Scala HashCode builder

gistfile1.java

  val SEED = 23

  def hash(seed: Int, value: Boolean): Int = firstTerm(seed) + (if (value) 1 else 0)
  def hash(seed: Int, value: Char): Int = firstTerm(seed) + value.asInstanceOf[Int]
  def hash(seed: Int, value: Int): Int = firstTerm(seed) + value
  def hash(seed: Int, value: Long): Int = firstTerm(seed)  + (value ^ (value >>> 32) ).asInstanceOf[Int]
  def hash(seed: Int, value: Float): Int = hash(seed, JFloat.floatToIntBits(value))
  def hash(seed: Int, value: Double): Int = hash(seed, JDouble.doubleToLongBits(value))
  def hash(seed: Int, anyRef: AnyRef): Int = {
    var result = seed
    if (anyRef == null) result = hash(result, 0)
    else if (!isArray(anyRef)) result = hash(result, anyRef.hashCode())
    else { // is an array
      for (id <- 0 until JArray.getLength(anyRef)) {
        val item = JArray.get(anyRef, id)
        result = hash(result, item)
      }
    }
    result
  }
  private def firstTerm(seed: Int): Int = PRIME * seed
  private def isArray(anyRef: AnyRef): Boolean = anyRef.getClass.isArray
  private val PRIME = 37