什么时候我应该使用List vs LinkedList

什么时候使用List和LinkedList更好?

当前回答

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请阅读对这个答案的评论。人们说我没有适当的测试。我同意这不应该是一个可以接受的答案。就像我一样我做了一些测试，想和大家分享。

最初的回答…

我发现了有趣的结果:

// Temporary class to show the example
class Temp
{
    public decimal A, B, C, D;

    public Temp(decimal a, decimal b, decimal c, decimal d)
    {
        A = a;            B = b;            C = c;            D = d;
    }
}

链表(3.9秒)

        LinkedList<Temp> list = new LinkedList<Temp>();

        for (var i = 0; i < 12345678; i++)
        {
            var a = new Temp(i, i, i, i);
            list.AddLast(a);
        }

        decimal sum = 0;
        foreach (var item in list)
            sum += item.A;

列表(2.4秒)

        List<Temp> list = new List<Temp>(); // 2.4 seconds

        for (var i = 0; i < 12345678; i++)
        {
            var a = new Temp(i, i, i, i);
            list.Add(a);
        }

        decimal sum = 0;
        foreach (var item in list)
            sum += item.A;

即使你只是访问数据，本质上也要慢得多!!我说永远不要使用linkedList。

下面是另一个执行大量插入的比较(我们计划在列表中间插入一个项)

链表(51秒)

        LinkedList<Temp> list = new LinkedList<Temp>();

        for (var i = 0; i < 123456; i++)
        {
            var a = new Temp(i, i, i, i);

            list.AddLast(a);
            var curNode = list.First;

            for (var k = 0; k < i/2; k++) // In order to insert a node at the middle of the list we need to find it
                curNode = curNode.Next;

            list.AddAfter(curNode, a); // Insert it after
        }

        decimal sum = 0;
        foreach (var item in list)
            sum += item.A;

榜单(7.26秒)

        List<Temp> list = new List<Temp>();

        for (var i = 0; i < 123456; i++)
        {
            var a = new Temp(i, i, i, i);

            list.Insert(i / 2, a);
        }

        decimal sum = 0;
        foreach (var item in list)
            sum += item.A;

有插入位置引用的链表(。04秒)

        list.AddLast(new Temp(1,1,1,1));
        var referenceNode = list.First;

        for (var i = 0; i < 123456; i++)
        {
            var a = new Temp(i, i, i, i);

            list.AddLast(a);
            list.AddBefore(referenceNode, a);
        }

        decimal sum = 0;
        foreach (var item in list)
            sum += item.A;

因此，只有当你计划插入几个项目，并且你也在某个地方有你计划插入项目的引用时，才使用链表。只是因为你必须插入很多项，这并不会使它更快，因为搜索你想要插入的位置需要时间。

2012-09-17 20:47:37

其他回答

链表相对于数组的主要优点是，链接为我们提供了有效地重新排列项的能力。塞奇威克，第91页

2012-11-25 08:52:14

List和LinkedList之间的区别在于它们的底层实现。List是基于数组的集合(ArrayList)。LinkedList是基于节点指针的集合(LinkedListNode)。在API级别的使用上，它们几乎是相同的，因为它们都实现了相同的接口集，如ICollection、IEnumerable等。

关键的区别在于性能问题。例如，如果您正在实现具有大量“INSERT”操作的列表，LinkedList的性能优于list。因为LinkedList可以在O(1)时间内完成，但是List可能需要扩展底层数组的大小。要了解更多信息/细节，你可能想要阅读LinkedList和数组数据结构之间的算法差异。http://en.wikipedia.org/wiki/Linked_list和Array

希望这能有所帮助，

2008-10-04 08:35:55

链表提供了快速插入或删除列表成员的功能。链表中的每个成员都包含指向链表中下一个成员的指针，因此要在位置i插入一个成员:

更新成员i-1中的指针，使其指向新成员将新成员中的指针设置为指向成员I

链表的缺点是不能进行随机访问。访问成员需要遍历列表，直到找到所需的成员。

2008-10-04 08:34:23

我之前的回答不够准确。 D是正确答案但现在我可以发布更有用和正确的答案。

我做了一些额外的检查您可以通过以下链接找到它的源代码，并在您自己的环境中通过https://github.com/ukushu/DataStructuresTestsAndOther.git重新检查它

短的结果:

Array need to use: So often as possible. It's fast and takes smallest RAM range for same amount information. If you know exact count of cells needed If data saved in array < 85000 b (85000/32 = 2656 elements for integer data) If needed high Random Access speed List need to use: If needed to add cells to the end of list (often) If needed to add cells in the beginning/middle of the list (NOT OFTEN) If data saved in array < 85000 b (85000/32 = 2656 elements for integer data) If needed high Random Access speed LinkedList need to use: If needed to add cells in the beginning/middle/end of the list (often) If needed only sequential access (forward/backward) If you need to save LARGE items, but items count is low. Better do not use for large amount of items, as it's use additional memory for links.

更多的细节:

有趣的是:

LinkedList<T> internally is not a List in .NET. It's even does not implement IList<T>. And that's why there are absent indexes and methods related to indexes. LinkedList<T> is node-pointer based collection. In .NET it's in doubly linked implementation. This means that prior/next elements have link to current element. And data is fragmented -- different list objects can be located in different places of RAM. Also there will be more memory used for LinkedList<T> than for List<T> or Array. List<T> in .Net is Java's alternative of ArrayList<T>. This means that this is array wrapper. So it's allocated in memory as one contiguous block of data. If allocated data size exceeds 85000 bytes, it will be moved to Large Object Heap. Depending on the size, this can lead to heap fragmentation(a mild form of memory leak). But in the same time if size < 85000 bytes -- this provides a very compact and fast-access representation in memory. Single contiguous block is preferred for random access performance and memory consumption but for collections that need to change size regularly a structure such as an Array generally need to be copied to a new location whereas a linked list only needs to manage the memory for the newly inserted/deleted nodes.

2015-03-25 18:41:44