Book Image

Android Studio Arctic Fox Essentials - Kotlin Edition

By : Neil Smyth
Book Image

Android Studio Arctic Fox Essentials - Kotlin Edition

By: Neil Smyth

Overview of this book

Android Studio is an Integrated Development Environment based on the JetBrains IntelliJ IDEA. It offers developers a unique platform to design and develop Android apps using various developer tools. Fully updated for Android Studio Arctic Fox, the goal of this book is to teach the skills necessary to develop Android-based applications using the Kotlin programming language. This book begins with an outline of the steps necessary to set up an Android development and testing environment, followed by an introduction to programming in Kotlin which includes data types, control flow, functions, lambdas, and object-oriented programming. An overview of Android Studio covers areas such as tool windows, the code editor, and the layout editor tool. An introduction to the architecture of Android is followed by an in-depth look at the design of Android applications and user interfaces using the Android Studio environment. Early chapters detail Android architecture components such as view models, lifecycle management, Room database access, the Database Inspector, app navigation, live data, and data binding. More advanced topics such as intents are also covered, as are touch screen handling, gesture recognition, and the recording and playback of audio. This edition of the book also covers printing, transitions, cloud-based file storage, and foldable device support. The concepts of material design are also discussed in detail, including the use of floating action buttons, Snackbars, tabbed interfaces, card views, navigation drawers, and collapsing toolbars. Other key features of Android Studio Arctic Fox and Android taught in this book include the Layout Editor, the ConstraintLayout and ConstraintSet classes, MotionLayout Editor, view binding, constraint chains, barriers, and direct reply to notifications. Chapters also explore more advanced features of Android Studio such as app links, dynamic delivery, Gradle build configuration, and submitting apps to the Google Play developer console.
Table of Contents (93 chapters)
93
Index

22.2 Default Saving of User Interface State

In the previous chapter, the diagnostic output from the StateChange example application showed that an activity goes through a number of state changes when the device on which it is running is rotated sufficiently to trigger an orientation change.

Launch the StateChange application once again, this time entering some text into the EditText field prior to performing the device rotation (on devices or emulators running Android 9 or later it may be necessary to tap the rotation button in the located in the status bar to complete the rotation). Having rotated the device, the following state change sequence should appear in the Logcat window:

onPause

onStop

onSaveInstanceState

onDestroy

onCreate

onStart

onRestoreInstanceState

onResume

Clearly this has resulted in the activity being destroyed and re-created. A review of the user interface of the running application, however, should show that the text entered into the...