System property user.dir

in the Java API guide (http://java.sun.com/j2se/1.5.0/docs/api/java/io/
File.html) the docs mention a system property user.dir that supposedly
has the current user directory.

How do I access the value in this property?

Alternately, is there another way I can establish a base directory
such that, in a subdirectory of my package/jar, I can store data for
the application to read?

Eg. if my application is running in C:x\y\z, I'd like to have a
directory whose fully-qualified name is C:x\y\z\data. If the
application is transported and later runs on D:\a\b\c\, I'd like that
directory to resolve to D:\a\b\c\data.

Thanks.

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