file - Parent parent directory in Java

Question

Please explain me, why when i run this code, all is fine and i get parent directory of my classes:

URL dirUrl = PathsService.class.getResource("..");

and when I run this code:

URL dirUrl = PathsService.class.getResource("../..");

I get null in dirUrl.

I try like this: URL dirUrl = PathsService.class.getResource("..//.."); all the same I have a null in dirUrl.

How can I get parent/parent/parent ... directory in Java?

Answer 1

NOTICE:

1. As others have already stated, basing any functionality on the retrieval of some parent directory is a very bad design idea (and one that is almost certain to fail too).
2. If you share more details about what you are trying to achieve (the big picture), someone could probably propose a better solution.

That said, you could try the following code:

import java.nio.file.*;
...
Path path = Paths.get(PathsService.class.getResource(".").toURI());
System.out.println(path.getParent());               // <-- Parent directory
System.out.println(path.getParent().getParent());   // <-- Parent of parent directory

Also note, that the above technic may work on your development environment, but may (and probably will) produce unexpected results when your application is "properly" deployed.