There is no reliable way to do this in pure Java. Setting the user.dir
property via System.setProperty()
or java -Duser.dir=...
does seem to affect subsequent creations of Files
, but not e.g. FileOutputStreams
.
The File(String parent, String child)
constructor can help if you build up your directory path separately from your file path, allowing easier swapping.
An alternative is to set up a script to run Java from a different directory, or use JNI native code as suggested below.
The relevant OpenJDK bug was closed in 2008 as “will not fix”.