Shortcut for creating single item list in C#

Simply use this:

List<string> list = new List<string>() { "single value" };

You can even omit the () braces:

List<string> list = new List<string> { "single value" };

Update: of course this also works for more than one entry:

List<string> list = new List<string> { "value1", "value2", ... };

var list = new List<string>(1) { "hello" };

Very similar to what others have posted, except that it makes sure to only allocate space for the single item initially.

Of course, if you know you'll be adding a bunch of stuff later it may not be a good idea, but still worth mentioning once.

Michael's idea of using extension methods leads to something even simpler:

public static List<T> InList<T>(this T item)
{
    return new List<T> { item };
}

So you could do this:

List<string> foo = "Hello".InList();

I'm not sure whether I like it or not, mind you...

A different answer to my earlier one, based on exposure to the Google Java Collections:

public static class Lists
{
    public static List<T> Of<T>(T item)
    {
        return new List<T> { item };
    }
}

Then:

List<string> x = Lists.Of("Hello");

I advise checking out the GJC - it's got lots of interesting stuff in. (Personally I'd ignore the "alpha" tag - it's only the open source version which is "alpha" and it's based on a very stable and heavily used internal API.)

Use an extension method with method chaining.

public static List<T> WithItems(this List<T> list, params T[] items)
{
    list.AddRange(items);
    return list;
}

This would let you do this:

List<string> strings = new List<string>().WithItems("Yes");

or

List<string> strings = new List<string>().WithItems("Yes", "No", "Maybe So");

Update

You can now use list initializers:

var strings = new List<string> { "This", "That", "The Other" };

See http://msdn.microsoft.com/en-us/library/bb384062(v=vs.90).aspx

For a single item enumerable in java it would be Collections.singleton("string");

In c# this is going to be more efficient than a new List:

public class SingleEnumerator<T> : IEnumerable<T>
{
    private readonly T m_Value;

    public SingleEnumerator(T value)
    {
        m_Value = value;
    }

    public IEnumerator<T> GetEnumerator()
    {
        yield return m_Value;
    }

    IEnumerator IEnumerable.GetEnumerator()
    {
        yield return m_Value;
    }
}

but is there a simpler way using the framework?

You can also do

new List<string>() { "string here" };

I would just do

var list = new List<string> { "hello" };

Try var

var s = new List<string> { "a", "bk", "ca", "d" };

If someone landed on this page and trying to add object instead of string, then this worked for me.

new List<myObj> { new myObj{propertName=propstryValue }
, new myObj{propertName=propstryValue }, new myObj{propertName=propstryValue }
};

You need to create an inheritor from the List<> class

    public class SingletonList<T> : List<T>
    {
        public SingletonList(T element) : base(1)
        {
            this.Add(element);
        }
    }

and you can use it instead of the base List<> class

var singletonList = new SingletonList<string>("Hello World!");