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

Generics


We've already seen generics in previous chapters, and in this section, we'll learn how they work, how they are implemented, and what the differences are from generics in Java.

Simply put, generics are types with parameters. Take a look at the List interface, for example; without generics, you could add objects of any type to it. But, since the list interface is generic, you have to specify a generic type for when you are creating an instance of it. You can create a list of strings, a list of integers, and so on. This then makes the list type-safe; you cannot add an integer to a list of strings.

The generic type is specified in angle brackets, so a list of strings type is declared like this:

List<String> 

Creating an instance of a generic type is the same as creating normal types; you call a generic class constructor and specify the generic type argument:

val strings: List<String> = ArrayList<String>()

Type inference works with generics also, so supplying the generic...