public   class  MyForm  extends  ActionForm{
   private  String mychckbx;
   public   void  setMychckbx(String value){
     if (value== null ){
      mychckbx="false";
    }  else {
      mychckbx=value;
    }

  }
   public  String getMychckbx(){
     return  mychckbx;
  }
   public   void  reset(ActionMapping actionMapping, HttpServletRequest httpServletRequest){
    mychckbx=getStatusFromDatabase();
  }

<html:form action="/someAction.do">
  <html:checkbox property="mychckbx"/>
</html:form>

String mychckbx=httpServletRequest.getParameter("mychckbx");
 if (mychckbx== null ){
  actionForm.setMychckbx("false");
}

 public   class  TestForm   extends  ValidatorForm {

   private  List items;

  ...
  
   public   void  reset(ActionMapping mapping, HttpServletRequest request) {
     for  (Iterator it = items.iterator(); it.hasNext();) {
      MyClass myClass = (MyClass)it.next();
      // Предположим, что есть свойство boolean myClass.myValue
      myClass.myValue = false;
    }
  }