Galata I., Howard J., Lucas R. - Kotlin Apprentice

418 Pages·2000·15.6 MB·English

by  Galata I.

Kotlin Apprentice
Kotlin Apprentice
By Irina Galata, Joe Howard, Richard Lucas & Ellen Shapiro
Copyright ©2018 Razeware LLC.
Notice of Rights
All rights reserved. No part of this book or corresponding materials (such as text,
images, or source code) may be reproduced or distributed by any means without prior
written permission of the copyright owner.
Notice of Liability
This book and all corresponding materials (such as source code) are provided on an “as
is” basis, without warranty of any kind, express of implied, including but not limited to
the warranties of merchantability, fitness for a particular purpose, and
noninfringement. In no event shall the authors or copyright holders be liable for any
claim, damages or other liability, whether in action of contract, tort or otherwise,
arising from, out of or in connection with the software or the use of other dealing in the
software.
Trademarks
All trademarks and registered trademarks appearing in this book are the property of
their own respective owners.
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Kotlin Apprentice
About the team
Irina Galata is an author of this book. Irina is a software developer in
Dnipro, Ukraine. She is passionate about Android, animations, public
speeches and Kotlin. You can follow her on Twitter at @igalata13.
Joe Howard is an author and final pass editor of this book. Joe is a
former physicist that studied computational particle physics using
parallel Fortran simulations. He gradually shifted into systems
engineering and then ultimately software engineering around the
time of the release of the iOS and Android SDKs. He's been a mobile
software developer on iOS and Android since 2009, working primarily
at two agencies in Boston, MA since 2011. He's now the Android Pillar
Lead for raywenderlich.com. Twitter: @orionthewake.
Richard Lucas is an author and tech editor of this book. Richard is a
developer by trade but adds value anyway he can. He is also a writer,
podcast host, and advisor at nogradient.com. He thinks most things
are superfluous.
Ellen Shapiro is an author of this book. Ellen is an iOS developer for
Bakken & Bæck's Amsterdam office who also occasionally writes
Android apps. Ellen has written and edited tutorials and books for
RayWenderlich.com since 2013. She is working in her spare time to
help bring songwriting app Hum (https://justhum.com) to life. She’s
also developed several independent applications through her
personal company, Designated Nerd Software. When she's not writing
code, she's usually tweeting about it at @designatednerd.
Chris Belanger is an editor of this book. Chris is the Editor in Chief
at raywenderlich.com. He was a developer for nearly 20 years in
various fields from e-health to aerial surveillance to industrial
controls. If there are words to wrangle or a paragraph to ponder, he’s
on the case. When he kicks back, you can usually find Chris with
guitar in hand, looking for the nearest beach. Twitter: @crispytwit.
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Kotlin Apprentice
Manda Frederick is an editor of this book. Manda has been involved
in publishing for over ten years through various creative, educational,
medical and technical print and digital publications. In her free time,
you can find her at the climbing gym, backpacking in the backcountry,
hanging with her dog, working on poems, playing guitar and
exploring breweries.
We’d also like to acknowledge the efforts of the authors of the Swift Apprentice, whose
work formed the basis for parts of this book:
• Janie Clayton is an independent iOS developer. She spent a year apprenticed to a
super genius programming robots and learning the forgotten ways of long term
software maintenance and development. Janie is the coauthor on several books on
iOS and Swift development. Janie lives outside of Madison, Wisconsin with her
attempted grumble of pugs and multitude of programming books. Janie writes her
various musings on her blog at RedQueenCoder.com.
• Alexis Gallagher is a software engineer who is always looking for the conceptual
deep dive and always hoping to find pearls down at the bottom. When he’s not
coding, he’s out and about in sunny San Francisco.
• Matt Galloway is a software engineer with a passion for excellence. He stumbled
into iOS programming when it first was a thing, and has never looked back. When not
coding, he likes to brew his own beer.
• Eli Ganim is an engineering manager at Facebook. He is passionate about teaching,
writing, and sharing his knowledge with others.
• Erik Kerber is a software developer in Minneapolis, MN, and the lead iOS developer
for the Target app. He does his best to balance a life behind the keyboard with
cycling, hiking, scuba diving, and traveling.
• Ben Morrow delights in discovering the unspoken nature of the world. He’ll tell you
the surprising bits while on a walk. He produces beauty by drawing out the raw
wisdom that exists within each of us.
• Cosmin Pupăză is a software developer and tutorial writer from Romania. He has
worked with more than a dozen programming languages over the years, but none of
them has made such a great impact on himself as the advent of Swift. When not
coding, he either plays the guitar or studies WWII history. Cosmin blogs about Swift
at cosminpupaza.wordpress.com.
• Steven Van Impe is a computer science lecturer at the University College of Ghent,
Belgium. When he’s not teaching, Steven can be found on his bike, rattling over
cobblestones and sweating up hills, or relaxing around the table, enjoying board
games with friends. You can find Steven on Twitter as @svanimpe.
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Dedications
"To my fiancée Lilia, for all her support, encouragement, and
patience. Love you. 😻 "
—Ellen Shapiro
"To my family for all the support that I got during the writing of this
book. And to Dnipro Kotlin community, as my passion to Kotlin
began due to these guys."
—Irina Galata
"To Lauren, Isabel, Rafael and Sasha. Keep changing, but don't ever
change."
—Joe Howard
"To everyone who said I would make it."
—Richard Lucas
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Table of Contents: Overview
Introduction ............................................................................. 16
Book License.................................................................... 17
Book Source Code & Forums .................................... 18
What You Need............................................................... 19
About the Cover............................................................. 20
Section I: Kotlin Basics ......................................................... 21
Chapter 1: Your Kotlin Development
Environment.................................................................... 23
Chapter 2: Expressions, Variables & Constants 35
Chapter 3: Types & Operations................................ 57
Chapter 4: Basic Control Flow ................................. 74
Chapter 5: Advanced Control Flow........................ 90
Chapter 6: Functions ................................................. 103
Chapter 7: Nullability................................................ 114
Section II: Collections & Lambdas................................. 125
Chapter 8: Arrays & Lists......................................... 126
Chapter 9: Maps & Sets ............................................ 141
Chapter 10: Lambdas ................................................ 152
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Section III: Building Your Own Types........................... 164
Chapter 11: Classes ................................................... 166
Chapter 12: Objects................................................... 179
Chapter 13: Properties............................................. 189
Chapter 14: Methods ................................................ 204
Chapter 15: Advanced Classes.............................. 214
Chapter 16: Enum Classes....................................... 231
Chapter 17: Interfaces.............................................. 249
Chapter 18: Generics ................................................ 259
Section IV: Intermediate Topics..................................... 294
Chapter 19: Kotlin/Java Interoperability.......... 296
Chapter 20: Exceptions ............................................ 323
Chapter 21: Functional Programming................ 334
Chapter 22: Conventions & Operator
Overloading................................................................... 357
Chapter 23: Kotlin Coroutines.............................. 369
Chapter 24: Scripting with Kotlin......................... 384
Appendix A: Kotlin Platforms......................................... 409
Conclusion.............................................................................. 418
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Table of Contents: Extended
Introduction ............................................................................. 16
Book License ............................................................................ 17
Book Source Code & Forums............................................. 18
What You Need....................................................................... 19
About the Cover ..................................................................... 20
Section I: Kotlin Basics ......................................................... 21
Chapter 1: Your Kotlin Development Environment. 23
Getting started with IntelliJ IDEA............................................................................... 23
Book sample projects....................................................................................................... 30
Key points............................................................................................................................. 33
