First item in a SortedDictionary?

Question

There are many, many threads on ways to get the \"first\" item from a Dictionary, and various answers as to why such a thing is not really a good idea beca

Answer 1

The problem is that a SortedDictionary is indeed ordered by the key. But that does not mean that you can access it via index. So if you can't use LINQ:

Dim firstFR As KeyValuePair(Of DateTime, ScheduleItem)
For Each kv In FRs
    firstFR = kv
    Exit For
Next

Otherwise you could simply use First/ FirstOrDefault.

Sidenote: since a KeyValuePair(Of Tkey, TValue) is a structure, therefore a value type, it is never null/Nothing. You could check for an empty dictionary in this ugly way:

If firstFR.Equals(New KeyValuePair(Of DateTime, ScheduleItem))
    Console.WriteLine("Empty dictionary")
End If 

So it's much more readable to use If FRs.Count = 0 Then ....

---

Update: if you just want the key or value at a given index you can use:

Dim firstSchedule As Date = FRs.Keys(0)

or the first Date in it:

Dim firstDate As ScheduleItem = FRs.Values(0)

On this way you could actually get both via index even without LINQ:

Dim firstFR = new KeyValuePair(Of DateTime, ScheduleItem)(FRs.Keys(0), FRs.Values(0))

Disclaimer: according to my question here this works only if you have imported System.Linq, then Enumerable.ElementAt is used implicitly which enumerates a sequence to find an item via index if the type doesn't implement IList(Of T). So don't use it in this case.