lock.scala

val s = Array("A", "B", "C")
val lock = new java.util.concurrent.locks.ReentrantLock()
val total = s.length
var token: Int = 0
val cvs = s.map(i => lock.newCondition())

val threads = for (t <- 0 until 3) yield {
  val thread = new Thread {
    override def run {
      lock.lock()
      for (i <- 0 until 10) {
        while (token != t) cvs(t).await()
        println(s(t))
        token = (token + 1) % total
        cvs(token).signal()
      }
      lock.unlock()
    }
  }
  thread.start()
  thread
}

for (thread <- threads) thread.join()