Components inside JComboBox

[Arun Kumarr]

Hi,
I need to have a JComboBox in this fashion. On selecting the drop down,

checkbox1 text1
checkbox2 text2
.
.
.
checkboxn textn

should be displayed.

Iam very new to Swing/Awt UI stuff and I figured out that I need to add a component inside the JCombobox I create. I Don't know if I can achieve this by adding a JCheckBox component or I need to create a JPanel for this.

I have created many JCheckBox components and tried to add it and display but nothing was visible inside the JComboBox I created. I don't know how to change the default renderer for the JComboBox and make it render this kind of JComboBox.

Please take a look at the code I have written.

        JCheckBox jc1 = new JCheckBox("chart1");
        //jc1.setVisible(true);
        JCheckBox jc2 = new JCheckBox("chart2");
        //jc2.setVisible(true);
        
/*        BasicComboBoxRenderer renderer = new BasicComboBoxRenderer();
        BoxLayout bl = new BoxLayout(combo,1);
        renderer.setLayout(bl); -- I don't know how to play with the renderer here */
        
        
        
        combo.add(jc1);
        combo.add(jc2);
        //combo.setRenderer(renderer);
       // combo.setVisible(true);
        
        JPanel pane = new JPanel(new GridLayout(0, 1));
        pane.add(button);
        pane.add(combo);        
        pane.setBorder(BorderFactory.createEmptyBorder(
                                        30, //top
                                        30, //left
                                        10, //bottom
                                        30) //right
                                        );

Any Help would be deeply appreciated and please forgive me if my code was dumb.
[ June 02, 2006: Message edited by: Arun Kumarr ]

[Craig Wood]

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class CheckCombo implements ActionListener
{
    public void actionPerformed(ActionEvent e)
    {
        JComboBox cb = (JComboBox)e.getSource();
        CheckComboStore store = (CheckComboStore)cb.getSelectedItem();
        CheckComboRenderer ccr = (CheckComboRenderer)cb.getRenderer();
        ccr.checkBox.setSelected((store.state = !store.state));
    }
 
    private JPanel getContent()
    {
        String[] ids = { "north", "west", "south", "east" };
        Boolean[] values =
        {
            Boolean.TRUE, Boolean.FALSE, Boolean.FALSE, Boolean.FALSE
        };
        CheckComboStore[] stores = new CheckComboStore[ids.length];
        for(int j = 0; j < ids.length; j++)
            stores[j] = new CheckComboStore(ids[j], values[j]);
        JComboBox combo = new JComboBox(stores);
        combo.setRenderer(new CheckComboRenderer());
        combo.addActionListener(this);
        JPanel panel = new JPanel();
        panel.add(combo);
        return panel;
    }
 
    public static void main(String[] args)
    {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(new CheckCombo().getContent());
        f.setSize(300,160);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}
 
/** adapted from comment section of ListCellRenderer api */
class CheckComboRenderer implements ListCellRenderer
{
    JCheckBox checkBox;
 
    public CheckComboRenderer()
    {
        checkBox = new JCheckBox();
    }
    public Component getListCellRendererComponent(JList list,
                                                  Object value,
                                                  int index,
                                                  boolean isSelected,
                                                  boolean cellHasFocus)
    {
        CheckComboStore store = (CheckComboStore)value;
        checkBox.setText(store.id);
        checkBox.setSelected(((Boolean)store.state).booleanValue());
        checkBox.setBackground(isSelected ? Color.red : Color.white);
        checkBox.setForeground(isSelected ? Color.white : Color.black);
        return checkBox;
    }
}
 
class CheckComboStore
{
    String id;
    Boolean state;
 
    public CheckComboStore(String id, Boolean state)
    {
        this.id = id;
        this.state = state;
    }
}

[Arun Kumarr]

Thanks Craig.
You have made me watch the climax. I'll have to find out how exactly the renderer is working. :roll: