Are you like joking? Java and native Swing? I thought that this was made with the libGDX or JavaFX at least. Anyway, this is extremely well done. How much time did you spend on this project?
The school project spanned over 9 weeks, but it was secondary as we were busy with full time classes and other more important projects / exams, so we mostly worked on it in the evenings or during vacation. I was personally extra-invested into it, so I tracked my hours of work during that time and have 200 hours on record.
After that, I took some extra time during summer vacation to add sound effects and implement some scrapped features, but I was very inconsistent and scattered in my work (+ didn't use a tracker) so I wouldn't know how to estimate the actual amount of time that took :>