addButton.setOnAction(new EventHandler<ActionEvent>() {

        @Override
        public void handle(ActionEvent event) {
            Operation operation = new Operation();
            operation.addRecord(dateTextField, distanceTextField, lpgAmountTextField, lpgPriceTextField,
                    petrolAmountTextField, petrolPriceTextField, paidLabel, savingLabel, gasEfficiencyLabel,
                    contentTable, totalSavingsLabel);

            operation.totalPaidSaving(contentTable, totalSavingsLabel);
        }

    });

@SuppressWarnings("unchecked")
public void configurateTable() {

    TableColumn<GasRecords, String> savingColumn = new TableColumn<GasRecords, String>(SAVING_COLUMN);
    savingColumn.setCellValueFactory(new PropertyValueFactory<>("saving"));


    contentTable.getColumns().addAll(dateColumn, distanceColumn, lpgAmountColumn, lpgPriceColumn, petAmountColumn,
            petPriceColumn, paidColumn, savingColumn, gasEfficiencyColumn);

}

public void totalPaidSaving(TableView<GasRecords> cT, Label tSL) {

    String totalSavingValue = "0";

    //the code that calculates the sum of the values ​​of a particular column

    tSL.setText(String.format("%.2f zł", totalSavingValue));
    }