Question

Task.Factory.StartNew((param,param2) => { Console.WriteLine("Test"); },
                                        TaskCreationOptions.None);

Error 1 Delegate ‘System.Action’ does not take 2 arguments

I am getting the above error. Couldn’t understand what’s going wrong.

Edited: Why it is accepting single parameters then

  Task.Factory.StartNew((param1) =>
            {
                for (int j = 0; j < 10; j++)
                {
                    Console.WriteLine(string.Format("Task : {0}, outputing {1}- {2}",
                       param1, j.ToString(), param1));
                }
            }, string.Format("Tast Count " + ic++.ToString()));

Answer 1

There are several overloads to the Task.Factory.StartNew method. The two you’ve mentioned in your question are:

Task.Factory.StartNew(Action, TaskCreationOptions)
Task.Factory.StartNew(Action<Object>, Object)

The methods do considerably different things. The item of note, though, is the difference between Action and Action<object>. Lambdas are essentially anonymous methods, so to get a visual of what these are, let’s convert them to method signatures.

Action                 -> void AnonymousMethod()
Action<object>         -> void AnonymousMethod(object f)
Action<object, object> -> void AnonymousMethod(object f, object s)

In your first example, which doesn’t compile, it is equivalent to the last one. There is no overload for Task.Factory.StartNew that takes multiple parameters.