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

Type inference

As we saw in previous examples, unlike Java, the Kotlin type is defined after the variable name:

    var title: String 

At first glance, this may look strange to Java developers, but this construct is a building block of a very important feature of Kotlin called type inference. Type inference means that the compiler can infer type from context (the value of an expression assigned to a variable). When variable declaration and initialization is performed together (single line), we can omit the type declaration. Let's look at the following variable definition:

    var title: String = "Kotlin" 

The type of the title variable is String, but do we really need an implicit type declaration to determine variable type? On the right side of the expression, we have a string, Kotlin and we are assigning it to a variable, title, defined on the left-hand side of the expression.

We specified a variable type as String, but it was obvious, because this is the same type as the type of assigned expression...