create list of String from file names in provided directory

Question

probably my question is rather obvious. Would like to look on the one directory and createthe the List of the String, where each string represents the file name stored in given direcotry, e.g. List("file1.csv", "file2.csv", "file3.csv").

I use the function which creates list, but it's list of Files (not Strings) and includes full paths (not only the file names).

import java.io.File

def getFileNames(path: String): List[File] = {
  val d = new File(path)
  if (d.exists && d.isDirectory) {
    d
      .listFiles // create list of File
      .filter(_.isFile)
      .toList
      .sortBy(_.getAbsolutePath().replaceAll("[^a-zA-Z0-9]",""))
  } else {
    Nil // return empty list
  }
}

Thank you for all the ideas.

Mario Galic · Accepted Answer · 2019-06-26 13:32:09Z

2

Try changing the return type of getFileNames toList[String] and use map(_.getName) like so

def getFileNames(path: String): List[String] = {
    val d = new File(path)
    if (d.exists && d.isDirectory) {
      d
        .listFiles // create list of File
        .filter(_.isFile)
        .toList
        .sortBy(_.getAbsolutePath().replaceAll("[^a-zA-Z0-9]",""))
        .map(_.getName)
    } else {
      Nil // return empty list
    }
  }

Make sure .map(_.getName) is the last in the chain, that is, after sortBy.

better-files would simplify this to

import better.files._
import better.files.Dsl._
val file = file"."
ls(file).toList.filter(_.isRegularFile).map(_.name)

edited Jun 26, 2019 at 13:32

answered Jun 26, 2019 at 13:24

Mario Galic

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Comments

Dionysis Nt. · Accepted Answer · 2019-06-26 13:32:06Z

1

you can use getName method

and as Tomasz pointed out, filter and map can be combined to collect as following

def getFileNames(path: String): List[String] = {
  val d = new File(path)
  if (d.exists && d.isDirectory) {
    d
      .listFiles // create list of File
      .collect{ case f if f.isFile => f.getName }// gets the name of the file  <--
      .toList
      .sortBy(_.getAbsolutePath().replaceAll("[^a-zA-Z0-9]",""))
  } else {
    Nil // return empty list
  }
}

edited Jun 26, 2019 at 13:32

answered Jun 26, 2019 at 13:20

Dionysis Nt.

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2 Comments

Valy Dia Over a year ago

The filter followed by map can be combined using collect collect{ case f if f.isFile => f.getName }

Tomasz Over a year ago

Thanks! A small comment: the output type should be changed to the List[String].

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