Here it is on a live system. My two variables from the book, true_button and false_button at listed in the file along with hundreds of other definitions from the system.
However, the Android Build doesn’t find them. Everything on my system has been loaded off the Android site in the last 7 days. So, it’s all the latest.
C:\Users\JPL\AndroidStudioProjects\MyApplication5\app\build\generated\not_namespaced_r_class_sources\debug\r\com\example\myapplication5\R.java