How to add a DataCell to a DataRow?

In my code I want that the user can add a new DataCell to a DataRow in my DataTable. But I dont know how I can add a single DataCell. My Code looks like this, but it didnt work:

  List<DataRow> RowList = [
    DataRow(cells: <DataCell>[
      DataCell(Text('Column 1')),
      DataCell(Text('Column 2')),
      DataCell(Text('Column 3')),
    ]),
  ];
  
  void _addDataCell() {
    RowList.add(DataCell(Text('Column 4')))
  }