Keeping Track of Skill Practice Hours (A JSON, JAVA Project)

I've been wanting to write program that allowed me to keep track of my practice hours for various computer related skills. Some years ago, I read a book by Malcom Gladwell that examined experts of various fields from athletics to music. Each of these experts had practiced their craft for at least an estimated10,000 hours. Eventually, I will surely reach this number with crafts like programming, but it would be hard to say when if I wasn't actually keeping track. So I wrote an interactive program to do just that.

I called it 'Keeper', and it's freely available to download on my GitHub if you want to check it out. 

How it Works: Keeper uses what I called 'trackers' to record events for specified skills. In the source, you'll notice that I used mostly computer languages as the skills you could track. This is a limitation of the example code, but in practice, you would not be limited to the number of trackable skills currently available. Once you've entered data, you could perform analysis and get the following data:

1. What year did I practice X the most/least
2. What time of day did I practice X the most/least
3. Which skill did I practice the most/least
4. etc

I really enjoyed this project, but when I showed it to a friend, they asked why I wouldn't just use Excel to do the same thing. I didn't have a good answer, so I have since switched over to using Excel. The project still serves as a couple good examples of using JSON to serialize, deserialize data.