How do I tell request getparameter to treat null value as 0?-CodePudding

So I am currently doing a crud in spring boot and I am stuck at this place where i want to treat null id as 0, I have tried below version and it returns

`java.lang.NumberFormatException: For input string: ""`

   @ResponseBody
    public String checkMobileEmail(HttpServletRequest req, Model model) {
        String mobile = req.getParameter("mobile");
        String email = req.getParameter("email");
        Long id = Long.parseLong(req.getParameter("id"));
        if (req.getParameter("id").equals("")) {
            id  = 0L;
        } 
        System.err.println("id : "   id   " mobile : "   mobile   " email: "   email);
        return service.findByEmailAndMobile(email,mobile,id);
    }

CodePudding user response：

You must avoid Long.parseLong(req.getParameter("id")); before the if condition as follows:

@ResponseBody
public String checkMobileEmail(HttpServletRequest req, Model model) {
   String mobile = req.getParameter("mobile");
   String email = req.getParameter("email");
   String idParameter = req.getParameter("id");
   Long id = 0L;
   if (idParameter != null && !idParameter.equals("")) {
       id = Long.parseLong(idParameter);
   } 
   System.err.println("id : "   id   " mobile : "   mobile   " email: "   email);
   return service.findByEmailAndMobile(email,mobile,id);
}

CodePudding user response：

You need to check if id is empty or null before calling Long.parseLong or it throws an exception.

Long id;
if (StringUtils.hasText(req.getParameter("id")) {
    Long.parseLong(req.getParameter("id"));
} else {
    id  = 0L;
}

You will still end up with an exception if the parameter is neither empty/null or a number. I would recommend to catch the exception and handle it appropriately.

try {
    Long.parseLong(req.getParameter("id"))
} catch(NumberFormatException e) {
    // log.warn(e) 
    return Collections.emptyList();
}