This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
mkdirs() will create all parent folders as needed on all platforms, so yes, this will also work on Unix. Well, as long as you have the rights to create the folders of course, but that is also an issue on Windows.