count.scala

import scala.annotation.tailrec
import java.io._

def getFileAndByteCount(srcDir: File) = {
  @tailrec
  def getFileAndByteCountAcc(dirList: Array[File], fileCount: Long, byteCount: Long): Tuple2[Long, Long] = {
    val (files, subDirs) = dirList.partition(_.isFile)
    val classFiles = files.filter(f => f.getName.endsWith(".class"))
    val newFileCount = fileCount + classFiles.size
    val newByteCount = byteCount + classFiles.map { f => f.length.toLong }.foldLeft(0l) { (a, b) => a + b }
    if (subDirs.isEmpty) 
      (fileCount, byteCount)
    else 
      getFileAndByteCountAcc(subDirs.flatMap(d => d.listFiles), newFileCount, newByteCount)
  }
  getFileAndByteCountAcc(srcDir.listFiles, 0l, 0l)
}

val (fileCount, byteCount) = getFileAndByteCount(new File("target/test_classes"))
println("Total files: " + fileCount + ", size: " + byteCount + " bytes.")