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

Lambdas


When a RadioButton widget is part of RadioGroup, the visual appearance of them is coordinated for us. All we need to do is react when any given RadioButton widget is pressed. Of course, as with any other button, we need to know when they have been clicked on.

A RadioButton widget behaves differently to a regular Button widget and simply listening for clicks in onClick (after implementing OnClickListener) will not work because the RadioButton class is not designed that way.

What we need to do is use another Kotlin feature. We need an instance of a special interface, for the sole purpose of listening for clicks on RadioGroup. The next block of code assumes that we have a reference to a RadioGroup instance called radioGroup; here is the code to examine:

radioGroup.setOnCheckedChangeListener {
   group, checkedId ->
   // Handle the clicks here
}

The preceding code, specifically setOnChekedChangeListener from its opening curly brace ({) to the closing curly brace (}), is what is known...