val stream = new java.io.BufferedReader(new java.io.FileReader(new java.io.File("test.csv"))) val buf = Stream.continually(stream.readLine).takeWhile( x => x != null ).map(x => x.replace(",", "\t")).mkString("\n") val bw = new java.io.BufferedWriter(new java.io.FileWriter("hogehoge.tsv")) bw.write(buf) bw.close