Book Image

Android Programming with Kotlin for Beginners

By : John Horton
5 (1)
Book Image

Android Programming with Kotlin for Beginners

5 (1)
By: John Horton

Overview of this book

Android is the most popular mobile operating system in the world and Kotlin has been declared by Google as a first-class programming language to build Android apps. With the imminent arrival of the most anticipated Android update, Android 10 (Q), this book gets you started building apps compatible with the latest version of Android. It adopts a project-style approach, where we focus on teaching the fundamentals of Android app development and the essentials of Kotlin by building three real-world apps and more than a dozen mini-apps. The book begins by giving you a strong grasp of how Kotlin and Android work together before gradually moving onto exploring the various Android APIs for building stunning apps for Android with ease. You will learn to make your apps more presentable using different layouts. You will dive deep into Kotlin programming concepts such as variables, functions, data structures, Object-Oriented code, and how to connect your Kotlin code to the UI. You will learn to add multilingual text so that your app is accessible to millions of more potential users. You will learn how animation, graphics, and sound effects work and are implemented in your Android app. By the end of the book, you will have sound knowledge about significant Kotlin programming concepts and start building your own fully featured Android apps.
Table of Contents (33 chapters)
Android Programming with Kotlin for Beginners
Contributors
Preface
Index

Getting dynamic with arrays


As we discussed at the beginning of this section, if we need to declare and initialize each element of an array individually, there isn't a huge benefit to using an array over regular variables. Let's take a look at an example of declaring and initializing arrays dynamically.

A dynamic array example

You can get the working project for this example in the download bundle. It can be found in the Chapter15/Dynamic Array Example/MainActivity.kt file.

Create a project with an Empty Activity template and call it Dynamic Array Example.

Type the following code just after the call to setContentView in the onCreate function. See if you can work out what the output will be before we discuss and analyze the code:

// Declaring and allocating in one step
val ourArray = IntArray(1000)

// Let's initialize ourArray using a for loop
// Because more than a few variables is allot of typing!

for (i in 0..999) {

   // Put the value into ourArray
   // At the position decided by i.
...