象限

package level2

object Sc74 {

  class Point(var x: Double, var y: Double) {
    // 计算所在象限
    def whereAmI(): String = {
      if (x == 0 && y == 0) "原点"
      else if (x > 0 && y > 0) "第一象限"
      else if (x < 0 && y > 0) "第二象限"
      else if (x < 0 && y < 0) "第三象限"
      else "第四象限"
    }

    // 到原点的距离
    def getDist(): Double = Math.sqrt(x * x + y * y)

    // 到另一点的距离
    def fromPoint(other: Point): Double = {
      val dx = x - other.x
      val dy = y - other.y
      Math.sqrt(dx * dx + dy * dy)
    }

    // 重写equals方法
    override def equals(obj: Any): Boolean = obj match {
      case that: Point => this.x == that.x && this.y == that.y
      case _ => false
    }

    // 重写toString方法
    override def toString: String = s"($x, $y)"
  }

  // 子类LabelPoint
  class LabelPoint(val label: String, x: Double, y: Double) extends Point(x, y)

  def main(ars: Array[String]): Unit = {
    // 测试Point
    val p1 = new Point(3, 4)
    println(s"p1坐标: $p1")
    println(s"p1所在象限: ${p1.whereAmI()}")
    println(s"p1到原点距离: ${p1.getDist()}")

    val p2 = new Point(-1, -1)
    println(s"p1到p2距离: ${p1.fromPoint(p2)}")

    // 测试LabelPoint
    val lp = new LabelPoint("起点", 0, 0)
    println(s"标签点: ${lp.label}, 坐标: $lp, 位置: ${lp.whereAmI()}") // 输出：√13 ≈ 3.6055...
  }
}