Nick Young: Screw Fireworks And Fiancees ... IT'S BACK TO BASKETBALL!!

Here's more proof Nick Young only cares about his balls ... he's already re-ignited his hoops training for next year's NBA season, and TMZ Sports has pics of the Lakers star puttin' in work.

Swaggy's fresh off being dumped by Iggy Azalea, and aired out by his baby mama Keonna Green, but it didn't stop him from hitting up the Sports Academy in Thousand Oaks, CA to work on his J.

Check out the pics -- SA is a MASSIVE training center and Nick seems to use every inch of it ... hitting the weights in addition to getting his shots up.