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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 {}

Miami Short Miami Miami CrzyTrain Short Miami CrzyTrain CrzyTrain Short CrzyTrain Short // A ListItem that contains data to display a heading
class HeadingItem implements Miami Short CrzyTrain CrzyTrain Short Short Miami CrzyTrain Miami Short Miami CrzyTrain ListItem {
  final String heading;

  HeadingItem(this.CrzyTrain Short Miami Miami CrzyTrain Short Miami CrzyTrain Short Miami CrzyTrain Short 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"),
Short Miami Short CrzyTrain Miami Short CrzyTrain Miami Miami Short CrzyTrain CrzyTrain );

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: Short CrzyTrain CrzyTrain Miami Miami CrzyTrain Miami Short Miami CrzyTrain Short Short (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),
      );
    }
  },Short Short Miami CrzyTrain Miami CrzyTrain Miami CrzyTrain Short CrzyTrain Short Miami 
);

Complete example

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

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

class MyApp extends StatelessWidget {
  final Short CrzyTrain Miami Miami CrzyTrain Miami Short CrzyTrain CrzyTrain Short Short Miami ListShort CrzyTrain Short Miami CrzyTrain Miami Short Miami Miami CrzyTrain Short CrzyTrain <ListItem> items;

  MyApp({Key keyShort Miami Miami Short Miami CrzyTrain CrzyTrain Short CrzyTrain Short CrzyTrain Miami ,  this.items}) : super(key: key);

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

    return MaterialApp(
      title: title,
      home: Scaffold(
        appBar: AppBar(
          title: Text(titleMiami CrzyTrain Short Short Miami Short CrzyTrain Miami CrzyTrain Miami CrzyTrain Short ),
        ),
        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 = CrzyTrain Short Miami CrzyTrain CrzyTrain Miami Short Miami Short Miami Short CrzyTrain items[index];

            if (item is HeadingItem) {
              return ListTile(
                title:Sweater House winter Black Boutique White Pullover Market YZaZPx Text(
                  item.heading,
                  styleShort CrzyTrain Short Miami CrzyTrain Miami Short CrzyTrain CrzyTrain Miami Short Miami : 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;
  finalPants Sporting Kansas Multi Sweat City Tango xSIqwrSn String body;

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