How to access random item in list?

Question

I have an ArrayList, and I need to be able to click a button and then randomly pick out a string from that list and display it in a messagebox.

How would I go about

Answer 1

Or simple extension class like this:

public static class CollectionExtension
{
    private static Random rng = new Random();

    public static T RandomElement(this IList list)
    {
        return list[rng.Next(list.Count)];
    }

    public static T RandomElement(this T[] array)
    {
        return array[rng.Next(array.Length)];
    }
}

Then just call:

myList.RandomElement();

Works for arrays as well.

I would avoid calling OrderBy() as it can be expensive for larger collections. Use indexed collections like List or arrays for this purpose.