FIGURE 24-2
Sample output from the CheckboxDemo applet
CheckboxGroup
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.*;
/*
<applet code="CBGroup" width=250 height=200>
</applet>
*/
public class CBGroup extends Applet implements ItemListener {
String msg = "";
Checkbox winXP, winVista, solaris, mac;
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