C#

private void LoadFileNames(string folder, string extension, ListBox lb)
    {
    string[] files = Directory.GetFiles(folder, "*" + extension);
    lb.DataSource = files.Select(f => Path.GetFileNameWithoutExtension(f)).ToList();
    }

LoadFileNames(@"D:\Temp", ".txt", myListBox);

string greetings = "Hello!";
private void MyMethod(greetings g)
   {

string greetings = "Hello!";
private void MyMethod(string g)
   {
   ...
   }
   ...
   MyMethod(greetings);

using System.Windows.Forms;

<MenuItem ContextMenu="{StaticResource MyContextMenu}">
    <MenuItem/>
    <MenuItem/>
    <MenuItem/>
</MenuItem>

Gilbert Consellado wrote:

is there way to fix the exception without removing the parameter i added to the class

var classObject = new ClassObject();

var classObject = new ClassObject(myParameterValue);

public classObject(SomeClass parameterName)
   {
   ...

public classObject()
   {
   ...

var classObject = new ClassObject(parameterValue);
dictionary.Add(id, new MemoryStream());
///then add the object stream here to the created storage on the dictionary

var retriveObject = dictionary[id] as ClassObject; //The runtime error while happen here

    Dictionary<int, MemoryStream> dictionary = new Dictionary<int, MemoryStream>();
    var classObject = new ClassObject("hello");
    int id = 666;
    dictionary.Add(id, new MemoryStream());
    var retriveObject = dictionary[id] as ClassObject;
    }


public class ClassObject : MemoryStream
    {
    public ClassObject(string s) { }
    }

[Serializable]
public class ClassObject : MemoryStream
{
    //Must be present for serialization to work!
    internal ClassObject() { }

    public ClassObject(string s) { }
}