Recursively create directory

Question

Does anyone know how to use Java to create sub-directories based on the alphabets (a-z) that is n levels deep?

 /a
    /a
        /a
        /b
        /c
           


        

Answer 1

Since Java 7, java.nio is preferred

import java.nio.file.Files;
import java.nio.file.Paths;

...

Files.createDirectories(Paths.get("a/b/c"));

Answer 2

public static void main(String[] args) {
  File root = new File("C:\\SO");
  List<String> alphabet = new ArrayList<String>();
  for (int i = 0; i < 26; i++) {
    alphabet.add(String.valueOf((char)('a' + i)));
  }

  final int depth = 3;
  mkDirs(root, alphabet, depth);
}

public static void mkDirs(File root, List<String> dirs, int depth) {
  if (depth == 0) return;
  for (String s : dirs) {
    File subdir = new File(root, s);
    subdir.mkdir();
    mkDirs(subdir, dirs, depth - 1);
  }
}

mkDirs recusively creates a depth-level directory tree based on a given list of Strings, which, in the case of main, consists of a list of characters in the English alphabet.

Answer 3

You could use three loops over characters a-z like so:

import java.io.*;

public class FileCreate {

    public static void main(String[] args) throws Exception {
        char trunkDirectory = 'a';
        char branchDirectory = 'a';
        char leaf = 'a';

        while (trunkDirectory != '{') {
            while (branchDirectory != '{') {
                while (leaf != '{') {
                    System.out.println(trunkDirectory + "/" + branchDirectory + "/" + leaf++);
                }
                leaf = 'a';
                branchDirectory++;
            }
            branchDirectory = 'a';
            trunkDirectory++;
        }

    }
}

This simply outputs the paths to the console. You could use File#mkdirs() to create a recursive directory structure or create the directories in each intermediate part of the nested loop. I'll leave that for you to finish.

Answer 4

You can simply use the mkdirs() method of java.io.File class.

Example:

new File("C:\\Directory1\\Directory2").mkdirs();

Answer 5

If you're using mkdirs() (as suggested by @Zhile Zou) and your File object is a file and not a directory, you can do the following:

// Create the directory structure
file.getParentFile().mkdirs();

// Create the file
file.createNewFile();

If you simply do file.mkdirs() it will create a folder with the name of the file.

Answer 6

Apache commons addresses most of these. Try -

org.apache.commons.io.FileUtils.forceMkdir(directory);