Black monkey house: Scala classes inherit

Like Java extends keyword, given subclass definition needs no fields and methods of the superclass, or superclass rewritten.

1、extends

class Father {
  def shout(msg: String): Unit ={
    println("Father中的shout方法调用" + msg)
  }
}

//使用extends 关键字 继承 父类
//父类 非抽象的 需要用 override关键字
class Child extends Father{
  override def shout(msg: String): Unit = {
    println("Child中的shout方法调用" + msg)
  }
}

object ChildMain {
  def main(args: Array[String]): Unit = {
    val father = new Father
    val child = new Child

    father.shout("hahaha")
    child.shout("xixixi")
  }
}

尖叫提示：如果类声明为final，他将不能被继承。如果单个方法声明为final，将不能被重写

2, plus inherited trait mixed

class AFather {

}

trait Adminal{
  var leg:Int = _
}

trait Victor{
  val bo:Int
}

//一个类只能继承一个父类，可以混入多个特质
//当不继承父类，但需要混入特质的时候，第一个关键字，使用extends，后跟with关键字
class Dog extends AFather with Adminal with Victor{
  override val bo: Int = 6
}

3, not inherited, only mixed character, still use the extends keyword

class AFather {

}

trait Adminal{
  var leg:Int = _
}

trait Victor{
  val bo:Int
}

//一个类只能继承一个父类，可以混入多个特质
//当不继承父类，但需要混入特质的时候，第一个关键字，使用extends，后跟with关键字
class Dog extends Adminal with Victor{
  override val bo: Int = 6
}

Reproduced in: https: //www.jianshu.com/p/edb46628b37b