Question

This is a noob question, I know but I didn’t find the answer on the internet…

I got the following Dictionary :

private static Dictionary<Qb.Solution.QbDataStore.DataStoreType, string> DataStoreType2IconPath = new Dictionary<QbDataStore.DataStoreType, string>()
{
    { Qb.Solution.QbDataStore.DataStoreType.CommonData, "Common" },
    { Qb.Solution.QbDataStore.DataStoreType.ApplicationData, "Application" },
    { Qb.Solution.QbDataStore.DataStoreType.FrameData, "Frame" }
};

and then I have a method with a Qb.Solution.QbDataStore.DataStoreType dataType parameter and I got this :

if (dataType != null)
{
    collection.IconPath = DataStoreType2IconPath[dataType];
}

My question is :

If I remove the if test, and that I don’t know how (theorytically impossible) dataType is null :

1. collection.IconPath is null ?
2. it throw an exception ?

Answer 1

According to my quick test, adding a null key to a dictionary causes an ArgumentNullException and trying to retrieve a key that doesn’t exist results in a KeyNotFoundException.

namespace ConsoleApplication46
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            var d = new Dictionary<string, int>();

            d.Add(null, 1);

            Console.WriteLine(d["adam"]);
            Console.Read();
        }
    }
}

As for code reviewing how best to write it, try https://codereview.stackexchange.com/

Alternative methods include TryGetValue and ContainsKey.