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

Coding the database class


Here, we will put into practice everything we have learned so far and finish coding the Age database app. Before our Fragment classes from the previous section can interact with a shared database, we need a class to handle interaction with, and creation of, the database.

We will create a class that manages our database by implementing SQLiteOpenHelper. It will also define some String variables in a companion object to represent the names of the table and its columns. Furthermore, it will supply a bunch of helper functions we can call to perform all the necessary queries. Where necessary, these helper functions will return a Cursor object that we can use to show the data we have retrieved. It would be trivial then to add new helper functions should our app need to evolve:

Create a new class called DataManager and add the companion object, the constructor, and the init block:

Note

We discussed the companion object in Chapter 25, Advanced UI with Paging and Swiping

class...