[Scala] hashCode and equals of mutable object

HashCodeEqualsExample.scala

import scala.collection.immutable.HashMap
/**
 * hashCode and equals of mutable object (not working well because of object mutability)
 * the only way to make it working is to use immutable object
 */
class Point2(var x: Int, var y: Int) {
  def move(mx: Int, my: Int): Unit = {
    x = x + mx
    y = y + my
  }

  override def hashCode(): Int = y + (31 * x)

  def canEqual(that: Any): Boolean = that match {
    case p: Point2 => true
    case _ => false
  }

  override def equals(that: Any): Boolean = {

    def strictEquals(other: Point2) = this.x == other.x && this.y == other.y

    that match {
      case a: AnyRef if this eq a => true
      case p: Point2 => (p canEqual this) && strictEquals(p)
      case _ => false
    }
  }
}

object Main {
  def main(args: Array[String]) {
    val x = new Point2(1, 1) 
    val y = new Point2(1, 2) 
    val z = new Point2(1, 1) 
    val map = HashMap(x -> "OKI", y -> "DOKI") 
    println(map(x)) 
    println(map(z)) 
    println(x.##) 
    println(z.##) 
    x.move(1, 1)
    map(y) //> res4: String = DOKI
    //map(x) //will throw an exception
    //map(z) //will throw an exception
    println(map.find(_._1 == x)) //object x will be found!!!! It's because Point2 is mutable and its
      						 //hashCode changes during x object life cycle (after calling move())
  }
}