This tip will reset the checkboxes so that none are selected.

=============================================
import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class checkBox extends Applet implements
ActionListener {
CheckboxGroup cbg;
Button b;
public void init() {
add(new Label("Payment mode?"));
cbg = new CheckboxGroup();
add(new Checkbox("Visa", cbg, false));
add(new Checkbox("Mastercard", cbg, false));
add(new Checkbox("American Express", cbg, false));
add(new Checkbox("Cash", cbg, true));
add(b = new Button("clear radio"));
b.addActionListener(this);
}

public void actionPerformed(ActionEvent e) {
if (e.getSource() == b){
Checkbox current = cbg.getSelectedCheckbox();
cbg.setSelectedCheckbox( null );
current.setState( false );

}
// return false;
}
}

=============== HTML File ===================
< HTML>
< TITLE>< /TITLE>

< BODY>


< APPLET CODE="checkBox.class">
< /APPLET>

< /BODY>< /HTML>