How to access Dictionary<TKey, TValue>.Item Property in C#

Question

I am new to the C#/.Net and have a problem with class Dictionary. I created a dictionary of groups and added an item (or more items, now it doesn't matter):

Dictionary<int, ListViewGroup> groups = new Dictionary<int, ListViewGroup>();
groups.Add(1, new ListViewGroup("Group1"));

I would like to find my group by its key. In documentation it says that there is an Item property which I can access directly or by indexer. However, when I try to access it directly:

ListViewGroup g = groups.Item(1);

my compiler says that there is no definition for property Item in Dictionary class. Can anyone explain this to me please? Thank you.

Answer 1

Item is an indexer, you can verify it by looking at definition:

public TValue this[TKey key] { get; set; }

Simply use indexer syntax to access elements by key:

ListViewGroup g = groups[1]; 
Console.WriteLine (g.Header); //prints Group1 

Note: this will throw KeyNotFoundException if no entry with such key would be present in groups dictionary. For example groups[2] will throw an exception in your case.