How do I clone a generic list in C#?

Question

I have a generic list of objects in C#, and wish to clone the list. The items within the list are cloneable, but there doesn't seem to be an option to do list.Clone().

Is there an easy way around this?

Answer 1

To clone a list just call .ToList()

Microsoft (R) Roslyn C# Compiler version 2.3.2.62116
Loading context from 'CSharpInteractive.rsp'.
Type "#help" for more information.
> var x = new List<int>() { 3, 4 };
> var y = x.ToList();
> x.Add(5)
> x
List<int>(3) { 3, 4, 5 }
> y
List<int>(2) { 3, 4 }
> 

Answer 2

If you have already referenced Newtonsoft.Json in your project and your objects are serializeable you could always use:

List<T> newList = JsonConvert.DeserializeObject<T>(JsonConvert.SerializeObject(listToCopy))

Possibly not the most efficient way to do it, but unless you're doing it 100s of 1000s of times you may not even notice the speed difference.

Answer 3

I use automapper to copy an object. I just setup a mapping that maps one object to itself. You can wrap this operation any way you like.

http://automapper.codeplex.com/

Answer 4

public static object DeepClone(object obj) 
{
  object objResult = null;
  using (MemoryStream  ms = new MemoryStream())
  {
    BinaryFormatter  bf =   new BinaryFormatter();
    bf.Serialize(ms, obj);

    ms.Position = 0;
    objResult = bf.Deserialize(ms);
  }
  return objResult;
}

This is one way to do it with C# and .NET 2.0. Your object requires to be [Serializable()]. The goal is to lose all references and build new ones.

Answer 5

I've made for my own some extension which converts ICollection of items that not implement IClonable

static class CollectionExtensions
{
    public static ICollection<T> Clone<T>(this ICollection<T> listToClone)
    {
        var array = new T[listToClone.Count];
        listToClone.CopyTo(array,0);
        return array.ToList();
    }
}

Answer 6

    public List<TEntity> Clone<TEntity>(List<TEntity> o1List) where TEntity : class , new()
    {
        List<TEntity> retList = new List<TEntity>();
        try
        {
            Type sourceType = typeof(TEntity);
            foreach(var o1 in o1List)
            {
                TEntity o2 = new TEntity();
                foreach (PropertyInfo propInfo in (sourceType.GetProperties()))
                {
                    var val = propInfo.GetValue(o1, null);
                    propInfo.SetValue(o2, val);
                }
                retList.Add(o2);
            }
            return retList;
        }
        catch
        {
            return retList;
        }
    }