Java find and replace path

Question

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?

Strings are actually pretty portable, however to avoid them you can use .getParent().getParent().getParent().getParent().resolve(newDirName).resolve(...) — Bohemian
– Bohemian ♦, Commented Sep 15, 2020 at 6:45

Andreas · Accepted Answer · 2020-09-15 06:49:59Z

2

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

answered Sep 15, 2020 at 6:49

Andreas

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Antoniossss · Accepted Answer · 2020-09-15 06:46:28Z

2

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

answered Sep 15, 2020 at 6:46

Antoniossss

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