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

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.