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

    // ensures parent directory is created
    File parentFile = destFile.getParentFile();
    if (parentFile != null && !parentFile.exists()) {
        parentFile.mkdirs();
    }

    // creates destination file
    if (!destFile.exists()) {
        destFile.createNewFile();
    }

Answer 2

If you don't mind relying on a 3rd party API, the Apache Commons IO package does this directly for you. Take a look at FileUtils.ForceMkdir.

The Apache license is commercial software development friendly, i.e. it doesn't require you to distribute your source code the way the GPL does. (Which may be a good or a bad thing, depending on your point of view).

Answer 3

I would write a little utility method that takes the start and the end letter as well as the desired deepth as parameters. This method calls itself recursively till done:

 private static void createAlphabetFolders(File parent, int start, int end, int deepth){

    if(deepth <= 0){
      return;
    }

    for (int i=start; i < end; i++){

      // create the folder
      String folderName = "" + ((char) i);
      File folder = new File(parent, folderName);
      System.out.println("creating: " + folder.getPath());
      folder.mkdirs();

      // call recursively
      createAlphabetFolders(folder, start, end, deepth-1);
    }
  }

One would call it like this:

createAlphabetFolders(new File("abctest"), 'A', 'E', 5);

Answer 4

Scala code:

  def makePathRecursive(path: String) = {
    import java.io.File
    import scala.util.{Try, Failure, Success}

    val pathObj = new File(path)
    pathObj.exists match {
      case true => // do nothing
      case false => Try(pathObj.mkdirs) match {
        case Success(_) => // it worked 
        case Failure(e) => // maybe created meanwhile by another thread
          pathObj.exists match { 
          case false => throw new Exception(e)
          case _ =>  
        }
      }
    }
  }