Book Image

Android Development with Kotlin

By : Igor Wojda, Marcin Moskala
Book Image

Android Development with Kotlin

By: Igor Wojda, Marcin Moskala

Overview of this book

Nowadays, improved application development does not just mean building better performing applications. It has become crucial to find improved ways of writing code. Kotlin is a language that helps developers build amazing Android applications easily and effectively. This book discusses Kotlin features in context of Android development. It demonstrates how common examples that are typical for Android development, can be simplified using Kotlin. It also shows all the benefits, improvements and new possibilities provided by this language. The book is divided in three modules that show the power of Kotlin and teach you how to use it properly. Each module present features in different levels of advancement. The first module covers Kotlin basics. This module will lay a firm foundation for the rest of the chapters so you are able to read and understand most of the Kotlin code. The next module dives deeper into the building blocks of Kotlin, such as functions, classes, and function types. You will learn how Kotlin brings many improvements to the table by improving common Java concepts and decreasing code verbosity. The last module presents features that are not present in Java. You will learn how certain tasks can be achieved in simpler ways thanks to Kotlin. Through the book, you will learn how to use Kotlin for Android development. You will get to know and understand most important Kotlin features, and how they can be used. You will be ready to start your own adventure with Android development with Kotlin.
Table of Contents (16 chapters)
Title Page
About the Authors
About the Reviewers
Customer Feedback
Making Your Marvel Gallery Application

Function literals with a receiver

Just as functions have a function type, that allows them to be kept as an object, extension functions have a type that allows them to be kept this way. It is called function type with a receiver. It looks like a simple function type, but the receiver type is located before arguments (like in an extension definition):

    var power: Int.(Int) -> Int

The introduction of a function type with receiver makes full cohesion between functions and types possible, because all functions can now be represented as objects. It can be defined using a lambda expression with a receiver or with an anonymous function with the receiver.

In a lambda expression with a receiver definition, the only difference is that we can refer to a receiver with this, and we can explicitly use receiver elements. For lambda expressions, the type must be specified in a parameter, because there is no syntax to specify receiver type. Here is power defined as a lambda expression with a receiver...