Sumar Columnas

[razpeitia]

Básicamente no funciona por que el modelo lo estas recién instanciando es normal que no tenga nada.

Te dejo un ejemplo completamente funcional:

Código Java:

import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.event.TableModelEvent;
import javax.swing.event.TableModelListener;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
 
public class Utils extends JPanel implements TableModelListener {
 
    private static final long serialVersionUID = 1L;
    private boolean DEBUG = false;
    private JTable table;
    private JButton okButton;
    private String[] columnNames = {"First Name", "Last Name", "Sport", "# of Years", "Vegetarian"};
    private Object[][] data = {{"Kathy", "Smith", "Snowboarding", new Integer(5), (false)},
        {"John", "Doe", "Rowing", new Integer(3), (true)},
        {"Sue", "Black", "Knitting", new Integer(2), (false)},
        {"Jane", "White", "Speed reading", new Integer(20), (true)},
        {"Joe", "Brown", "Pool", new Integer(10), (false)}};
    private TableModel model = new DefaultTableModel(data, columnNames) {
 
        private static final long serialVersionUID = 1L;
 
        @Override
        public Class<?> getColumnClass(int column) {
            return getValueAt(0, column).getClass();
        }
    };
 
    private JButton getOkButton() {
        okButton = new JButton("OK");
        okButton.addActionListener(new ActionListener() {
 
            @Override
            public void actionPerformed(ActionEvent ae) {
                TableModel model = table.getModel();
                int total = 0;
                for (int row = 0; row < model.getRowCount(); row++) { 
                    total = total + (Integer)model.getValueAt(row, 3);
                }
                System.out.print(total + "\n");
            }
        });
        return okButton;
    }
 
    public Utils() {
        super(new GridLayout(1, 0));
        model.addTableModelListener(this);
        table = new JTable(model);
        table.setPreferredScrollableViewportSize(new Dimension(500, 70));
        table.setFillsViewportHeight(true);
        JScrollPane scrollPane = new JScrollPane(table);
        add(scrollPane);
        add(getOkButton());
    }
 
    public void tableChanged(TableModelEvent e) {
        int row = e.getFirstRow();
        int column = e.getColumn();
        model = (TableModel) e.getSource();
        String columnName = model.getColumnName(column);
        Object datas = model.getValueAt(row, column);
        System.out.println("Column ---> " + columnName + ", new value is " + datas);
    }
 
    private static void createAndShowGUI() {
        JFrame frame = new JFrame("Utils");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Utils newContentPane = new Utils();
        newContentPane.setOpaque(true); // content panes must be opaque
        frame.setContentPane(newContentPane);
        frame.pack();
        frame.setVisible(true);
    }
 
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
 
            public void run() {
                createAndShowGUI();
            }
        });
    }
}