Scala StringInputStream: have a String and read from it with an InputStream

StringInputStream.scala

import java.io.InputStream

class StringInputStream(s: String) extends InputStream {
  private val bytes = s.getBytes

  private var pos = 0

  override def read(): Int = if (pos >= bytes.length) {
    -1
  } else {
    val r = bytes(pos)
    pos += 1
    r.toInt
  }
}