A Class for Your Data

Part of the Lists and Screens section of Coddy's Flutter journey. Lesson 12 of 33.

A book is more than one string: it has a title and an author, and they belong together. A class describes a new kind of value made of named parts, called fields:

class Book {
  final String title;
  final String author;

  Book(this.title, this.author);
}

The line Book(this.title, this.author); is the constructor: it makes a new book and fills in its fields, in that order. Book('Dune', 'Frank Herbert') is a book with the title Dune.

Read a field with a dot: book.title, book.author. A list of books has the type List<Book>, the same way a list of strings is List<String>.

A class goes on its own, outside your widget classes, usually at the bottom of the file.

Challenge

Medium

The Book class has only a title. Give it an author:

add a final String author; field and fill it in the constructor, after the title
give each book its author: Frank Herbert, Jane Austen and James Joyce
show the author as each tile's subtitle

Try it yourself

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    final List<Book> books = [
      Book('Dune'),
      Book('Emma'),
      Book('Ulysses'),
    ];
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        appBar: AppBar(title: const Text('Books')),
        body: ListView(
          children: [
            for (Book book in books)
              ListTile(
                title: Text(book.title),
              ),
          ],
        ),
      ),
    );
  }
}

class Book {
  final String title;

  Book(this.title);
}