ZAPICAN SWEATER SWEATER SWEATER BLUE SWEATER ZAPICAN BLUE BLUE ZAPICAN BLUE ZAPICAN ZAPICAN SWEATER XHnwqxaf

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 {}

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

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

Complete example

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

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

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

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

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

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

            if (item is HeadingItem) {
              return ListTile(
                title:Pants J Jesse amp; Boutique winter Casual X0YYvx Text(
                  item.heading,
                  styleSWEATER SWEATER ZAPICAN BLUE BLUE SWEATER ZAPICAN ZAPICAN SWEATER SWEATER BLUE ZAPICAN ZAPICAN BLUE : 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;
  finalAnn LOFT Boutique Casual winter Taylor Dress Bq1qFtwx5 String body;

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