Book Image

Android 9 Development Cookbook - Third Edition

By : Rick Boyer
Book Image

Android 9 Development Cookbook - Third Edition

By: Rick Boyer

Overview of this book

The Android OS has the largest installation base of any operating system in the world. There has never been a better time to learn Android development to write your own applications, or to make your own contributions to the open source community! With this extensively updated cookbook, you'll find solutions for working with the user interfaces, multitouch gestures, location awareness, web services, and device features such as the phone, camera, and accelerometer. You also get useful steps on packaging your app for the Android Market. Each recipe provides a clear solution and sample code you can use in your project from the outset. Whether you are writing your first app or your hundredth, this is a book that you will come back to time and time again, with its many tips and tricks on the rich features of Android Pie.
Table of Contents (24 chapters)
Title Page
Copyright and Credits
Dedication
About Packt
Contributors
Preface
Index

Handling the Fragment back stack


In several of the previous recipes, it was mentioned that you should call the addToBackStack() method in the Fragment transaction to enable Android to maintain a Fragment back stack. This is the first step, but may not be enough to provide a rich user experience. In this recipe, we'll explore two other callbacks: onBackPressed() and onBackStackChanged(). As you'll see, by implementing these callbacks, your application can provide specific behavior for the Fragment back stack. The onBackPressed() callback allows the app to check the back stack state and provide custom behavior, such as closing the app when appropriate.

The onBackStackChanged() callback is called whenever the actual back stack changes - such as when a Fragment is popped from the back stack. By overriding this callback, your app can check the current Fragment and update the UI (such as the Home key back arrow) as appropriate.

Getting ready

Create a new project in Android Studio and call it FragmentBackStack...