Scala - Count number of files in directory with defined file extension

Question

Hi I have a script which batch converts pdfs into a series of images, what I'd like to do is count the total number of files in the directory that have the extension .jpg.

So far I have

for (file <- new File(path).listFiles) {

     /* DO SOMETHING */

}

Is there a compact way of doing this without looping through each file?

Thanks in advance, much appreciated :)

In java you can do this http://stackoverflow.com/a/805504/785966 — dotoree, Mar 01 '12 at 16:58

score 8 · Accepted Answer · answered Mar 01 '12 at 16:56

8

How about:

Option(new File(path).list).map(_.filter(_.endsWith(".jpg")).size).getOrElse(0)

Option(...) acts as a null check and is needed because list and listFiles may return null.

answered Mar 01 '12 at 16:56

Jean-Philippe Pellet

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Learned something new. Thanks. I'd personally break it into 2-3 lines though. I think One-liners are usually harder to read. – Jesse Mar 01 '12 at 22:56

score 0 · Answer 2 · answered Mar 02 '12 at 00:29

0

for (file <- new java.io.File (".").listFiles;
  if (file.getName ().matches (".*\\.scala"))) println (file)

results in:

./TopTen.scala
./QuadTree.scala
./Euler093.scala
./ParallelFactorial.scala
./GenericCartesian.scala

answered Mar 02 '12 at 00:29

user unknown

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Scala - Count number of files in directory with defined file extension

2 Answers2