In this tutorial we’re going to show how to find relative paths between directories using java.nio.file.Path from Java NIO.

Finding relative path between two absolute paths works perfectly fine:

Path path1 = Paths.get("/user1/bin");
Path path2 = Paths.get("/user2/bin");

System.out.printf("Path from %s to %s: %s%n",
    path1, path2, path1.relativize(path2));

The code produces a nice path:

Path from /user1/bin to /user2/bin: ../user2/bin

Path path1 = Paths.get("bin");
Path path2 = Paths.get("doc");
System.out.printf("Path from %s to %s: %s%n",
    path1, path2, path1.relativize(path2));

Calculated path is:

Path from bin to doc: ../doc

try {
    Path path1 = Paths.get("/user1/bin");
    Path path2 = Paths.get("doc");
    path1.relativize(path2);
} catch (IllegalArgumentException e) {
    System.out.printf("Path from %s to %s:%n%s",
        path1, path2, e);
}

Unfortunately the result is IllegalArgumentException:

Path from /user1/bin to doc:
java.lang.IllegalArgumentException: 'other' is different type of Path

When one of the paths is relative and the other one is absolute Path.relativize() will throw the exception with message: ‘other’ is different type of Path.

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