Android 9 Development Cookbook - Third Edition

How to do it...

To demonstrate handling the Fragment back stack, we'll create two fragments with a Next button to create a back stack. With that setup, we'll implement the onBackPressed() callback to exit the app when the user reaches the top Fragment. We'll be using the Fragment Manager from the support library, so be sure to choose the support library version when prompted for the import library. We'll need two layout files - one for each fragment - along with two fragment classes. Here are the steps in detail:

1. Create a new layout file called fragment_one.xml with the following XML:

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_height="match_parent"    android ...