学习scala笔记--9 scala 继承 extends

 

 

 

 

scala 继承 extends   

 覆盖使用  override

 调用父类  super

 

 

 

 

scala> :paste

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

 

 

class Person

{

var name="tom"

def getName= name

}

 

 

class Student extends Person {

 var score = 0

 def getScore = score

 override def getName = "-----"+ super.getName

}

 

// Exiting paste mode, now interpreting.

 

defined class Person

defined class Student

 

 

scala> val s = new Student()

s: Student = Student@69cd1085

 

scala> s.getName

res0: String = -----tom

 

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isInstanceOf  and    asInstanceOf

 

scala> class Person

defined class Person

 

scala> class Student extends Person

defined class Student

 

scala> val p : Person = new Student()

p: Person = Student@29c1249a

 

scala> var s:Student = null

s: Student = null

 

scala> if( p.isInstanceOf[Student])  s= p.asInstanceOf[Student]

 

scala> s

res3: Student = Student@29c1249a

 

 

 

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scala> class Person

defined class Person

 

scala> class Student extends Person

defined class Student

 

scala> val p2:Person = new Student()

p2: Person = Student@3b32f0b4

 

scala> val p2:Person = new Student()

p2: Person = Student@3b32f0b4

 

scala> p2.isInstanceOf[Student]

res6: Boolean = true

 

scala> p2.getClass == classOf[Student]

res7: Boolean = true

 

--------- 注意这里的  false  ---------  注意这里和  isInstanceOf 的区别

scala> p2.getClass == classOf[Person]

res8: Boolean = false

 

scala> p2.isInstanceOf[Person]

res9: Boolean = true

 

 

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使用模式匹配进行类型判断

 

 

 

scala>  p2 match {

     | case per: Person => println("is person ")

     | case _ =>println("other class ") }

is person 

 

 

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