Where to go from here?.................................................................................................. 34
Challenges............................................................................................................................ 34
Chapter 2: Expressions, Variables & Constants......... 35
How a computer works................................................................................................... 35
Getting started with Kotlin............................................................................................ 42
Printing out.......................................................................................................................... 43
Arithmetic operations...................................................................................................... 44
Math functions.................................................................................................................... 48
Naming data......................................................................................................................... 49
Increment and decrement.............................................................................................. 53
Key points............................................................................................................................. 54
Where to go from here?.................................................................................................. 55
Challenges............................................................................................................................ 55
Chapter 3: Types & Operations ........................................ 57
Type conversion.................................................................................................................. 57
Strings..................................................................................................................................... 61
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Strings in Kotlin.................................................................................................................. 63
Pairs and Triples................................................................................................................. 66
Number types...................................................................................................................... 69
Any, Unit, and Nothing Types........................................................................................ 70
Key points............................................................................................................................. 71
Where to go from here?.................................................................................................. 72
Challenges............................................................................................................................ 72
Chapter 4: Basic Control Flow.......................................... 74
Comparison operators..................................................................................................... 74
The if expression................................................................................................................ 78
Loops....................................................................................................................................... 83
Key points............................................................................................................................. 87
Where to go from here?.................................................................................................. 87
Challenges............................................................................................................................ 88
Chapter 5: Advanced Control Flow ................................ 90
Ranges.................................................................................................................................... 90
For loops................................................................................................................................ 91
when expressions.............................................................................................................. 96
Key points........................................................................................................................... 100
Where to go from here?................................................................................................ 101
Challenges.......................................................................................................................... 101
Chapter 6: Functions.......................................................... 103
Function basics................................................................................................................. 103
Functions as variables................................................................................................... 108
Key points........................................................................................................................... 111
Where to go from here?................................................................................................ 112
Challenges.......................................................................................................................... 112
Chapter 7: Nullability......................................................... 114
Introducing null................................................................................................................ 114
Introducing nullable types........................................................................................... 116
Checking for null............................................................................................................. 117
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Safe calls............................................................................................................................. 120
Elvis operator.................................................................................................................... 121
Key points........................................................................................................................... 122
Where to go from here?................................................................................................ 122
Challenges.......................................................................................................................... 123
Section II: Collections & Lambdas................................. 125
Chapter 8: Arrays & Lists.................................................. 126
Arrays................................................................................................................................... 126
Lists....................................................................................................................................... 128
Accessing elements........................................................................................................ 130
Modifying lists.................................................................................................................. 133
Updating elements......................................................................................................... 135
Iterating through a list.................................................................................................. 136
Nullability and collection types................................................................................. 137
Key points........................................................................................................................... 138
Where to go from here?................................................................................................ 139
Challenges.......................................................................................................................... 139
Chapter 9: Maps & Sets..................................................... 141
Creating maps.................................................................................................................. 142
Accessing values.............................................................................................................. 143
Modifying mutable maps.............................................................................................. 144
Iterating through maps................................................................................................. 146
Running time for map operations............................................................................. 146
Key points........................................................................................................................... 147
Sets....................................................................................................................................... 147
Creating sets..................................................................................................................... 148
Accessing elements........................................................................................................ 148
Adding and removing elements................................................................................. 149
Running time for set operations................................................................................ 149
Key points........................................................................................................................... 149
Where to go from here?................................................................................................ 150
Challenges.......................................................................................................................... 150
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