Learn Kotlin Programming Second Edition

<Learn Kotlin Programming Second Edition> ▶Book Description
Kotlin is a general-purpose programming language used for developing cross-platform applications. Complete with a comprehensive introduction and projects covering the full set of Kotlin programming features, this book will take you through the fundamentals of Kotlin and get you up to speed in no time.

Learn Kotlin Programming covers the installation, tools, and how to write basic programs in Kotlin. You'll learn how to implement object-oriented programming in Kotlin and easily reuse your program or parts of it. The book explains DSL construction, serialization, null safety aspects, and type parameterization to help you build robust apps. You'll learn how to destructure expressions and write your own. You'll then get to grips with building scalable apps by exploring advanced topics such as testing, concurrency, microservices, coroutines, and Kotlin DSL builders. Furthermore, you'll be introduced to the kotlinx.serialization framework, which is used to persist objects in JSON, Protobuf, and other formats.

By the end of this book, you'll be well versed with all the new features in Kotlin and will be able to build robust applications skillfully.

▶What You Will Learn
- Explore the latest Kotlin features in order to write structured and readable object-oriented code
- Get to grips with using lambdas and higher-order functions
- Write unit tests and integrate Kotlin with Java code
- Create real-world apps in Kotlin in the microservices style
- Use Kotlin extensions with the Java collections library
- Uncover destructuring expressions and find out how to write your own
- Understand how Java-nullable code can be integrated with Kotlin features

▶Key Features
- Learn the fundamentals of Kotlin to write high-quality code
- Test and debug your applications with the different unit testing frameworks in Kotlin
- Explore Kotlin's interesting features such as null safety, reflection, and annotations

▶Who This Book Is For
If you're a beginner or intermediate programmer who wants to learn Kotlin to build applications, this book is for you. You'll also find this book useful if you're a Java developer interested in switching to Kotlin.

▶What this book covers
- Chapter 1, Getting Started with Kotlin, covers how to install Kotlin, the Jetbrains Intellij IDEA, and the Gradle build system. Once the setup of the tool chain is complete, the chapter shows how to write your first Kotlin program.

- Chapter 2, Kotlin Basics, dives head first into the basics of Kotlin, including the basic types, basic syntax, and program control flow structures, such as if statements, for loops, and while loops. The chapter concludes with Kotlin-specific additions, such as when expressions and type inference.

- Chapter 3, Object-Oriented Code in Kotlin, focuses on the object-oriented aspects of the language. It introduces classes, interfaces, objects and the relationship between them, as well as subtypes and polymorphism.

- Chapter 4, Functions in Kotlin, shows that functions, also known as procedures or methods, are the basic building blocks of any language. This chapter covers the syntax for functions, including Kotlin enhancements such as named parameters, default parameters, and function literals.

- Chapter 5, Higher-Order Functions and Functional Programming, focuses on the functional programming side of Kotlin, including closures, also known as lambdas, and function references. It also covers functional programming techniques, such as partial application, function composition, and error accumulation.

- Chapter 6, Properties, explains that properties work hand in hand with object-orientated programming to expose values on a class or object. This chapter covers how properties work, how the user can best make use of them, and also how they are represented in the bytecode.

- Chapter 7, Null Safety, Reflection, and Annotations, explains that null safety is one of the main features that Kotlin provides, and the first part of this chapter covers in depth the whys and how's of null safety in Kotlin. The second part of the chapter introduces reflection—runtime introspection of code—and how it can be used for meta programming with annotations.

- Chapter 8, Generics, explains that generics, or parameterized types, are a key component of any advanced type system, and the type system in Kotlin is substantially more advanced than that available in Java. This chapter covers variance, the type system, including the nothing type, and algebraic data types.

- Chapter 9, Data Classes, shows that immutability and boilerplate-free domain classes are a current hot topic, due to the way they facilitate more robust code and simplify concurrent programming. Kotlin has many features focused on this area, which it calls data classes.

- Chapter 10, Collections, explains that collections are one of the most commonly used aspects of any standard library, and Java collections are no different. This chapter describes the enhancements that Kotlin has made to the JDK collections, including functional operations such as map, fold, and filter.

- Chapter 11, Testing in Kotlin, explains that one of the gateways into any new language is using it as a language for writing test code. This chapter shows how the exciting test framework, KotlinTest, can be used to write expressive, human-readable tests, with much more power than the standard JUnit tests allow.

- Chapter 12, Microservices in Kotlin, shows that microservices have come to dominate serverside architecture in recent years, and Kotlin is an excellent choice for writing such services. This chapter introduces the Lagom microservice framework and shows how it can be used to great effect with Kotlin.

- Chapter 13, Concurrency, explains that, as multicore-aware programs are becoming more and more important in server-side platforms, this chapter is focused on a solid introduction to concurrent programming techniques that are vital in modern development, including threads, concurrency primitives, and futures.

- Chapter 14, Coroutines, covers the powerful Kotlin concurrency library known as coroutines that enable thread-safe code to be written in a simple, imperative way. This chapter focuses on introducing the core constructs of coroutines, how they work, and perhaps, most importantly, why they are useful.

- Chapter 15, Application of Coroutines, focuses on real-world scenarios and use cases of coroutines. This chapter expands on the previous chapter, covering use cases such as producers and consumers, channels, debugging in a multithreaded context, and how to bridge normal threaded code with the coroutine world.

- Chapter 16, Kotlin Serialization, introduces a compiler plugin, written by Jetbrains, that generates serialization and deserialization functions for Kotlin classes that do not use runtime reflection for introspection. This results in more performant code. This chapter also includes information on several different serialization formats available for this library.