Program that parses a remote XML file containing info about currencies and outputs a new user-defined format for the parsed data in a new file (passed as parameter)

CurrencyParser.scala

package com.linkingenius.parser

import java.io.File
import java.io.FileWriter

// Handler to perform write operations in a file
case class FileHandler(file: File) {

  def add(text: String): Unit = {
    val fw = new FileWriter(file, true)
    try { fw.write(text) }
    finally { fw.close }
  }

}

// Companion object for FileHandler
object FileHandler {
  implicit def file2FileHelper(file: File) = FileHandler(file)
}

import java.net.URL
import scala.io.Source
import scala.xml.XML.loadString
import scala.xml.Elem

// Inmutable class representing the currency info extracted from the XML file (ISO code and currency name)
case class CurrencyInfo(code: String, name: String)

// Finally, the currency parser, which performs the required operations to parse the remote XML file
object CurrencyParser {
  // Other source of info for currency codes: http://www.currency-iso.org/dl_iso_table_a1.xml
  val CurrencyCodeInfoURL = "http://www.tm-xml.org/TM-XML/TM-XML_xml/ISOCurrencyCode.xml"
  // User defined format for output
  val CurrencyOutput = "Currency code: %s - Currency name: %s\n"

  def main(args: Array[String]) {
    writeToFile(args(0), getCodesAndNamesFromCurrencies(loadString(getURLAsString(CurrencyCodeInfoURL))))
  }

  private def getURLAsString(url: String): String = Source.fromURL(new URL(url)).mkString

  private def getCodesAndNamesFromCurrencies(currencyInfoXML: Elem): Seq[CurrencyInfo] = {
    currencyInfoXML match {
      case <ISOCurrencyCode>{ currencies @ _* }</ISOCurrencyCode> =>
        for {
          currency @ <Currency>{ _* }</Currency> <- currencies
          code = (currency \ "CurrencyCode").text
          name = (currency \ "CurrencyName").text
        } yield CurrencyInfo(code, name)
      case _ => Seq()
    }
  }

  private def writeToFile(outputFileName: String, codesAndNames: Seq[CurrencyInfo]): Unit = {
    import FileHandler._
    val f = new File(outputFileName)
    f.delete
    codesAndNames map { ci => f.add(CurrencyOutput.format(ci.code, ci.name)) }
  }

}