setting a default enabled radiobutton in a JTable

Question

I used this guide in order to make JTable that would handle radio buttons. Works fine except i need to enable a default enabled button.

there can be n rows. I've tried to enable it through the default table model, the Object[][], the table, and i tried enabling the button before adding it to the Object[][]. I couldn't figure out how(if it is possible) to do it with the buttongroup.

to find the default enabled button i have to compare the button text to a string(this part works).

Answer 1

Not sure that I am interpreting the question correctly. You can use JRadioButton constructor to set selection, for example the snippet (based on OP code sample) will set selected button "B":

dm.setDataVector(new Object[][] { { "Group 1", new JRadioButton("A") },
    { "Group 1", new JRadioButton("B", true) },
    { "Group 1", new JRadioButton("C") },
    { "Group 2", new JRadioButton("a") },
    { "Group 2", new JRadioButton("b") } }, new Object[] {
    "String", "JRadioButton" });

You can also change selection like this:

((JRadioButton) dm.getValueAt(0, 1)).setSelected(true);

You can also use ButtonGroup.setSelected() method.

EDIT: eliminate components from model

The model should contain data rather than components. Storing components in the model defeats the idea of renderers and editors. For more details see Editors and Renderers and Swing Models and Renderers. Check out the following example the mimics button group behavior in the model:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.plaf.*;
import javax.swing.table.*;

public class ButtonGroupMockupTest {
    private static void createAndShowGUI() {
        DefaultTableModel model = new DefaultTableModel(new Object[][] {
                { "Group 1", Boolean.FALSE }, { "Group 2", Boolean.FALSE },
                { "Group 3", Boolean.FALSE } },
                new Object[] { "Name", "State" }) {

            private static final long serialVersionUID = 1L;

            @Override
            public Class getColumnClass(int col) {
                if (col == 1)
                    return Boolean.class;
                return super.getColumnClass(col);
            }

            @Override
            public void setValueAt(Object value, int row, int col) {
                super.setValueAt(value, row, col);
                if (col == 1 && value.equals(Boolean.TRUE))
                    deselectValues(row, col);
            }

            private void deselectValues(int selectedRow, int col) {
                for (int row = 0; row < getRowCount(); row++) {
                    if (getValueAt(row, col).equals(Boolean.TRUE)
                            && row != selectedRow) {
                        setValueAt(Boolean.FALSE, row, col);
                        fireTableCellUpdated(row, col);
                    }
                }
            }
        };

        JTable table = new JTable(model);
        table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        table.setDefaultRenderer(Boolean.class, new BooleanRadionRenderer());
        table.setDefaultEditor(Boolean.class, new BooleanRadioEditor());

        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new JScrollPane(table));

        f.pack();
        f.setLocationByPlatform(true);
        f.setVisible(true);
    }

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

    static class BooleanRadionRenderer implements TableCellRenderer, UIResource {
        JRadioButton radioButton;
        Border emptyBorder;

        public BooleanRadionRenderer() {
            radioButton = new JRadioButton();
            radioButton.setHorizontalAlignment(JRadioButton.CENTER);
            radioButton.setBorderPainted(true);
            emptyBorder = BorderFactory.createEmptyBorder(1, 1, 1, 1);
        }

        @Override
        public Component getTableCellRendererComponent(JTable table, Object value,
                boolean isSelected, boolean hasFocus, int row, int col) {
            if (isSelected) {
                radioButton.setBackground(table.getSelectionBackground());
                radioButton.setForeground(table.getSelectionForeground());
            } else {
                radioButton.setBackground(table.getBackground());
                radioButton.setForeground(table.getForeground());
            }
            if (hasFocus)
                radioButton.setBorder(UIManager
                        .getBorder("Table.focusCellHighlightBorder"));
            else
                radioButton.setBorder(emptyBorder);

            radioButton.setSelected(((Boolean) value).booleanValue());
            return radioButton;
        }
    }

    static class BooleanRadioEditor extends AbstractCellEditor 
                                    implements TableCellEditor {
        private static final long serialVersionUID = 1L;
        private JRadioButton radioButton;

        public BooleanRadioEditor() {
            radioButton = new JRadioButton();
            radioButton.setHorizontalAlignment(JRadioButton.CENTER);
            radioButton.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) {
                    // prevent deselection to mimic button group
                    if (!radioButton.isSelected())
                        cancelCellEditing();
                    stopCellEditing();
                }
            });
        }

        @Override
        public Component getTableCellEditorComponent(JTable table, Object value,
                boolean isSelected, int row, int col) {
            radioButton.setSelected(((Boolean) value).booleanValue());
            return radioButton;
        }

        @Override
        public Object getCellEditorValue() {
            return Boolean.valueOf(radioButton.isSelected());
        }
    }   
}