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

Using inheritance with open classes


Some terminology that would be useful to learn at this point is that the class that is inherited from is known as the super or base class. Other common ways to refer to this relationship is parent and child class. The child class inherits from the parent class.

By default, a class cannot be inherited from. It is called a final class – not open for extending or inheriting from. It is very straightforward, however, to change a class so it can be inherited from. All we need to do is add the open keyword to the class declaration.

Basic inheritance examples

Look at this next code, which uses the open keyword with the class declaration and enables the class to be inherited from:

open class Soldier() {

    fun shoot () {
        Log.i("Action","Bang bang bang")
    }
}

Note

All the examples from this chapter can be found as completed classes in the Chapter11/Chapter Examples folder.

We can now go ahead and create objects of the Soldier type and call the shoot function...