例题

package level02

object renwu2 {
    class Point(var x: Double, var y: Double) {
      def whereAmI(): String = {
        if (x > 0 && y > 0) "第1象限"
        else if (x < 0 && y > 0) "第2象限"
        else if (x < 0 && y < 0) "第3象限"
        else if (x > 0 && y < 0) "第4象限"
        else "未知"
      }

      def getDist(): Double = {
        Math.sqrt(x * x + y * y)
      }

      def fromPoint(other: Point): Double = {
        val dx = other.x - this.x
        val dy = other.y - this.y
        Math.sqrt(dx * dx + dy * dy)
      }



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

          val other = obj.asInstanceOf[Point]
          this.x == other.x && this.y == other.y
        }

        override def toString: String = {
          s"Point(${x}, ${y})"
        }
      }


    class LabelPoint(label: String, x: Double, y: Double) extends Point(x, y) {
      override def toString: String = s"LabelPoint(标签: $label, 坐标: ($x, $y))"
    }

  def main(args: Array[String]): Unit = {
    val p1 = new Point(1.0,1.0)
    val p2 = new Point(1.0,1.0)
    val p3 = new LabelPoint("black", 1, 2)
    println(p1 == p2)
    println(p1.whereAmI())
    println(p1.getDist())
    println(p1.fromPoint(p2))
    println(p3)
    }
}