public void tableChanged(javax.swing.event.TableModelEvent tme) {
          DefaultTableModel tm = (DefaultTableModel) tme.getSource();
          int col = tme.getColumn();
          int row = tme.getFirstRow();
          String valCel = (String) tm.getValueAt(tme.getFirstRow(), 0);

          if (tme.getType() == 0 && (col == 2 || col == 3)) {
            calculaSumas();
          }
        }