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Scala DoubleLinkedList 中的当前元素是什么？

发布于 2024-12-09 16:34:44 字数 315 浏览 0 评论 0原文

我正在查看使用 DoubleLinkedList。它的remove()方法表示“从双链表中删除当前节点。”但是页面中没有其他对当前节点的引用。

当前节点是什么，如何设置它，并且这肯定不是删除项目的唯一方法？

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七度光 2024-12-16 16:34:44

DoubleLinkedList 同时是列表本身和一个列表节点，类似于常规List的::代码>.您可以分别使用 next 和 prev 从一个单元格导航到下一个或上一个单元格，并使用 elem 获取单元格的值>。

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)

如果删除第一个单元格，请小心，因为您需要将保存列表的 var 重新分配给下一个单元格：

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

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

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