code: public Object getControlValue()
      {
          int iIndex = this.getSelectedIndex();
          try   {
              FieldTable table = m_record.getTable();
              if (m_strIndexValue != null)
                  if (iIndex != 0)
                      if (table.get(iIndex - 1) != null)  // I use get, so the index matches the index of JComboBox
              {
                  FieldInfo field = m_record.getField(m_strIndexValue);
                  if (field == null)
                      field = m_record.getField(0);
                  return field.getData();
              }
          } catch (Exception ex)  {
              ex.printStackTrace();
          }
          if (iIndex == 0)
              return null;    // None selected.
          return this.getSelectedItem();
      }
docs: Get this component's value as an object that FieldInfo can use.
  @return This component's raw data.