Scala filter by extension

Question

I have this function below for filter a list of files. I was wondering how I could filter so it only returns files that end in .png or .txt?

 def getListOfFiles(directoryName: String): Array[String] = {
 return (new File(directoryName)).listFiles.filter(_.isFile).map(_.getAbsolutePath)
}

Thanks for the help, guys.

score 5 · Accepted Answer · edited May 23 '17 at 11:59

5

Just add a condition to filter:

(new File(directoryName)).listFiles.
  filter { f => f.isFile && (f.getName.endsWith(".png") || f.getName.endsWith(".txt")) }.
  map(_.getAbsolutePath)

or use listFiles(FileFilter) instead of just listFiles, but it's less convenient (unless you use experimental Scala single method interface implementation)

edited May 23 '17 at 11:59

Community

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answered Apr 18 '16 at 11:56

Alexey Romanov

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The SAM version would be something like `new File(directoryName).listFiles(file => file.isFile && file.getName.endsWith(".png") || file.getName.endsWith(".png"))` – phw Nov 20 '18 at 16:21

score 0 · Answer 2 · answered Apr 18 '16 at 11:57

0

Just like you would filter ordinary strings:

val filenames = List("batman.png", "shakespeare.txt", "superman.mov")
filenames.filter(name => name.endsWith(".png") || name.endsWith(".txt"))
// res1: List[String] = List(batman.png, shakespeare.txt)

answered Apr 18 '16 at 11:57

om-nom-nom

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score 0 · Answer 3 · answered Jun 24 '20 at 15:19

0

Alternative approach, a bit less verbose

import scala.reflect.io.Directory
Directory(directoryName).walkFilter(_.extension=="png")

It returns an Iterator[Path] which can be converted with.toArray[String]

answered Jun 24 '20 at 15:19

Pierre Gramme

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Scala filter by extension

3 Answers3