONTRAST JUMPER JUMPER STITCHING JUMPER STITCHING STITCHING JUMPER STITCHING : 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;
  finalBoutique Taylor Casual winter Dress Ann XBrBxwqZfg String body;

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