JCheckBox in a JList

[Gregg Bolinger]

I am trying to make a JList of JCheckBoxes. Here is the code

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class ListTest extends JFrame {

public ListTest() {
super("Hello");

this.getContentPane().setLayout(new BorderLayout());

Object[] temp = {"Option 1", "Option 2", "Option 3"};

JList theList = new JList(temp);
ListRenderer ren = new ListRenderer();
theList.setCellRenderer(ren);

this.getContentPane().add(theList);



addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}});

}


public static void main(String[] args) {

ListTest test = new ListTest();
test.setBounds(20, 20, 400, 400);
test.setVisible(true);



}

class ListRenderer extends JCheckBox implements ListCellRenderer {
    
    public ListRenderer() {
        setOpaque(true);
        setHorizontalAlignment(CENTER);
        setVerticalAlignment(CENTER);
        
    }
    public Component getListCellRendererComponent(
        JList list,
        Object value,
        int index,
        boolean isSelected,
        boolean cellHasFocus)
    {
        if (isSelected) {
            setBackground(list.getSelectionBackground());
            setForeground(list.getSelectionForeground());
        } else {
            setBackground(list.getBackground());
            setForeground(list.getForeground());
        }

        this.setText(value.toString());
        
        return this;
    }
}   


}

It comiles and runs, and I can see the Checkboxes with the correct text, however, I can't click on the check boxes. When I click the checks, they don't get checked. Any ideas?

[Travis Kline]

1. Create an Object to retain the checkbox's state, generate accessors, override toString(), etc
public ListCheckBox(Object newObject) {
aObject = newObject;
isSelected = false;
}
then add this object to your data model
DefaultListModel aModel = new DefaultListMode();
aModel.addElement(new ListCheckBox(newElement));
.
.
theList.setModel(aModel);

2. In your list cell renderer's getListCellRendererComponent, change the state of the checkbox:

this.setSelected(((ListCheckBox) value).isSelected());
3. Add a mouselistener to your list and upon mouseClicked:
public void doCheck() {
ListCheckBox item =
(ListCheckBox) getSelectedValue();
item.setSelected(!item.isSelected());
repaint();
}
This is should start you in the right direction but you'll probably have to do a lot of tweeking to get it to behave the way you want.

[Nathan Pruett]

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