A note for early adopters of this book

At time of completing this book, Android 9 and Android Studio 3.2 had just been released. This book was written to accommodate these latest versions. One of the changes in the new releases is the way that Android supports devices running older versions of Android. It has just been significantly improved. Android uses a support library, which means that old devices (within reason) can make use of newer features.

The good news is that this book uses the new, improved version!

However, if you are a very early adopter (late 2018 and maybe into early 2019) of this book and you look very closely at the code generated by Android Studio, you will notice some slight differences with the code presented in the book. The differences occur in the import… statements at the top of the Java code files. The book presents code that looks a bit like this:

import androidx.appcompat.app.AppCompatActivity;

Whereas you might notice code in Android Studio 3.2 or earlier that...