问题
I'm looking at using a DoubleLinkedList. It's remove() method says "Removes the current node from the double linked list." but there are no other references to current in the page.
What is the current node, how do I set it, and surely this can't be the only way of removing an item?
回答1:
A DoubleLinkedList is at the same time the list itself and a list node, similar to the :: for a regular List. You can navigate from one cell to the next or to the previous one with next and prev, respectively, and get the value of a cell with elem.
scala> val list = collection.mutable.DoubleLinkedList(1,2,3,4,5)
list: scala.collection.mutable.DoubleLinkedList[Int] = DoubleLinkedList(1, 2, 3, 4, 5)
scala> list.next.next.remove() // list.next.next points on 3rd cell
scala> list
res0: scala.collection.mutable.DoubleLinkedList[Int] = DoubleLinkedList(1, 2, 4, 5)
Be careful if you remove the first cell, as you’ll need to reassign your var holding the list to the next cell:
scala> val list = collection.mutable.DoubleLinkedList(1,2,3,4,5)
list: scala.collection.mutable.DoubleLinkedList[Int] = DoubleLinkedList(1, 2, 3, 4, 5)
scala> list.remove() // remove first item
scala> list // this is now a 'dangling' cell, although it still points to the rest of the list
res6: scala.collection.mutable.DoubleLinkedList[Int] = DoubleLinkedList(1, 2, 3, 4, 5) // uh? didn't I remove the first cell?
scala> list.next.prev // we can check that it is not pointed back to by its next cell
res7: scala.collection.mutable.DoubleLinkedList[Int] = null
来源：https://stackoverflow.com/questions/7764694/what-is-the-current-element-in-a-scala-doublelinkedlist