JCheckBox value in JTable

Question

JCheckBox is checked but it still shows its value as false when i use system.out.print .If the focus is lost but with JCheckBox still checked then it returns true. i.e when i check 2 checkbox the result showed is for first checkbox. the status of second checkbox is not shown. complete prog is shown below: pls run the prog and do rectify my mistake. any help is welcome.

public class check extends JFrame {

    public check() {
        setBounds(00, 40, 400, 400);
        Color c = new Color(160, 200, 100);
        getContentPane().setBackground(c);
        Color c3 = new Color(0, 50, 50, 2);
        setTitle("MARKING OF TARGET HABITATION");
        setUndecorated(true);
        getRootPane().setWindowDecorationStyle(JRootPane.PLAIN_DIALOG);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        String[] columnNames = {"Country", "Capital", "Population in Millions",
            "Democracy"};
        Object[][] data = {
            {"USA", "Washington DC", 280, new Boolean(false)},
            {"Canada", "Ottawa", 32, new Boolean(false)},
            {"United Kingdom", "London", 60, new Boolean(false)},
            {"Germany", "Berlin", 83, new Boolean(false)},
            {"France", "Paris", 60, new Boolean(false)},
            {"Norway", "Oslo", 4.5, new Boolean(false)},
            {"India", "New Deli", 1046, new Boolean(false)}
        };

        final JTable table = new JTable(data, columnNames) {

            public boolean isCellEditable(int rowIndex, int colIndex) {
                return (colIndex == 3);//Disallow the editing of any cell
            }
        };
        table.getColumnModel().getColumn(3).setCellEditor(new CheckBoxCellEditor());
        table.getColumnModel().getColumn(3).setCellRenderer(new CWCheckBoxRenderer());
        JScrollPane scrollPane = new JScrollPane(table);
        JButton button = new JButton("check");
        button.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                boolean[] rsel = new boolean[table.getRowCount()];
                for (int i = 0; i < table.getRowCount(); i++) {
                    rsel[i] = (boolean) table.getValueAt(i, 3);
                    if (rsel[i]) {
                        System.out.println("checkbox selected at row"
                            + " " + i + "is" + rsel[i]);
                        for (int col = 0; col <= 3; col++) {
                            table.getValueAt(i, col);
                            System.out.println("data at row" + " "
                                + i + "is" + table.getValueAt(i, col));
                        }
                    }
                }
            }
        });
        JPanel buttonpanel = new JPanel();
        buttonpanel.add(button);
        add(scrollPane, BorderLayout.CENTER);
        add(buttonpanel, BorderLayout.SOUTH);
        Color c1 = new Color(160, 200, 100);
        table.setBackground(c1);
        buttonpanel.setBackground(c1);
        setBackground(c1);
        setVisible(true);
    }

    public static void main(String args[]) {
        new check();

    }

    class CheckBoxCellEditor extends AbstractCellEditor implements TableCellEditor {

        private static final long serialVersionUID = 1L;
        protected JCheckBox checkBox;

        public CheckBoxCellEditor() {
            checkBox = new JCheckBox();
            checkBox.setHorizontalAlignment(SwingConstants.CENTER);
            // checkBox.setBackground( Color.white);
        }

        public Component getTableCellEditorComponent(
            JTable table,
            Object value,
            boolean isSelected,
            int row,
            int column) {
            checkBox.setSelected(((Boolean) value).booleanValue());
            return checkBox;

        }

        public Object getCellEditorValue() {
            return Boolean.valueOf(checkBox.isSelected());
        }
    }

    class CWCheckBoxRenderer extends JCheckBox implements TableCellRenderer {

        private static final long serialVersionUID = 1L;
        Border border = new EmptyBorder(1, 2, 1, 2);

        public CWCheckBoxRenderer() {
            super();
            setOpaque(true);
            setHorizontalAlignment(SwingConstants.CENTER);
        }

        public Component getTableCellRendererComponent(
            JTable table,
            Object value,
            boolean isSelected,
            boolean hasFocus,
            int row,
            int column) {
            if (value instanceof Boolean) {
                setSelected(((Boolean) value).booleanValue());
                //setEnabled(table.isCellEditable(row, column));
                setForeground(table.getForeground());
                setBackground(table.getBackground());

            }
            return this;
        }
    }
}

Answer 1

For reference, this sscce illustrates @ StanislavL's point. Note that autoboxing, introduced in Java 5, results in column three having type Boolean. At run time, the overridden getColumnClass() will return Boolean.class for index CHECK_COL. Finally, Swing GUI objects should be constructed on the event dispatch thread.

import java.awt.BorderLayout;
import java.awt.EventQueue;
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.table.DefaultTableModel;

public class Check extends JFrame {

    private static final int CHECK_COL = 3;

    public Check() {
        setTitle("MARKING OF TARGET HABITATION");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        String[] columnNames = {
            "Country", "Capital", "Population in Millions", "Democracy"};
        Object[][] data = {
            {"USA", "Washington DC", 280, true},
            {"Canada", "Ottawa", 32, false},
            {"United Kingdom", "London", 60, false},
            {"Germany", "Berlin", 83, false},
            {"France", "Paris", 60, false},
            {"Norway", "Oslo", 4.5, false},
            {"India", "New Deli", 1046, false}
        };
        DefaultTableModel dtm = new DefaultTableModel(data, columnNames) {

            @Override
            public Class getColumnClass(int col) {
                return getValueAt(0, col).getClass();
            }

            @Override
            public boolean isCellEditable(int rowIndex, int colIndex) {
                return (colIndex == CHECK_COL);
            }
        };
        final JTable table = new JTable(dtm);
        JScrollPane scrollPane = new JScrollPane(table);
        JButton button = new JButton("check");
        button.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                for (int row = 0; row < table.getRowCount(); row++) {
                    Boolean b = ((Boolean) table.getValueAt(row, CHECK_COL));
                    if (b.booleanValue()) {
                        System.out.print("row " + row + " is " + b + ": ");
                        for (int col = 0; col < table.getColumnCount(); col++) {
                            System.out.print(table.getValueAt(row, col) + " ");
                        }
                        System.out.println();
                    }
                }
            }
        });
        JPanel buttonpanel = new JPanel();
        buttonpanel.add(button);
        add(scrollPane, BorderLayout.CENTER);
        add(buttonpanel, BorderLayout.SOUTH);
        pack();
        setLocationByPlatform(true);
        setVisible(true);
    }

    public static void main(String args[]) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new Check();
            }
        });
    }
}

Answer 2

May be it's better to override getColumnClass in the model to return Boolean. Default Renderer/Editor handle the case and you can see/use checkbox.