将集合项复制到 .NET 中的另一个集合
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原文地址: http://stackoverflow.com/questions/147416/
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Copy collection items to another collection in .NET
提问by Matt Hanson
In .NET (VB), how can I take all of the items in one collection, and add them to a second collection (without losing pre-existing items in the second collection)? I'm looking for something a little more efficient than this:
在 .NET (VB) 中，如何获取一个集合中的所有项目，并将它们添加到第二个集合（而不会丢失第二个集合中预先存在的项目）？我正在寻找比这更有效的东西：
For Each item As Host In hostCollection1
hostCollection2.Add(item)
Next
My collections are generic collections, inherited from the base class -- Collection(Of )
我的集合是泛型集合，继承自基类 -- Collection(Of )
回答by jop
You can use AddRange: hostCollection2.AddRange(hostCollection1).
您可以使用 AddRange: hostCollection2.AddRange(hostCollection1)。
回答by Ben Hoffstein
I know you're asking for VB, but in C# you can just use the constructor of the collection to initialize it with any IEnumerable. For example:
我知道您要求使用 VB，但在 C# 中，您可以使用集合的构造函数来使用任何 IEnumerable 对其进行初始化。例如：
List<string> list1 = new List<string>();
list1.Add("Hello");
List<string> list2 = new List<string>(list1);
Perhaps the same kind of thing exists in VB.
也许在VB中也存在同样的事情。
回答by johnc
I always use the List<T>.AddRange(otherList<T>)function. Again, if this is a list of objects, they will be references the same thing.
我总是使用该List<T>.AddRange(otherList<T>)功能。同样，如果这是一个对象列表，它们将引用相同的东西。
You have not specified what sort of collection though, AddRange doesn't exist in CollectionBase inherited objects
您尚未指定哪种集合，但 CollectionBase 继承对象中不存在 AddRange
回答by David Robbins
Don't forget that you will be getting a reference and not a copy if you initialize your List2 to List1. You will still have one set of strings unless you do a deep clone.
不要忘记，如果您将 List2 初始化为 List1，您将获得引用而不是副本。除非您进行深度克隆，否则您仍将拥有一组字符串。
回答by Kangkan
This is available when one use an IList. But AddRangemethod is not available in Collection. I thought of casting Collectionto List, but it is not possible.
当使用IList. 但是AddRange方法在Collection. 我想投射Collection到List，但这是不可能的。
回答by Austin Salonen
Ben's solution does exist for VB.Net:
Ben 的解决方案确实存在于 VB.Net：
Dim collection As IEnumerable(Of T)
Dim instance As New List(collection)
Here is the linked documentation.
这是链接的文档。
However, one thing I would be concerned with is whether or not it does a shallow copy or a deep copy.
但是，我会关心的一件事是它是否执行浅拷贝或深拷贝。
回答by Cory Foy
Unless you want both collections to modify the same set of objects, then each object is going to have to be copied to the Heap. Maybe you can describe your scenario of how this is impacting your performance and we can find a good solution.
除非您希望两个集合都修改同一组对象，否则每个对象都必须复制到堆中。也许您可以描述一下这如何影响您的性能的场景，我们可以找到一个很好的解决方案。
回答by Cory Foy
Array.Copymay solve your problem.
Array.Copy可能会解决您的问题。
回答by Aaron Powell
回答by user4951
Not sure for this one
不确定这个
Why not just do this
为什么不这样做
Dim newlines = _singSongs.ToList
That .tolist means it creates a whole new list
.tolist 意味着它创建了一个全新的列表
