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

I usually use this little collection of extension methods:

public static class EnumerableExtension
{
    public static T PickRandom(this IEnumerable source)
    {
        return source.PickRandom(1).Single();
    }

    public static IEnumerable PickRandom(this IEnumerable source, int count)
    {
        return source.Shuffle().Take(count);
    }

    public static IEnumerable Shuffle(this IEnumerable source)
    {
        return source.OrderBy(x => Guid.NewGuid());
    }
}

For a strongly typed list, this would allow you to write:

var strings = new List();
var randomString = strings.PickRandom();

If all you have is an ArrayList, you can cast it:

var strings = myArrayList.Cast();