Book Image

Android Studio 4.0 Development Essentials - Java Edition

By : Neil Smyth
Book Image

Android Studio 4.0 Development Essentials - Java Edition

By: Neil Smyth

Overview of this book

Android rolls out frequent updates to meet the demands of the dynamic mobile market and to enable its developer community to lead advancements in application development. This book focuses on the updated features of Android Studio (the fully integrated development environment launched by Google) to build reliable Android applications using Java. The book starts by outlining the steps necessary to set up an Android development and testing environment. You’ll then learn how to create user interfaces with the help of Android Studio Layout Editor, XML files, and by writing the code in Java. The book introduces you to Android architecture components and advanced topics such as intents, touchscreen handling, gesture recognition, multi-window support integration, and biometric authentication, and lets you explore key features of Android Studio 4.0, including the layout editor, direct reply notifications, and dynamic delivery. You’ll also cover Android Jetpack in detail and create a sample app project using the ViewModel component. Finally, you’ll upload your app to the Google Play Console and handle the build process with Gradle. By the end of this book, you’ll have gained the skills necessary to develop applications using Android Studio 4.0 and Java.
Table of Contents (88 chapters)
88
Index

37.1 Understanding ViewModel State Saving

As outlined in the previous chapters, the ViewModel brings many benefits to app development, including UI state restoration in the event of configuration changes such as a device rotation. To see this in action, run the ViewModelDemo app (or if you have not yet created the project, load into Android Studio the ViewModelDemo_LiveData project from the sample code download that accompanies the book).

Once running, enter a dollar value and convert it to euros. With both the dollar and euro values displayed, rotate the device or emulator and note that, once the app has responded to the orientation change, both values are still visible.

Unfortunately, this behavior does not extend to the termination of a background app process. With the app still running, tap the device home button to place the ViewModelDemo app into the background, then terminate it by opening the Logcat tool window in Android Studio and clicking on the terminate button as...