Choice ch = new Choice();
Checkbox ckbx = new Checkbox("Test");
CheckboxGroup radio = new CheckboxGroup();
Checkbox r1 = new Checkbox("A",radio,true);
Checkbox r2 = new Checkbox("B",radio,false);
Checkbox r3 = new Checkbox("C",radio,false);
public void init() {
	ch.addItem("Red");
	ch.addItem("Green");
	add(ch); add(ckbx); add(r1); add(r2); add(r3);
}

public boolean action(Event evt, Object obj) {
    if (evt.target.equals(ch)) {
	    System.out.println("Choice " +ch.getSelectedIndex()+ch.getSelectedItem());
	    return true;
    } else if (evt.target.equals(ckbx)) {
	    System.out.println("Checkbox "+ckbx.getState());
	    return true;
    } else if (evt.target instanceof Checkbox) {
	    System.out.println("Radio:" + ((Checkbox)evt.target).getLabel());
	    return true;
    } else {
	    return super.action(evt,obj);
    }
}

Source