How to sort an iList (With linq or without)

Question

Possible Duplicate:
Sorting an IList in C#

I have the following method and I need to sort the iList object that is being passed to it (inside this method). I have tried linq but since it's an interface I'm getting errors.

Thanks in advance

private void AddListToTree(ComponentArt.Web.UI.TreeView treeView, IList list)
{
//NEED TO SORT THE LIST HERE
}

Please note that my type is Dynamic.

I think I should create a temporary collection, populate if from my instance of IList, sort it, get appropriate instance of the object supporting IList and use it instead of my non-sorted instance of IList which I should leave intact. So I tried getting the type like following:

Type[] listTypes = list.GetType().GetGenericArguments();
Type listType = null;
if (listTypes.Length > 0)
{
listType = listTypes[0];
}

But I cannot create a new List with this type

Answer 1

You should use the generic form of IList to be able to use the LINQ extension methods:

private void AddListToTree<T>(ComponentArt.Web.UI.TreeView treeView,
                              IList<T> list)
{
    var orderedList = list.OrderBy(t => t);
    // ...
}

If you can't modify the method's signature but you know the type of the objects in the IList, you can use Cast:

private void AddListToTree(ComponentArt.Web.UI.TreeView treeView,
                           IList list)
{
    var orderedList = list.Cast<SomeType>().OrderBy(x => x);
    // ...
}

Answer 2

You could use Cast<T>() to change it to IList<T> then use OrderBy():

private void AddListToTree<T>(ComponentArt.Web.UI.TreeView treeView, IList list)
{
    var ordered = list.Cast<T>().OrderBy(e => e);
}

Somewhere you will need to know the type to do the sorting.

Answer 3

For LINQ: Duplicate question as : Sorting an IList in C#

You can also use extension methods to add the Sort command to IList: Why is there no Sort for IList<T>?!?! (edited)'

You can do the following (WhicH I don't endorse, but it's still doable)

IList list;
ArrayList al = new ArrayList(list);
al.Sort();

You can also utilize IComparable: http://devpinoy.org/blogs/keithrull/archive/2007/03/23/sorting-a-generic-list-of-object-in-c-using-icomparable-and-anonymous-delegates.aspx

or

http://foxsys.blogspot.com/2007/06/how-to-sort-generic-ilist.html

Answer 4

One way (note that you must specify the item type in the from clause):

IList list = new ArrayList();
list.Add("z");
list.Add("a");
list.Add("c");

IEnumerable<string> ordered =
    from string item in list
    orderby item
    select item;

foreach (var s in ordered)
{
    Console.WriteLine(s);
}

Prints:

a
c
z

Note: Based on your later comment of

they can be type of 3 different classes

this will not work. I would seriously consider refactoring the calling code.

If you have no ability to edit the types, and if the types should not be intermixed in the sorted list, here's an option:

var one = list.OfType<TypeOne>().OrderBy(x => x.Id);
var two = list.OfType<TypeTwo>().OrderBy(x => x.Name);
var three = list.OfType<TypeThree>().OrderBy(x => x.Nom);

var result =
    one.Cast<object>()
    .Concat(two.Cast<object>())
    .Concat(three.Cast<object>());

Answer 5

One option is to create an ArrayList adapter around the IList using ArrayList.Adapter, then sort it using ArrayList.Sort. This is if you need an in-place sorting operation that mutates the array contents, rather than returning a sorted enumeration.

Answer 6

If you can't change the signature or use LINQ, use an extension method or custom method.

Examples given in the duplicate question listed by @Ryan Ternier:

LINQ: Duplicate question as : Sorting an IList in C#