CHECK BOX GROUP

It is possible to create a set of mutually exclusive check boxes in which one and only one
check box in the group can be checked at any one time. These check boxes are often called
radio buttons, because they act like the station selector on a car radio—only one station can be selected at any one time. To create a set of mutually exclusive check boxes, you must
first define the group to which they will belong and then specify that group when you
construct the check boxes. Check box groups are objects of type CheckboxGroup. Only
the default constructor is defined, which creates an empty group.
You can determine which check box in a group is currently selected by calling
getSelectedCheckbox( ). You can set a check box by calling setSelectedCheckbox( ).
These methods are as follows:
Checkbox getSelectedCheckbox( )
void setSelectedCheckbox(Checkbox which)
Here, which is the check box that you want to be selected. The previously selected check
box will be turned off.
Here is a program that uses check boxes that are part of a group:
// Demonstrate check box group.
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
/*


*/
public class CBGroup extends Applet implements ItemListener {
String msg = "";
Checkbox Win98, winNT, solaris, mac;
CheckboxGroup cbg;
public void init() {
cbg = new CheckboxGroup();
Win98 = new Checkbox("Windows 98/XP", cbg, true);
winNT = new Checkbox("Windows NT/2000", cbg, false);
solaris = new Checkbox("Solaris", cbg, false);
mac = new Checkbox("MacOS", cbg, false);
add(Win98);
add(winNT);
add(solaris);
add(mac);
Win98.addItemListener(this);

winNT.addItemListener(this);
solaris.addItemListener(this);
mac.addItemListener(this);
}
public void itemStateChanged(ItemEvent ie) {
repaint();
}
// Display current state of the check boxes.
public void paint(Graphics g) {
msg = "Current selection: ";
msg += cbg.getSelectedCheckbox().getLabel();
g.drawString(msg, 6, 100);
}
}