public Object getValueAt(int rowIndex, int columnIndex)
    {
        Command row = lista.get(rowIndex);
        if(0 == columnIndex) {
            return row.getVrijeme();
        }
        else if(1 == columnIndex) {
            return row.getUser();
        }
        else if(2 == columnIndex) {
            return row.getIzvrsenaKomanda();
        }
        return null;
    }