I found there were plenty of hangers in the closets. Some people have complained in the past that there weren't enough. If you're considering taking a garment bag, a few hangers there should be more than enough.
Tons of them! They are usually the type that will either fit only the rack bar in these closets or they are of the type that fit into a plastic hook that is attached to the bar. This way the previous passenger cannot take all the hangers and leave you without any. We go carry our formals and coats and gowns all on their own hangers in a garment bag but I also pack lots of pants and shirts as does my wife in the luggage and hang them up once we get onboard. Always lots of hangers