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

Composite data types

Let's discuss more complex types built into Kotlin. Some data types have major improvements compared to Java, while others are totally new.


Strings in Kotlin behave in a similar way as in Java, but they have a few nice improvements.

To start to access characters at a specified index, we can use the indexing operator and access characters the same way we access array elements:

    val str = "abcd" 
    println (str[1]) // Prints: b 

We also have access to various extensions defined in the Kotlin standard library, which make working with strings easier:

    val str = "abcd" 
    println(str.reversed()) // Prints: dcba 
    println(str.takeLast(2)) // Prints: cd 
    println("[email protected]".substringBefore("@")) // Prints: john 
    println("[email protected]".startsWith("@")) // Prints: false 

This is exactly the same String class as in Java, so these methods are not part of String class. They were defined as extensions. We will learn more about extensions in Chapter 7, Extension...