Point.scala

class Point {
  var x : Int = 0
  var y : Int = 0

  def apply(newX : Int, newY : Int) : Point = {
    x = newX
    y = newY
    this
  }

  def +(operand : Point) : Point = {
    Point(x + operand.x, y + operand.y)
  }

  def -(operand : Point) : Point = {
    Point(x - operand.x, y - operand.y)
  }

  def Δ(operand : Point) : Point = {
    this delta operand
  }

  def delta(operand : Point) : Point = {
    val mx = Math.max(x - operand.x, operand.x - x)
    val my = Math.max(y - operand.y, operand.y - y)
    Point(mx, my)
  }

  def >=<(operand : Point) : Point = {
    this midpoint operand
  }

  def midpoint(operand : Point) : Point = {
    val mx = (x + operand.x) / 2
    val my = (y + operand.y) / 2
    Point(mx, my)
  }

  override def toString() : String = {
    "[%,d, %,d]".format(x,y)
  }

  override def equals(obj : Any) : Boolean = {
    if (obj.isInstanceOf[Point]) {
      val ob = obj.asInstanceOf[Point]
      ob.x == this.x && ob.y == this.y
    } else {
      false
    }
  }

  override def hashCode() : Int = {
    x * 5 + y * 3
  }
}

// Static methods, instead of saying new Point(x, y) just Point(x, y)
object Point {
  def apply(x : Int, y : Int) : Point = {
    val p = new Point
    p(x, y)
  }
}

object Driver {
  def main(args : Array[String]) = {
    val p1 = Point(5, 3)
    println(p1)

    val p2 = Point(1, 1)
    println(p2)

    printf("%s Δ %s = %s%n", p1, p2, p1 Δ p2)
    printf("%s and %s have a midpoint of %s%n", p1, p2, p1 >=< p2)
    printf("%s == %s => %b%n", p1, p2, p1 == p2)
    printf("%s Δ %s == %s Δ %s => %b%n", p1, p2, p2, p1, (p2 Δ p1) == (p1 Δ p2))
  }
}

/*
OUTPUT:
[5, 3]
[1, 1]
[5, 3] Δ [1, 1] = [4, 2]
[5, 3] and [1, 1] have a midpoint of [3, 2]
[5, 3] == [1, 1] => false
[5, 3] Δ [1, 1] == [1, 1] Δ [5, 3] => true
*/