How do i retrain a cat to stay out of my room?

I just moved into a friend's apartment and am sleeping in her room where her cats used to be allowed. I'm allergic and don't want them in there. I close my door , but sometimes they run past me into the room and hide or scratch at the door at night. How can I retrain them that it's NOT OK to enter?

with a spray of water

Buy a reall big dog.

cats love to explure the best way to keep a cat out is to make it boring for hie/her no place to hide nothing to do kitty will look elsewhere for fun.

Keep a spray bottle handy. It has kept my cat trained in new places quite often

Have a water gun ready. Orange peel also works. I don't know if leaving orange peel at the door would work, but cats hate oranges.

Closing the door is the only real way. Cat's will want to go places where they can't. You just have to deal with their methods, but you are higher up on the food chain.My cat is not allowed in my guest room, and that is the one place he wants to go the most. I just keep the door closed, and ignore the pawing at the door.

You spray them with a mister

You'll have to keep your door closed and to keep them from scratching the door you may need to get a pet "keep off" spray to spray on the door. The spray is supposed to deter pets from getting on furniture and out of certain areas and can be found at most local pet shops. Of course, cats own a territory and will not willingly be kept out of specific areas once they've been allowed there. They will always try to go in for the rest of their lives. Also, I also have cat allergies and just so you know, dander stays in carpet and on the walls for 5 years. You should scrub the walls and hopefully you have hardwood floors, if not, get rid of that carpet cuz cleaning it won't get rid of the dander!

hot peppers!

a squirt with a water spay bottle is most effective.get allergy shots or pills frm a doctor

You could also try using sticky paws along the space under the door. When they try to run in they'll get stuck and sticky (which cats hate), and they will likely associate that experience with entering the room.