案例作业

package level02

object Class016 {
  class Point(var x: Double, var y: Double) {
    def whereAmI(): String = {
      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 if (x > 0 && y < 0) "第四象限"
      else if (x == 0 && y == 0) "原点"
      else if (x == 0) "y轴上"
      else "x轴上"
    }

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

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

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

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

  // 作业：发稀土掘金
  class LabelPoint(label: String, x: Double, y: Double) extends Point(x, y) {
    override def toString: String = s"LabelPoint($label, $x, $y)"
  }

  def main(args: Array[String]): Unit = {
    // 测试
    val p1 = new Point(1.0, 1.0)
    val p2 = new Point(1.0, 1.0)
    println(p1.whereAmI())
    println(p1.getDist())
    println(p1.fromPoint(p2))
    println(p1 == p2)

    val lp = new LabelPoint("black", 1, 2)
    println(lp)
    println(lp.whereAmI())
    println(lp.getDist())
  }
}

运行结果：