C#

public struct SomeStruct
{
    public Int32 t1;
    public Int32 t2;

    public SomeStruct(Int32 t1_, Int32 t2_)
    {
        t1= t1_;
        t2= t2_;
    }
}

private void Thread1(Int32 T1, Int32 T2)
{
     object t = new SomeStruct(T1, T2);
     Thread RunningThread= new Thread(Mathod1);
     RunningThread.Start(t);
}

public void Mathod1(object ap)
{
     // Here the 'invalid case' exception !!!! 
     Mathod2(((SomeStruct)ap).T1, ((SomeStruct)ap).T2);
}2

static void Main(string[] args)
       {
           int choice = 0;

           if (args.Length == 0)
               choice = 1;
           else
               choice = 2;

           switch(choice)
           {
               case 1:
                   {
                       string[] text = Directory.GetFiles("allText");
                       Console.WriteLine(DateTime.Now.ToString());
                       foreach (string fileName in text)
                       {
                           string substring = fileName.Substring(8);


                           ReadData_Logic rd_l = new ReadData_Logic(substring);
                           rd_l.runThreadsAndDecrypt();
                           rd_l.printKey(substring.Substring(0, fileName.Length - 15).Insert(0, "encryptedKey\\") + "_result.txt");

                       }
                       Console.WriteLine(DateTime.Now.ToString());
                   } break;

               case 2:
                   {
                       Console.WriteLine(DateTime.Now.ToString());
                       string fileName = args[0];
                       Console.WriteLine(fileName); <big><--- for debug, here i do see the correct file name</big>
                       ReadData_Logic rd_l = new ReadData_Logic(fileName);
                       rd_l.runThreadsAndDecrypt();
                       rd_l.printKey(fileName + "_result.txt");

                       Console.WriteLine(DateTime.Now.ToString());
                   } break;
           }

       }