[체험판] Programming Kotlin

▶Book Description
Kotlin has been making waves ever since it was open sourced by JetBrains in 2011; it has been praised by developers across the world and is already being adopted by companies. This book provides a detailed introduction to Kotlin that shows you all its features and will enable you to write Kotlin code to production.

We start with the basics: get you familiar with running Kotlin code, setting up, tools, and instructions that you can use to write basic programs. Next, we cover object oriented code: functions, lambdas, and properties - all while using Kotlin's new features.

Then, we move on to null safety aspects and type parameterization. We show you how to destructure expressions and even write your own. We also take you through important topics like testing, concurrency, microservices, and a whole lot more. By the end of this book you will be able to compose different services and build your own applications.

▶What You Will Learn
- Use new features to write structured and readable object-oriented code
- Find out how to use lambdas and higher order functions to write clean, reusable, and simple code
- Write unit tests and integrate Kotlin tests with Java code in a transitioning code base
- Write real-world production code in Kotlin in the style of microservices
- Leverage Kotlin's extensions to the Java collections library
- Use destructuring expressions and find out how to write your own
- Write code that avoids null pointer errors and see how Java-nullable code can integrate with features in a Kotlin codebase
- Discover how to write functions in Kotlin, see the new features available, and extend existing libraries
- Learn to write an algebraic data types and figure out when they should be used

▶Key Features
- Get a thorough introduction to Kotlin
- Learn to use Java code alongside Kotlin without any hiccups
- Gain a complete overview of null safety, Generics, and many more interesting features

▶Who This Book Is For
This book is aimed those who have little or no Kotlin experience and wish to learn the language quickly. The focus of the book is on server-side development in Kotlin and would be best suited to a developer who is currently a server-side developer or who wishes to learn. No prior knowledge of functional or object-orientated programming is required, but knowledge of some other programming language is recommended.

Some chapters contain brief sections comparing Java implementations to their Kotlin cousins, but these pages can be skipped by those who have no prior Java knowledge.

▶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-orientated aspects of the language. It introduces classes, interfaces, objects and the relationship between them, 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 the 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 further 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 hows of null safety in Kotlin. The second part of the chapter introduces reflection--run time 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 boiler-plate 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 multi-core 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.