代碼:
import scala.collection.immutable.Queue
val q = new Queue[Int]
錯誤提示:
constructor Queue in class Queue cannot be accessed in object caseClass Access to protected constructor Queue not permitted because enclosing object caseClass in package practice is not a subclass of class Queue in package immutable where target is defined
這是聲明類未繼承Queue,所以可以看出它的構造函數式protected的,因此你不能使用new訪問它的構造函數.
不過你可以使用它的伴生對象來生成一個Queue的實例:
val q= Queue[Int]()