Book Image

Kotlin Quick Start Guide

By : Marko Devcic
Book Image

Kotlin Quick Start Guide

By: Marko Devcic

Overview of this book

Kotlin is a general purpose, object-oriented language that primarily targets the JVM and Android. Intended as a better alternative to Java, its main goals are high interoperability with Java and increased developer productivity. Kotlin is still a new language and this book will help you to learn the core Kotlin features and get you ready for developing applications with Kotlin. This book covers Kotlin features in detail and explains them with practical code examples.You will learn how to set up the environment and take your frst steps with Kotlin and its syntax. We will cover the basics of the language, including functions, variables, and basic data types. With the basics covered, the next chapters show how functions are first-class citizens in Kotlin and deal with the object-oriented side of Kotlin. You will move on to more advanced features of Kotlin. You will explore Kotlin's Standard Library and learn how to work with the Collections API. The book finishes by putting Kotlin in to practice, showing how to build a desktop app. By the end of this book, you will be confident enough to use Kotlin for your next project.
Table of Contents (15 chapters)
Title Page
Copyright and Credits
Dedication
Packt Upsell
Contributors
Preface
Index

Basic types


If you are familiar with Java, then you probably know that Java has primitive (value) types and reference types.

The differences between them are that primitive type variables store the actual value of the type in their memory location (usually on the Stack) and reference type variables store the reference (memory address) to another memory location (on the Heap) where the actual data is stored.

Primitive types in Java also have their Boxed (Boxing is an automatic conversion of a primitive type to a reference type) version, a reference type. For example, a primitive int (32-bit integer) has a reference type in type Integer.

Kotlin doesn’t have this distinction between primitive and reference type. This doesn’t mean a Kotlin compiler cannot emit primitive types in Java bytecode. In fact, it would be really inefficient if Kotlin had only reference types.

Kotlin only hides this distinction from a developer. The compiler emits Java bytecode according to usage. In most cases, it will...