Beginning Kotlin : build applications with better code, productivity, and performance

This book introduces the Kotlin programming skills and techniques necessary for building applications. You'll learn how to migrate your Java programming skills to Kotlin, a Java Virtual Machine (JVM) programming language. The book starts with a quick tour of the Kotlin language and gradually walks you through the language in greater detail over the course of succeeding chapters. You'll learn Kotlin fundamentals like generics, functional programming, type system, debugging, and unit testing. Additionally, with the book's freely downloadable online appendices, you'll discover how to use Kotlin for building Spring Boot applications, data persistence, and microservices. What You Will Learn Learn the Kotlin language, its functions, types, collections, generics, classes, and more Dive into higher-order functions, generics, debugging, and unit testing Apply the fundamentals of Kotlin to Spring Boot Add Hibernate to your Spring Boot application for persistence and data accessibility Take advantage of functional programming available in Kotlin Who This Book Is For Java developers who are new to Kotlin and want to leverage Kotlin, particularly for building Spring Boot apps. Contents About the Author About the Technical Reviewer Acknowledgments Introduction Chapter Overviews Source Code and Supplementary Material Chapter 1: Introduction to Kotlin About Kotlin It’s Simple It’s Asynchronous It’s Object-Oriented It’s Functional Ideal for Tests Setup and Configuration of IntelliJ Hardware Requirements On Windows On macOS On Linux Getting a Project Up and Running Key Takeaways Chapter 2: A Quick Tour of Kotlin Program Elements Literals Variables Expressions and Statements Keywords Whitespace Operators Blocks Comments Basic Types Numbers and Literal Constants Characters Booleans Arrays Strings and String Templates Controlling Program Flow Using ifs The when Statement The while Statement for Loops Exception Handling Handling Nulls Key Takeaways Chapter 3: Functions Declaring Functions Single Expression Functions Default Arguments Named Parameters Variable Number of Arguments Extension Functions Infix Functions Operator Overloading Key Takeaways Chapter 4: Types Interfaces Diamond Problem Invoking Super Behavior Classes Constructors Inheritance Properties Data Classes Visibility Modifiers Inheritance Modifiers Object Declarations Key Takeaways Chapter 5: Higher Order Functions and Lambdas Higher Order Functions Lambda and Anonymous Functions Parameters in Lambda Expressions Closures with and apply Key Takeaways Chapter 6: Collections Arrays Collections Lists Sets Maps Collections Traversal Filter and Map Key Takeaways Chapter 7: Generics Why Generics Terminologies Using Generics in Functions Using Generics in Classes Variance Reified Generics Key Takeaways Chapter 8: Debugging Errors Runtime and Logic Errors Working the Debugger Set Breakpoints Run the Program in Debug Mode Analyze the Program State Other Uses of the Debugger Changing the Program State Key Takeaways Chapter 9: Unit Testing Create the First Test Write the Test Body Run the Test Iterate Key Takeaways Chapter 10: Writing Idiomatic Kotlin Null Checks and Safe Casts Data Classes Named and Default Arguments Named Parameters Expressions apply() Extension Functions Key Takeaways Chapter 11: Creating a Spring Boot Project Spring and Spring Boot The Spring Family Spring Initializr Key Takeaways Index