Source code for an Android ViewPager example (Activity and Fragment)

This is a little unusual for me, but I'm putting the following code here so I can remember how I implement a ViewPager in my current Android application. I want to put this code out here in its current state before it gets more complicated. In fact, I only wish I had copied it out here earlier, before I made it as complicated as it is.

The only things that are important to know are: