学习scala trait

// 类接口，但是可以实现方法
// 作用 多重继承
trait traitA{
  val tnum: Int
  def log(msg: String): Unit ={
    println("log : " + msg)
  }
}

trait traitB extends traitA{
  def test: Unit ={
    log("trait tb call ")
  }
}

trait traitC extends traitB{
  override def test: Unit ={
    log("trait tc call ")
  }
}

// class
abstract  class ClassA {
  def abstractMethod
}

class classB extends ClassA{
   def abstractMethod: Unit ={
    println("ClassB is call")
  }
}

// 测试多重继承
class classC extends classB with traitB{
  val tnum:Int = 3
  def calltrait(): Unit ={
    test
  }

  def callabstract(): Unit ={
    abstractMethod
  }
}

object Testtrait extends  App{
  var c1 = new classC
  c1.calltrait()
  c1.callabstract()

  var c = new classC with traitC
  c.calltrait()
  c.callabstract()
  println(c.tnum)
}