public FieldDescription GetField( 
   int index
)

{
  // field access
  var flds = tableView.GetFields();
  var fldIdx = tableView.GetFieldIndex("STATE_NAME");
  var fldDesc = tableView.GetField(fldIdx);
}

{
  // get active field, active field name
  var activeFieldIdx = tableView.ActiveFieldIndex;
  var fldDesc = tableView.GetField(activeFieldIdx);
  var fldName = fldDesc.Name;

  // set active field by name
  tableView.SetActiveField("STATE_NAME");

  // or set active field by index
  tableView.SetActiveField(3);
}