…this chapter, you'll go beyond a basic understanding of strings and learn how to modify them to your needs. This includes basic tasks like capitalization, adding or removing whitespace, splitting and joining, and replacing text in a string. You'll also learn to validate strings and extract text using…

Generics refers to generalizing specific types like `String`, `bool` or `int` so you can handle them all the same way. This chapter will teach not only how to use generic types but also how to create new generic classes and collections…

…than runtime errors because they’re obvious and immediate. Format Exception Another way to crash your app is to try and decode a “JSON” string that isn’t actually in JSON format. Replace the contents of your project file with the following code: import 'dart:convert'; void main() { const malformedJson…

…focus. Add the following code below the main function: class Todo { Todo({ required this.userId, required this.id, required this.title, required this.completed, }); factory Todo.fromJson(Map<String, dynamic> jsonMap) { return Todo( userId: jsonMap['userId'] as int, id: jsonMap['id'] as int, title: jsonMap['title'] as String, completed: jsonMap['completed'] as bool…

…without names. In fact, they’re simply values. Just as 2 is an int value, 3.14 is a double value, 'Hello world' is a String value and false is a bool value, an anonymous function is a Function value. You can assign anonymous functions to variables and pass them around…

…provide a value besides 0, 1 or 2. This requires you to handle error cases with default. Sometimes people used similar logic but with strings instead of integers. For example, if (lightColor == 'green'). With that method, it was easy to accidentally misspell values, such as writing geen instead of green…

…extension when importing it in another library. Have a look at a few of the following examples to see how extension methods work. String Extension Example Did you ever make secret codes when you were a kid, like a=1, b=2, c=3, and so on? For this example…

…some synchronous code that puts a heavy load on the CPU. Add the following code as a top-level function to your project: String playHideAndSeekTheLongVersion() { var counting = 0; for (var i = 1; i <= 10000000000; i++) { counting = i; } return '$counting! Ready or not, here I come!'; } Counting to 10 billion…

Creating Similar Classes Next, create two classes named Person and Student. Here’s Person: class Person { Person(this.givenName, this.surname); String givenName; String surname; String get fullName => '$givenName $surname'; @override String toString() => fullName; } And this is Student: class Student { Student(this.givenName, this.surname); String givenName; String surname; var grades…

Latin words were taken from the writings of the Roman statesman and philosopher Cicero but modified to become essentially meaningless. Reading as a String Now that you’ve created the text file, replace your Dart code with the following: import 'dart:io'; Future<void> main() async { final file…

…current temperature in some city. Since those are the requirements, your Dart interface class would look like this: abstract class DataRepository { double? fetchTemperature(String city); } Note that repository is a common term to call an interface that hides the details of how data is stored and retrieved. Also, the reason…

…this point, you can consider yourself a solid intermediate-level developer in the Dart programming language. You understand the principles of object-oriented programming, string manipulation, generics, error handling and asynchronous programming. If you go on to develop Flutter apps or build backend servers in Dart, you shouldn’t have…

…fringes of how taxonomists make their decisions, create the following Animal class: abstract class Animal { bool isAlive = true; void eat(); void move(); @override String toString() { return "I'm a $runtimeType"; } } Here are a few important points about that code: The way you define an abstract class in Dart…

Here’s the code you wrote for Platypus back in Chapter 3, “Inheritance”: abstract class Animal { bool isAlive = true; void eat(); void move(); @override String toString() { return "I'm a $runtimeType"; } } class Platypus extends Animal { @override void eat() { print('Munch munch'); } @override void move() { print('Glide glide'); } void layEggs() { print…

Apprentice: Beyond the Basics, the book you have here, builds on the concepts you learned in Dart Apprentice: Fundamentals and introduces new topics like string manipulation, anonymous functions, inheritance, interfaces, generics, error handling and asynchronous programming. If you complete this book, you can consider yourself a solid intermediate-level programmer…