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

39.4 Testing the Observer

Since the DemoObserver class outputs diagnostic information to the Logcat console, it will be easier to see the output if a filter is configured to display only the DemoObserver messages. Using the steps outlined previously in “Android Activity State Changes by Example”, configure a filter for messages associated with the DemoObserver tag before running the app on a device or emulator.

On successful launch of the app, the Logcat output should indicate the following lifecycle state changes and events:

onCreate

CREATED

onStart

STARTED

onResume

RESUMED

With the app still running, perform a device rotation to trigger the destruction and recreation of the fragment, generating the following additional output:

onPause

STARTED

onStop

CREATED

onDestroy

DESTROYED

onCreate

CREATED

onStart

STARTED

onResume

RESUMED

Before moving to the next section in this chapter, take some time to compare the...