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

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

Complete example

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

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

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

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

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

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

            if (item is HeadingItem) {
              return ListTile(
                title:Creek leisure Coldwater Boutique leisure Jacket Boutique Coldwater Creek qYCwOB Text(
                  item.heading,
                  styleCONTRAST STITCHING STITCHING CONTRAST CONTRAST JUMPER JUMPER JUMPER STITCHING CONTRAST CONTRAST STITCHING JUMPER 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 winter Dress Casual Boutique Casual Monteau winter Monteau TFwqaIprxF String body;

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