Using the generic type 'System.Collections.Generic.Dictionary< TKey, TValue>' requires 2 type arguments

Question

I get the error Using the generic type 'System.Collections.Generic.Dictionary< TKey, TValue>' requires 2 type arguments with this line of code:

this._logfileDict = new Dictionary();

I am just trying to have a clear _logfileDict with no entries in it in my code, so that is why I am assigning it a new Dictionary, which will be empty, but if anybody knows some code I could use to just empty _logfileDict otherwise. Its just a dictionary declared as follows:

private Dictionary<string, LogFile> _logfileDict;

Any help is much appreciated!

Answer 1

The reason you are getting this error is because you are attempting to use the Dictionary<TKey, TValue> class which requires generic type arguments and there is no Dictionary class which does not require generic type arguments.

When using a class which uses generic type arguments you are required to supply the types you want to use whenever you declare or instantiate a variable dealing with the class.

Replace:

this._logfileDict = new Dictionary();

With:

this._logfileDict = new Dictionary<string, LogFile>();

Answer 2

There is no type Dictionary without generic parameters in the .NET Framework. You must explicitly state the type parameters when instantiating and instance of Dictionary<TKey, TValue>. In your case, _logfileDict is declared as Dictionary<string, LogFile> and therefore you must explicitly state this when you assign a new instance of it. Therefore, you must assign to _logfileDict a new instance thusly:

this._logfileDict = new Dictionary<string, LogFile>();

(Note, however, there is a System.Collections.Hashtable in the .NET Framework if you don't want to specify the type of the keys and values.)