disable commands in worlds, and vector help

hello everybody,

I have two problems. the first is, how can I disable a command or an piece of code if a player is in a disabled world. lets say we have a string disabledWorlds, with in there the disabled worlds separated by comma's. I thought this code

Code:

if (!disabledWorlds.contains(player.getLocation().getWorld()))
  // code

where player is a player object of the player who performed the command. but this doesn't work.
please help me

my second question is how I can change a vector to a block face.
I wanna select a block in the front of a player. but not the one he is looking at.
like this (image):
PPP ----------
PPP
PPP
PPP
BBB|BBB|SSS|
BBB|BBB|SSS|

where P is the player, B is a block, - is the players sight and S is the block I wanna select.

I hope you can help me, awesome communitie