坐标

object da4 {

    class Point(var x: Double, var y: Double) {
      // 方法1：判断象限
      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 {
          "在坐标轴上"
        }
      }

      // 方法2：到原点的距离
      def getDist(): Double = Math.sqrt(x * x + y * y)

      // 方法3：到另一个点的距离
      def fromPoint(other: Point): Double = {
        val dx = x - other.x
        val dy = y - other.y
        Math.sqrt(dx * dx + dy * dy)
      }

      // 方法4：重写 equals 判断是否为同一点
      override def equals(other: Any): Boolean = {
        val o = other.asInstanceOf[Point]
        o.x==x && o.y==y
      }

      def canEqual(other: Any): Boolean = other.isInstanceOf[Point]

      // 方法5：重写 toString 友好输出信息
      override def toString: String = s"${x},${y}"
    }
    class LabelPoint(val color: String, x: Double, y: Double) extends Point(x, y) {
      override def toString: String = s"${color}: ${x}, ${y}"
      println(s"LabelPoint构造器  ${color}")
    }

    def main(args: Array[String]): Unit = {
      val s1 =new Point(3.0,4.0)
      val s2 = new Point(6.0,8.0)
      println(s1.whereAmI())
      println(s1.getDist())
      println(s1.fromPoint(s2))
      println(s1==s2)
      println(s1.toString)
      val s3 =new LabelPoint("black",1.0,0)
      val s4 =new LabelPoint("black",2.0,0)
      println(s3.whereAmI())
      println(s3.getDist())
      println(s3.fromPoint(s4))
      println(s3==s4)
      println(s3.toString)
    }


}