I'm not sure if this goes here, but lets hope so. Okay, so I've started making a game engine, and right now I'm working on the level format. Right now, I have one object to draw tiles based on a file, the player, the main Jframe and main Java object. Now I haven't coded collision with these graphic tiles yet, because I was thinking that I should make another object that reads from a similar file to draw the collision tiles. This way, I could make a tile act different from its default if I need it to (Example: A secret passageway behind a walk-through wall). Only problem: How do I get an object to spawn another object, and how do I get objects to interact with each other? I know these are probably simple questions, and I'm probably just being stupid; but I can't seem to figure it out. Also, if this isn't an efficient way to do things, please let me know. I'm making sure my game has a level editor, so efficiency is very important. Thank you for your time!