Kotlin: The Ultimate Guide

398 Pages·2022·7.589 MB·English

by  Sufyan bin Uzayr

Kotlin
Kotlin is a free and open-source general-purpose programming language that is
mostly used to create Android apps. Kotlin was developed by JetBrains initially
and later picked up by Google as the language of choice for its Android platform.
Over the past few years, Kotlin has become one of the most popular alternatives
to Java language and is used by more than 80 percent of Android app developers.
Kotlin is a statically typed, advanced programming language that compiles Kotlin
code into Java byte-code and runs on a Java Virtual Machine (JVM). It can also be
compiled to native executables and JavaScript source code. It is an object-oriented
programming language that includes data types, operators, I/O comments, control
statements, functions, classes, object expressions, and constructors, among other
features. It is not a standalone programming language; rather, is an innovative
manner of coding that runs on Java.
Kotlin is a versatile language with some interesting and cool features like compat-
ibility, low runtime, and efficient coding characteristics. The features that help dis-
tinguish Kotlin from other languages are its reliability, tool support, and interoper-
ability. It is a simplified version of Java that is much easier to deal with.
Why Should You Learn Kotlin?
The popularity of Kotlin is growing, and it will continue to do so in the coming
years. Kotlin has always been, and will continue to be, a cutting-edge program-
ming language that best meets the needs of real professionals. Many emerging
fields, including mobile, online gaming, server-side, cloud development, data
science, and education, are progressively using Kotlin.
All of this indicates that there is already a high demand for Kotlin developers, and
that demand will continue to grow in the future. Furthermore, if you are looking to
build native Android apps, Kotlin is the language that you should be using.

Kotlin
The Ultimate Guide
Edited by
Sufyan bin Uzayr
First edition published 2023
by CRC Press
6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742
and by CRC Press
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CRC Press is an imprint of Taylor & Francis Group, LLC
© 2023 Sufyan bin Uzayr
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Library of Congress Cataloging-in-Publication Data
Names: Bin Uzayr, Sufyan, author.
Title: Kotlin : the ultimate guide / Sufyan bin Uzayr.
Description: First edition. | Boca Raton : CRC Press, 2023. | Includes
bibliographical references and index.
Identifiers: LCCN 2022025675 (print) | LCCN 2022025676 (ebook) | ISBN
9781032311708 (hardback) | ISBN 9781032311692 (paperback) | ISBN
9781003308447 (ebook)
Subjects: LCSH: Android (Electronic resource) | Kotlin (Computer program
language) | Application software--Development. | Mobile
apps--Development. | Java (Computer program language)
Classification: LCC QA76.73.K68 B56 2023 (print) | LCC QA76.73.K68
(ebook) | DDC 005.1/14--dc23/eng/20220917
LC record available at https://lccn.loc.gov/2022025675
LC ebook record available at https://lccn.loc.gov/2022025676
ISBN: 9781032311708 (hbk)
ISBN: 9781032311692 (pbk)
ISBN: 9781003308447 (ebk)
DOI: 10.1201/9781003308447
Typeset in Minion
by KnowledgeWorks Global Ltd.
Contents
Acknowledgments, xxi
About the Author, xxiii
Chapter 1 ◾ C rash Course in Kotlin 1
KOTLIN PROGRAMMING LANGUAGE HAS A RICH HISTORY 2
FEATURES OF THE KOTLIN PROGRAMMING LANGUAGE 2
KOTLIN PROGRAMMING LANGUAGE APPLICATIONS 4
WHY SHOULD WE STUDY THE KOTLIN PROGRAMMING
LANGUAGE? WHAT ARE THE BENEFITS OF LEARNING
THE KOTLIN PROGRAMMING LANGUAGE? 4
DISADVANTAGES OF KOTLIN 5
WHAT IS THE PURPOSE OF KOTLIN? 5
Android Development 5
Back-End Web Development 6
Full-Stack Web Development 6
Data Science 6
Mobile Development for Several Platforms 7
KOTLIN’S ARCHITECTURE 7
KOTLIN FRAMEWORKS FOR SERVER-SIDE DEVELOPMENT 8
KOTLIN ENVIRONMENT FOR COMMAND LINE SETUP 9
Intellij IDEA IS USED TO BUILD UP A KOTLIN ENVIRONMENT 9
THE FIRST PROGRAM IS WRITTEN IN KOTLIN 11
KOTLIN DATA TYPES 12
Number Data Types in Kotlin 12
Character Data Type in Kotlin 13
v
vi ◾ Contents
String Data Type in Kotlin 14
Boolean Data Type in Kotlin 14
Array Data Type in Kotlin 15
DATA TYPE CONVERSION IN KOTLIN 15
OPERATORS IN KOTLIN 16
Arithmetic Operators in Kotlin 16
Relational Operators in Kotlin 17
Assignment Operators in Kotlin 17
Unary Operators in Kotlin 18
Logical Operators in Kotlin 19
Bitwise Operations in Kotlin 19
BOOLEANS IN KOTLIN 20
Create Boolean Variables 20
Boolean Operators in Kotlin 21
Boolean Expression in Kotlin 21
and() and or() Functions in Kotlin 22
Boolean to String 22
STRINGS IN KOTLIN 22
String Templates in Kotlin 23
String Object in Kotlin 23
String Indexes in Kotlin 23
String Length in Kotlin 24
String Kotlin Last Index 24
String Case Changing 24
String Concatenation in Kotlin 25
Trim Characters from the String 25
Quotes Inside a String 26
Finding a String Inside a String 26
Comparing Two Strings 26
getOrNull() Function in Kotlin 26
toString() Function in Kotlin 27
Contents ◾ vii
ARRAYS IN KOTLIN 27
Creating Arrays 27
Arrays of the Primitive Type 28
Elements of an Array Can Be Get and Set 28
Array Length in Kotlin 28
Loop through an Array 29
Check if an Element Exists 29
Distinct Values from the Array 29
Dropping Elements from the Array 30
Checking an Empty Array 30
RANGES IN KOTLIN 30
Creating Ranges Using the rangeTo() Function 31
Creating the Ranges Using the .. Operator 31
Creating the Ranges Using downTo() Operator 31
step() Function in Kotlin 32
Range of Characters in Kotlin 32
reversed() Function in Kotlin 32
until() Function in Kotlin 32
The last, first, and step Elements 33
Filtering Ranges 33
Distinct Values in Range 33
Range Utility Functions 34
FUNCTIONS IN KOTLIN 34
Built-in Functions in Kotlin 34
User-Defined Functions 34
Function Parameters 35
Return Values 35
Unit-Returning Functions 36
Recursive Function in Kotlin 36
Tail Recursion in Kotlin 37
Higher-Order Functions 38
viii ◾ Contents
Lambda Function in Kotlin 38
Inline Function in Kotlin 38
If-else EXPRESSION IN KOTLIN 39
if Statement 39
if-else Statement 40
if-else Expression in Kotlin as the Ternary Operator 42
if-else-if Ladder Expression 42
nested if Expression 44
while loop IN KOTLIN 45
do-while loop IN KOTLIN 47
Method of do-while loop 47
for loop IN KOTLIN 48
Iterate across the Range Using a for loop 49
Using a for loop, Iterate over the Array 50
Iterate through a String Using the for loop 51
Iterate over the Collection Using the for loop 52
KOTLIN when expression 52
when to Use as a Statement with else 53
Using when as a Statement in the Absence of an else Branch 53
when Used as an Expression 53
In Kotlin, Different Ways to Use a when Block 54
UNLABELED BREAKS IN KOTLIN 57
In a while loop, Use of an Unlabeled Break 57
In a do-while loop, Use of an Unlabeled Break 58
Use of an Unlabeled Break in a for loop 59
LABELED BREAKS IN KOTLIN 60
In a while loop, Using a Labeled Break 60
In a do-while loop, Using a Labeled Break 61
Using a Labeled Break in a for loop 62
KOTLIN UNLABELED CONTINUE 63
Use of Unlabeled Continues in the while loop 63
Contents ◾ ix
In a do-while loop, Use an Unlabeled Continue 64
Use of Unlabeled Continues in a for loop 64
KOTLIN LABELED CONTINUES 65
Use of Labeled Continues in a while loop 65
Use of Labeled Continues in a do-while loop 66
Use of Labeled Continues in a for loop 67
EXCEPTIONAL HANDLING 68
Exceptions in Kotlin 68
Exception Handling in Kotlin 69
Avoiding NullPointerException 70
What If We Fail to Deal with Exceptions? 70
How to Throw an Exception 70
KOTLIN try-catch block 71
The try-catch block as an Expression in Kotlin 72
The final block in Kotlin 72
Kotlin throw keyword 74
NESTED try block AND MULTIPLE catch block 74
Nested try block 74
Multiple catch block 75
NULL SAFETY 77
Nullable and Non-Nullable Sorts in Kotlin 77
Checking for the null in Conditions 78
Safe Call operator(?.) 79
Elvis Operator(?:) 80
Not null assertion: !! Operator 80
TYPE CHECKING AND SMART CASTING 81
Type Checking 81
Smart Casting 82
Use of !is Operator 83
EXPLICIT TYPE CASTING 83
Unsafe Cast Operator: as 84
Safe Cast Operator: as? 85