C#

for (int i = 0; i < dgv_ScanStat.ColumnCount; i++)
{
  System.Type Tp = dgv_ScanStat.Columns[i].ValueType;
  bool isNumeric =
      Tp == typeof(byte) ||
      Tp == typeof(System.Int16) ||
      Tp == typeof(System.Int32) ||
      Tp == typeof(System.Int64) ||
      Tp == typeof(sbyte) ||
      Tp == typeof(System.UInt16) ||
      Tp == typeof(System.UInt32) ||
      Tp == typeof(System.UInt64) ||
      Tp == typeof(float) ||
      Tp == typeof(double) ||
      Tp == typeof(decimal);

  if (isNumeric)
  {
    dgv_ScanStat.Columns[i].DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleRight;
  }
}

class ProcedureExecution
{
     IDataAccess dataAccess;
     public ProcedureExecution(IDataAccess dataAccess)
     {
         this.dataAccess = dataAccess;
     }

     public void ExecProc(int vidID)
     {
          try
          {
              dataAccess.Execute("blah",vidID);
          }
          catch (Exception e)
          {
              //Console.WriteLine("error: " + e.ToString());
          }
     }
}

Mohammad Dayyan wrote:

Object reference not set to an instance of an object

Mohammad Dayyan wrote:

I'm sure that there is a data in it

JoeRip wrote:

Which line throws the exception?

XElement newXmlNode = (XElement)Clipboard.GetData("XElement");

To guarantee the thread safety of the Queue, all operations must be done through this wrapper only.

Enumerating through a collection is intrinsically not a thread-safe procedure. 
Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception.
To guarantee thread safety during enumeration, 
you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.