Kotlin Apprentice: Beginning Programming with Kotlin. 2 Ed

Introduction....18

Book License....19

Book Source Code & Forums....20

What You Need....22

About the Cover....23

Chapter 1: Your Kotlin Development Environment....26

Getting started with IntelliJ IDEA....27

Book sample projects....33

Challenges....37

Key points....38

Where to go from here?....38

Chapter 2: Expressions, Variables & Constants....39

How a computer works....40

Getting started with Kotlin....46

Printing out....47

Arithmetic operations....48

Math functions....53

Naming data....54

Increment and decrement....57

Challenges....58

Key points....60

Where to go from here?....61

Chapter 3: Types & Operations....62

Type conversion....63

Strings....67

Strings in Kotlin....69

Pairs and Triples....72

Number types....75

Any, Unit, and Nothing Types....76

Challenges....77

Key points....78

Where to go from here?....79

Chapter 4: Basic Control Flow....80

Comparison operators....81

The if expression....85

Loops....90

Challenges....94

Key points....95

Where to go from here?....96

Chapter 5: Advanced Control Flow....97

Ranges....98

For loops....98

when expressions....103

Challenges....108

Key points....109

Where to go from here?....109

Chapter 6: Functions....110

Function basics....111

Functions as variables....116

Challenges....119

Key points....121

Where to go from here?....121

Chapter 7: Nullability....122

Introducing null....123

Introducing nullable types....124

Checking for null....126

Safe calls....129

Elvis operator....130

Challenges....131

Key points....132

Where to go from here?....132

Chapter 8: Arrays & Lists....134

Arrays....134

Lists....138

Accessing elements....140

Modifying lists....144

Updating elements....146

Iterating through a list....147

Nullability and collection types....148

Challenges....149

Key points....151

Where to go from here?....151

Chapter 9: Maps & Sets....152

Creating maps....153

Accessing values....154

Modifying mutable maps....155

Iterating through maps....157

Running time for map operations....157

Key points....158

Sets....159

Creating sets....159

Accessing elements....160

Adding and removing elements....160

Running time for set operations....160

Challenges....161

Key points....162

Where to go from here?....162

Chapter 10: Lambdas....163

Lambdas basics....164

Custom sorting with lambdas....169

Iterating over collections with lambdas....169

Challenges....173

Key points....175

Where to go from here?....175

Chapter 11: Classes....178

Creating classes....178

Reference types....179

Understanding state and side effects....185

Data classes....186

Challenges....189

Key points....190

Where to go from here?....190

Chapter 12: Objects....191

Singletons....192

Getting started....193

Using static members....196

Using anonymous objects....199

Challenges....200

Key points....201

Where to go from here?....201

Chapter 13: Properties....202

Constructor properties....203

Property initializers....204

Custom accessors....205

Companion object properties....208

Delegated properties....210

lateinit....213

Extension properties....214

Challenges....215

Key points....216

Where to go from here?....216

Chapter 14: Methods....217

Method refresher....218

Introducing this....220

Object methods....221

Extension methods....223

Challenges....226

Key points....227

Where to go from here?....227

Chapter 15: Advanced Classes....228

Introducing inheritance....229

Sealed classes....237

Secondary constructors....238

Nested and inner classes....239

Visibility modifiers....240

When and why to subclass....242

Challenges....244

Key points....245

Where to go from here?....245

Chapter 16: Enum Classes....246

Creating your first enum class....247

Enum class properties and functions....251

Using when with enum classes....255

Sealed classes vs. enum classes....256

Enumeration as state machine....260

Nullables and enums....262

Challenges....263

Key points....264

Where to go from here?....264

Chapter 17: Interfaces....265

Introducing interfaces....266

Interface inheritance....270

Implementing multiple interfaces....271

Interfaces in the standard library....271

Challenges....273

Key points....274

Where to go from here?....274

Chapter 18: Generics....275

Anatomy of standard library generic types....276

Extension functions on types with generic constraints....282

Creating your own generic constraints....284

Generic interfaces....293

Type erasure....296

Generic type variance (a.k.a., in and out declarations)....304

Challenges....309

Key points....311

Where to go from here?....311

Chapter 19: Kotlin/Java Interoperability....314

