Java around the world

Ok I know it's a really weird question but I'm working on a project which will use a translucent program "floating" on top of the desktop and any active windows. I want the translucent window to stay on top and covering the entire desktop but still be able to use the windows and desktop below. First: Can this be done in Java? If so, how? and if not, can it be done with some other programming language? If it needs to be in another language that's fine but Java is the only one I know (for now) so I would need links to very specific instructions or premade software.