Covariance and the scala

package Scaladay02kcomkawr

** // Covariance and /

**
is the generic definition *** java left and right sides of generics to be consistent

• For example polymorphism in two ways to look at is not allowed

• List list = new ArrayList();

• List list2 = new ArrayList();

• Under scala in default it is not allowed but is very flexible scala

• Thus adding the definition of the generic symbol [+ T] covariant [-T] The inverter is the case of two or more can be achieved

• Covariant superclass refers to the right-hand side when the left generic

• Inverter means is a left side of the equal sign on the right side is a subclass of the generic generic

• Multi set for operation to do **
  / *
  Object CovarianceInversion {
  DEF main (args: the Array [String]): Unit = {
  Val List: the Test [Object] = new new the Test Person

  val list1:Test01[person]=new Test01Object

}
}
// define covariant
class Test [+ T] {

}
// define inverter
class Test01 [-T] {

}

class person {
“类”
}