Use the Files class:
Files.exists(path);
EDIT: to answer your subsequent question, I think the reason that the method is in another class is that Path is an interface, and they wanted to provide an implementation (similar to putting sorting methods in the Collections class instead of the List interface).
Not directly related to the question, but as per ratchet freak there is an optional varags argument to the method as well, which determines how symbolic links are handled
Read the Javadocs from Oracle here.