CODEWITHSUNDEEP
javafile
Gaurav Sinha
Gaurav Sinha

Reputation: 21

Files API to get all symbolic links for a folder

Folder17
Folder18
Folder19 -> /myfolder/17
Folder20 -> /myfolder/17

I have a created symbolic link from Folder19 to Folder17 and Folder 20 to Folder17

I can use Files.isSymbolicLink(path) to find whether file is symbolic linked. But is there another way around ? I wanted to know all the folders linked to me. Like, in this case, I want to know all links for Folder17 which should give me Folder19 and Folder20

I created below have something like below cd /foo

mkdir b
ln -s /foo/b e
ln -s /foo/b f
ln -s /foo/b g
ls -la
    b
    e -> /foo/b
    f -> /foo/b
    g -> /foo/b

In my java class, I did below.I was expecting to return e,f,g with size 3. But the size is 0

    Path path = Paths.get("/foo/b");
    Collection<Path> paths      =  Files.walk(path)
            .filter(Files::isSymbolicLink)
            .filter(p -> {
                try {
                    return path.equals(Files.readSymbolicLink(p));
                } catch (IOException e) {
                    System.out.println("log");
                    throw new RuntimeException("An I/O error has occurred!");
                }
            })
            .collect(Collectors.toList());
    System.out.println(paths.size());
}
catch(Exception e)
{
    e.printStackTrace();
}

}

Upvotes: 2

Views: 539

Answers (1)

Jacob G.
Jacob G.

Reputation: 29700

Good question. You can probably see why it would be redundant for some file A to track every file that is symbolically-linked to A, as that could potentially take up a large amount of space. For that reason, it would be simple to navigate through the directory, checking for symbolic links to file A. You can use something similar to the following:

Files.walk(path)
     .filter(Files::isSymbolicLink)
     .filter(p -> {
         try {
             return path.equals(Files.readSymbolicLink(p));
         } catch (IOException e) {
             throw new RuntimeException("An I/O error has occurred!");
         }
     })
     .collect(Collectors.toList());

This returns a List<Path> containing all of the Paths which are symbolic links to path.

Note: You can use Files#walkFileTree to recursively search through these directories if needed.

Upvotes: 3

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