学习scala笔记--26 类型参数--下边界

 

 

 

 

 下边界

 

 

 scala> class Father(val name:String)

defined class Father

 

scala> class Child(name:String) extends Father(name)

defined class Child

 

 

 scala> :paste

// Entering paste mode (ctrl-D to finish)

 

def getIdCard[R >: Child](p :R){

    println(p.getClass)

     if(p.getClass == classOf[Child])  println("please tell us your father's name")

    else if(p.getClass == classOf[Father]) println("pleanse tell us your child's name")

    else  println("sorry  you can't get this Idcard")

}

 

// Exiting paste mode, now interpreting.

 

getIdCard: [R >: Child](p: R)Unit

 

scala> 

 

scala>  val f = new Father("fa")

f: Father = Father@5ec88f9e

 

scala>  val c = new Child("ch")

c: Child = Child@b5d9f1e

 

scala> getIdCard(f)

class $line3.$read$$iw$$iw$Father

pleanse tell us your child's name

 

scala>  getIdCard(c)

class $line4.$read$$iw$$iw$Child

please tell us your father's name

 

scala>  getIdCard("dd")

class java.lang.String

sorry  you can't get this Idcard