Java find and replace path

Is it possible to find and replace in a Path object without converting it to a String?

For example here is a simple code snippet,

import java.nio.file.Path;
import java.nio.file.Paths;

public class Main {

  public static void main(String[] args)  {

    final Path wholePath = Paths.get("/usr/animals/data/donkey/folder1/folder2/data.txt");
    final Path find = Paths.get("/usr/animals/data/donkey");
    final Path replace = Paths.get("/usr/animals/data/sym4");

    Path expected = Paths.get("/usr/animals/data/sym4/folder1/folder2/data.txt"); // how to get this?

    Path path = Paths.get(wholePath.toString().replace(find.toString(), replace.toString()));

    System.out.println(expected.equals(path));
  }
}
     

Using a .toString() method seems to be a non-portable way and instead it's better to use the .resolve() or similar method?

Any suggestions?

Yes, you can do it using Files API, but it will just not be in single step.

    final Path wholePath = Paths.get("/usr/animals/data/donkey/folder1/folder2/data.txt");
    final Path find = Paths.get("/usr/animals/data/donkey");
    final Path replace = Paths.get("/usr/animals/data/sym4");

    //here comes 2 lines of magic
    Path relativized = find.relativize(wholePath);
    Path path = replace.resolve(relativized);
    

    Path expected = Paths.get("/usr/animals/data/sym4/folder1/folder2/data.txt");

    System.out.println(expected.equals(path));

This basicly splits wholePath to "what will be replaced" and "what is left" as relativized. Then it resolves relativized path using new root

In your example, you are not actually finding and replacing, you are re-basing the path, i.e. you are changing the prefix of the path.

To do that, you first convert the input, i.e. wholePath, which is an absolute path, to a relative path, relative to the old root path, i.e. find, so you get folder1/folder2/data.txt, then you resolve that against the new root path, i.e. replace.

You do that by calling relativize(Path other) and resolve(Path other), like this:

Path input = Paths.get("/usr/animals/data/donkey/folder1/folder2/data.txt");
Path oldRoot = Paths.get("/usr/animals/data/donkey");
Path newRoot = Paths.get("/usr/animals/data/sym4");

Path relativePath = oldRoot.relativize(input);
Path result = newRoot.resolve(relativePath); // /usr/animals/data/sym4/folder1/folder2/data.txt