How can I copy an IList to an IList of the same type?

Question

In C#, if I have an IList , and I do not know the type of the objects in the IList , how can I create a copy of the IList ?

Here is the situation:

I have a CollectionEditor that can modify items in an IList . If the cancel button is pressed, I need to restore the IList before the items were changed.

Answer 1

There are two different problems here. Copying a list to another list is relatively easy - if you don't need the second list to be the exact same type of concrete list you could use ToList() , otherwise you could just Add in a loop. However, that won't solve your problem unless the T here is something immutable. It would be fine for string , int etc, but copying the references to a complex type won't allow you to restore the list, as individual items could have been edited in the UI. To solve that problem you need a "deep copy" (or there are some other strategies, but that is the simplest). And as has been noted: one way to do a deep copy is: serialization. By taking a snapshot of the data in XML, json, or some other serialization format, "restore" can be implemented via "deserialize".

Of course, if your T has a deep-clone method built in, you might be able to use that instead of serialization. It is ambiguous whether ICloneable is deep vs shallow, so I don't think it is sufficient to insist where T : ICloneable .

Answer 2

ToList创建一个副本：

IList x = y.ToList();