Java: Core GUI Concepts I - Example Program

Well, good to know that TL;DR is a hit! Moving on, GUIs themselves are complicated to teach beyond "Here's the libraries, get to it", so we'll start off with an example program! This should hopefully give us an idea of how certain aspects are used and whatnot.

The example we'll be using is just a window with a button. The button will toggle between 2 text messages, "Hello" and "Goodbye". It's surprisingly complex, so I'll only be doing this for example purposes, so you can see how the code works. Tomorrow, I'll be recreating the program the easy way (I hope), so don't fret if this is ridiculous. Here is the end result: