Kotlin is a relatively new language that is gaining popularity rapidly, thanks to its numerous unique features that increase developer productivity. It is primarily used for mobile (Android) and server-side (backend) development but can be used anywhere Java is used. Thanks to its other compiler, which transforms it into JavaScript, it can even be used for frontend web development. This book targets newcomers to the language and tries to bring them to intermediate-advanced levels of Kotlin knowledge.
This book covers the basic features of the language and its syntax, so no prior knowledge of Kotlin is required. You should have at least basic knowledge of general programming. You should know what control-flow statements, variables, classes, and basic data structures are.
Chapter 1, Introducing Kotlin, covers general features of the language and shows the reader how to install an IDE and the Kotlin compiler.
Chapter 2, Kotlin Basics, introduces the reader to the language syntax and explores the basic building blocks of the language: functions, variables, basic types, and so on.
Chapter 3, Classes and Object-Oriented Programming, focuses on the object-oriented features of the language. The chapter explores classes and interfaces and how they are extended and implemented. The chapter also shows some features that are specific to Kotlin, such as objects, companion objects, and sealed classes.
Chapter 4, Functions and Lambdas, shows how functions are first-class citizens in Kotlin. The chapter also shows Kotlin function features that are not present in Java, such as default argument values, named parameters, and function inlining.
Chapter 5, Advanced Kotlin, deals with more advanced features of Kotlin, such as operator overloading, generics, receiver functions, and constructs for multi-threaded programming.
Chapter 6, Kotlin Standard Library, shows some really useful functions that ship with Kotlin and also explores the Collections API.
Chapter 7, Coding a Dictionary App with Kotlin, is the chapter where we put Kotlin into practice. We summarize our learning from previous chapters and build a desktop dictionary application.
Since Kotlin compiles to Java bytecode and uses Java's types and build tools (Maven and Gradle), readers with a Java background will probably find Kotlin a bit easier than those without. But a Java background is not a requirement, as this book is intended for readers who are completely new to Kotlin/Java and the JVM ecosystem.
This book doesn't teach programming, so readers that have knowledge of any modern general-purpose programming language will find content in this book more understandable than those who don't.
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There are a number of text conventions used throughout this book.
CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Mount the downloaded WebStorm-10*.dmg disk image file as another disk in your system."
A block of code is set as follows:
<plugin>
<artifactId>kotlin-maven-plugin</artifactId>
<groupId>org.jetbrains.kotlin</groupId>
<version>${kotlin.version}</version>
<configuration>
<jvmTarget>1.8</jvmTarget>
</configuration>
</plugin>Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Select System info from the Administration panel."
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