父类与子类

//  父类： name, age
  class Animal(val name:String, var age: Int) {
  println(s"父类构造器 ......${name} ${age}")

    def eat():Unit = {
      println(s"${name} ${age} eating.....")
    }
}

// 子类: name,age, color
class Dog(name:String, age:Int, var color:String) extends Animal(name,age) {
  println(s"子类构造器 .....${name} ${age} ${color}")
}


def main(args: Array[String]):Unit = {
  val dog1 = new Dog("旺财", 1, "黑色")
  dog1.eat()

作业

class Point(var x: Double, var y: Double) {
  // 方法1：判断所在象限
  def whereAmI(): String = {
    (x, y) match {
      case (0.0, 0.0) => "原点"
      case (0.0, _) => "y轴上"
      case (_, 0.0) => "x轴上"
      case (x, y) if x > 0 && y > 0 => "第一象限"
      case (x, y) if x < 0 && y > 0 => "第二象限"
      case (x, y) if x < 0 && y < 0 => "第三象限"
      case (x, y) if x > 0 && y < 0 => "第四象限"
    }
  }

  // 方法2：计算到原点的距离
  def getDist(): Double = {
    math.sqrt(x * x + y * y)
  }

  // 方法3：计算与另一个点的距离
  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判断是否为同一个点
  override def equals(other: Any): Boolean = {
    other match {
      case that: Point => this.x == that.x && this.y == that.y
      case _ => false
    }
  }

  // 方法5：重写toString输出友好信息
  override def toString: String = s"Point(x=$x, y=$y)"

子类

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