保持初始數(shù)據(jù)不變，并獲得JTable列單元格值的總和

我向JTable（dataTable）添加了一些數(shù)據(jù)，使用按鈕單擊事件需要將最后一列特定值的總和添加到另一個JTable（summaryTable）。我需要保持dataTable數(shù)據(jù)的原樣，并將summaryTable相加。但原始數(shù)據(jù)在相加過程中會發(fā)生變化。通過保持原始數(shù)據(jù)的原樣來求和的最佳方法是什么？

Class MyApplication

`public class MyApplication {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }

    private static void createAndShowGUI() {
        JFrame frame = new JFrame("My Application");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new DataPanel());
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}`

Class DataPanel

public class DataPanel extends JPanel {
    private JButton sumButton = new JButton();
    private JTable dataTable = new JTable();
    private JTable summeryTable = new JTable();

    public DataPanel() {
        GridBagConstraints gbc = new GridBagConstraints();
        setLayout(new GridBagLayout());
        sumButton.setText("Get Sum");
        dataTable.setModel(new javax.swing.table.DefaultTableModel(
                new Object[][]{
                    {"Column", null, null, null},
                    {null,"01","T20","500"},
                    {null, "01", "R6", "250"},
                    {null, "02", "R6", "50"},
                    {"Slab", null, null, null},
                    {null, "03", "T10", "300"},
                    {null, "04", "T10", "150"}
                },
                new String[]{
                    "Member", "Bar mark", "Type & Size", "Weight"
                }
        ));
        summeryTable.setModel(new javax.swing.table.DefaultTableModel(
                new Object[][]{},
                new String[]{
                    "Type & Size", " Total Weight"
                }
        ));
        JScrollPane dTableContainer = new JScrollPane(dataTable);
        JScrollPane sTableContainer = new JScrollPane(summeryTable);
        gbc.insets = new Insets(5, 5, 5, 5);
        gbc.fill = GridBagConstraints.BOTH;
        gbc.weightx = 0.1;
        gbc.weighty = 0.1;
        add(dTableContainer, gbc);
        gbc.insets = new Insets(5, 5, 5, 5);
        gbc.fill = GridBagConstraints.BOTH;
        gbc.gridx = 0;
        gbc.gridy = 1;
        gbc.weightx = 0.1;
        gbc.weighty = 0.1;
        add(sTableContainer, gbc);
        gbc.insets = new Insets(5, 5, 5, 5);
        gbc.fill = GridBagConstraints.NONE;
        gbc.gridx = 0;
        gbc.gridy = 2;
        gbc.weightx = 0.1;
        gbc.weighty = 0.1;
        add(sumButton, gbc);
        sumButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                DefaultTableModel dataModel = (DefaultTableModel) dataTable.getModel();
                DefaultTableModel summeryModel = (DefaultTableModel) summeryTable.getModel();
                BigDecimal tWeightRsix = BigDecimal.ZERO;
                int rowCount = summeryModel.getRowCount();
                for (int j = rowCount - 1; j >= 0; j--) {
                    summeryModel.removeRow(j);
                }
                for (int i = 0; i < dataModel.getRowCount(); i++) {
                    if (dataModel.getValueAt(i, 2) == null) {
                        dataModel.removeRow(i);
                    }
                    String mark = (String) dataModel.getValueAt(i, 2);
                    if (mark.equals("R6")) {
                        BigDecimal weights = new BigDecimal((String) dataModel.getValueAt(i, 3).toString());
                        tWeightRsix = tWeightRsix.add(weights).setScale(2, RoundingMode.HALF_UP);
                    }
                }
                Object data1 = "R6";
                Object data2 = tWeightRsix;
                summeryModel.addRow(new Object[]{data1, data2});
            }
        });
    }
}