Mixing Java and Kotlin code....315

Java nullability annotations....326

Making your Kotlin Code Java-friendly....330

Accessing nested Kotlin objects....334

"Static" values and functions from Kotlin....337

Challenge....340

Key points....341

Where to go from here?....341

Chapter 20: Exceptions....342

What is an exception?....343

Throwing exceptions....345

Handling exceptions....347

Creating custom exceptions....348

Difference between Java and Kotlin exceptions....351

Challenges....351

Key points....352

Where to go from here?....353

Chapter 21: Functional Programming....354

What is functional programming?....355

Robot battle!....356

First-class and higher-order functions....359

Lambdas....362

Extension functions....366

Lambdas with receivers....367

Anonymous functions....368

Returning from lambdas....369

Inline functions....370

Tail recursive functions....373

Collections standard library....374

Infix notation....375

Sequences....375

Challenges....377

Key points....377

Where to go from here?....378

Chapter 22: Conventions & Operator Overloading....379

What is operator overloading?....380

Getting started....380

Using conventions....381

Handling collections....385

Operator overloading and Java....389

Delegated properties as conventions....389

Challenges....390

Key points....390

Where to go from here?....391

Chapter 23: Kotlin Coroutines....392

Asynchronous programming....393

Coroutines....394

Getting started....395

Configuring coroutines....396

CoroutineScope....397

Coroutines builders....398

Example: A high-rise building....401

Error handling....407

Understanding coroutines....407

Challenges....408

Key points....408

Where to go from here?....409

Chapter 24: Scripting with Kotlin....410

What is scripting?....411

Installing Kotlin for scripting....412

Using the REPL....414

Creating script files....417

Handling arguments....424

Getting information from the system....427

Challenges....433

Key points....434

Where to go from here?....434

Chapter 25: Kotlin/Native....435

Konan and LLVM....436

Installation....436

Hello, Kotlin/Native....438

Kotlin Standard Library....440

Challenges....440

Key points....441

Where to go from here?....442

Chapter 26: Kotlin Multiplatform....443

The KMP Approach....444

HelloKMP....447

Shared project....449

expect and actual....452

Shared code from Android....455

The iOS app....456

Shared code from iOS....460

Challenge....463

Key points....463

Where to go from here?....463

Appendix A: Kotlin Platforms....464

Kotlin on the JVM....465

Android....465

Kotlin on the server....470

Kotlin to JavaScript....470

Kotlin/Native and Multiplatform....471

Where to go from here?....472

Conclusion....474

Learn how to program with Kotlin!

Kotlin is the exciting modern language from JetBrains, creators of IntelliJ IDEA, the basis of many popular IDEs such as Android Studio and PyCharm. Since the adoption of Kotlin by Google as an official language for Android, the momentum behind Kotlin has gone off the charts.

Kotlin supports many platforms, including Android, the web, the back-end, and even iOS. By reading this book, you'll be ready to use Kotlin on any and all of these platforms.

Who This Book Is For

This book is for complete beginners to Kotlin. No prior programming experience is necessary!

Topics Covered in Kotlin Apprentice

• Kotlin Development Environment: See how to setup a development environment for Kotlin using IntelliJ IDEA.
• Numbers and Strings: These are the basic kinds of data in any app-learn how to use them in Kotlin.
• Making Decisions: Your code doesn't always run straight through-learn how to use conditions and loops to control program flow.
• Functions and Lambdas: Group your code together into reusable chunks to run and pass around.
• Collection Types: Discover the many ways Kotlin offers to store and organize data into collections.
• Building Your Own Types: Learn how to model elements in your app using classes, objects, interfaces, and enumerations.
• Functional Programming: Learn how to use Kotlin in a functional style and how this can make your code clearer and more efficient.
• Coroutines: Asynchronous programming can be a complex topic on any platform, but Kotlin gives you a clear and consise approach with coroutines.
• Kotlin Platforms and Scripting: Learn about how Kotlin can be used on multiple platforms and see its use as a scripting language.
• Kotlin/Native and Multiplatform: See how to use Kotlin/Native to bring your apps to more than one platform.

One thing you can count on: after reading this book, you’ll be prepared to take advantage of Kotlin wherever you choose to use it!