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


As we already know, a supertype of all Kotlin types is Any. It is the equivalent of the Java Object type. Each Kotlin class explicitly or implicitly extends the Any class. If we do not specify the parent class, Any will be implicitly set as the parent of the class:

    class Plant // Implicitly extends Any 
    class Plant : Any // Explicitly extends Any 

Kotlin, like Java, promotes single inheritance, so a class can have only one parent class, but it can implement multiple interfaces.

In contrast to Java, every class and every method in Kotlin is final by default. This conforms to the Item 17 in Effective Java, the Design and document for inheritance or else prohibit it rule. This is used to prevent unexpected behavior from a subclass changing. Modification of a base class can cause incorrect behavior of subclasses because the changed code of the base class no longer matches the assumptions in its subclasses.

This means that a class cannot be extended and a method cannot be overridden...