"The purpose of education is to make good human beings with skills and expertise. Real education enhances the dignity of a human being and increases his or her self-respect. If only the real sense of education could be realized by each individual and carried forward in every field of human activity, the world will be so much a better place to live in."
— Dr. APJ Abdul Kalam
Over 2 billion Android users are active daily, and this reach of data to billions across the globe provides a real opportunity to make a difference. A phone, which was just a device for voice communication until recently, is notjust a phone anymore. Enabling and empowering the next billion users of Android devices will play a significant role in the future.
The purpose of technology is to enable humanity, and the availability of powerful devices provides the opportunity for innovations and can improve the lives of people through technology. Whether it is an app that is built for farmers that provides useful information about the weather or prices of crops, or an app that is built for children with special needs to express themselves, or an app that is built for economically challenged women to run a small home-based business, the opportunities ahead are plenty and very exciting.
This book aims to enable developers who would like to explore the power of Android and experience and enjoy the journey of building Android applications. The chapters have been organized to enable fresh developers to understand and start from the basics, or if you are an experienced developer, to get ahead and explore the power of Kotlin.
To make things much more interesting and easy on this app development journey, Google has added Kotlin as one of the official languages for Android application development. Kotlin is expressive, concise, and powerful. It also ensures seamless interoperability with existing Android languages such as Java and the runtime.
This book will be useful for anyone who is starting fresh on Android application development. Learning Android app development has never been this exciting, as we have more than one choice language being officially supported by Google. This book covers all the details required for Android app development using Kotlin, one step at a time, and enables readers to experience the journey as they make progress.
This book will also certainly help those who are already into Android application development using Java and trying to switch over to Kotlin or evaluate the ease of use of Kotlin. Android app developers who are well versed with Java will find the comparisons of code between Java and Kotlin very useful, and will be able to appreciate the power of Kotlin.
The objective of the book has been to ensure that both advanced Android app developers using Java and those starting to learn Android app development enjoy reading the book.
Chapter 1, Setting Up for Android Development, provides step-by-step information on setting up a system for Android app development, listing all details required to get started.
Chapter 2, Configuring Your Environment for Kotlin, details the steps required to configure the environment for Kotlin. Even though the latest and stable version of Android Studio provides Kotlin support out of the box, the information in this chapter will help you configure the development IDE of your choice.
Chapter 3, Data Types, Variables, and Constants, introduces and discusses the details of Kotlin language constructs, such as data types, variables, and constants.
Chapter 4, Classes and Objects, enhances the discussion on language constructs further by providing information on classes and objects and explains how to define and handle them.
Chapter 5, Type Checks and Null Safety, discusses the salient features of Kotlin – type checks and Null Safety. Kotlin eliminates null reference completely by its design.
Chapter 6, Functions and Lambdas, provides information on defining a function and using it in our program. This chapter also discusses Lambdas and provides information on their use.
Chapter 7, Developing Your Location-Based Alarm, discusses the fundamentals of Google's location-based services, using the Google Map API, and customizing a marker on map.
Chapter 8, Working with Google's Location Services, shows how to build apps using location-based services and explains how to build our own location-based alarm.
Chapter 9, Connecting the Outside World – Networking, covers the concepts of networking and communication with the outside world. We discuss the out-of-the-box options Android framework provides, as well third-party libraries such as Picasso and Glide.
Chapter 10, Developing a Simple To-Do List App, discusses building a user interface using Android Studio and provides information on working with ListViews and Dialogs.
Chapter 11, Persisting with Databases, provides a brief introduction on relational databases, discusses CRUD operations on SQLite in detail, and looks at the use of ORMs, specifically the Room ORM from Google.
Chapter 12, Setting Reminders for Tasks, discusses setting up and pushing notifications to users from our app. It also explains how to utilize cloud services such as Firebase and Amazon SNS. We also discuss services and broadcast receivers.
Chapter 13, Testing and Continuous Integration, discusses the importance of testing, the out-of-the-box support provided by Android Studio through Android Testing Support Library, how to use Crashlytics to track crash reports, and beta testing. This chapter also provides an introduction to CI and provides detailed steps on the use of tools such as Jenkins, Bamboo, and Fastlane.
Chapter 14, Making Your App Available to the World, explains how to publish your app to Google Play Store and Amazon App Store.
Chapter 15, Building an App Using the Google Faces API, discusses the use of the Google Faces API and how to build applications using it. This chapter also provides information on creating Paint instances and using a canvas to draw images. This chapter also discusses drawing shapes such as rectangles on the image.
Having knowledge of object-oriented programming and the Android activity lifecycle will be useful, but is not mandatory.
The latest stable version of Android Studio (version 3.1.3 at the time of publishing) provides support for Kotlin out of the box.
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