Ceiling junction box not hooked up to switch?
If it's a rental, some places will not install overhead fixtures in the bedrooms. There's a couple of ways to play this


Add a surface mount box extender from the existing ceiling box and surface mount wire conduit. Run this to a surface mount switch on the wall and you're set.
Buy some lamp cord, an outlet, and electrical staples that fit said cord. This is not code, but I've taken the cord, run it to where I need to mount the fixture (in my case, into the ceiling), wired it up, stapled it to the wall to keep it out of the way and plugged it into the switched outlet. Because you have both a plug and switch, it's not terribly unsafe (I had a ceiling fan I put in an apartment this way). It's not kosher without a box, tho.