I'm making a tower defence game in Java!
It's my first game development.
I want to know how many threads Do I need to create in a game, to split logic..
I've made this one:

• 1. Main App thread
     (adds component thread - add(screen))
     

     • 1.1.1 Thread (graphic updates)

     • 1.1.2 Bullets physic

     • 1.1.3 Mobs physic

     • 1.1.4 Towers physic
       

Is it normal to split this logic?