How do I fix a java.lang.NumberFormatException: for String " " in my servlet?

Question

I keep running into the same error after trying to parse a String parameter I pulled from a corresponding jsp and make them into an integer and a float. In my web application I have java classes where the values I'm trying to parse are an integer and a float, but I can't seem to find a way to parse them and have my servlet work the way I'd like it to. Here's the code I used in my servlet:

        //get Parameter from newStudentPage.jsp
        String id = request.getParameter("stuId");
        String fName = request.getParameter("fName");
        String lName = request.getParameter("lName");
        String street = request.getParameter("street");
        String city = request.getParameter("city");
        String state = request.getParameter("state");
        String zip = request.getParameter("zip");
        String email = request.getParameter("email");
        String gpa = request.getParameter("gpa"); 

        int Zip = Integer.valueOf(zip);
        float GPA = Float.parseFloat(gpa);

        //Use RequestDispatcher to forward to jsp's
        RequestDispatcher rd = request.getRequestDispatcher("newStudentLoginPage.jsp");
        RequestDispatcher rd2 = request.getRequestDispatcher("newStudentSectionAddDrop.jsp");

        //Create Student object and fill with paramater data
        Student s2 = new Student();
        s2.setstuId(id);
        s2.setfName(fName);
        s2.setlName(lName);
        s2.setstreet(street);
        s2.setcity(city);
        s2.setstate(state);
        s2.setzip(Zip);
        s2.setemail(email);
        s2.setgpa(GPA);

        //Put Student object into Session
        HttpSession ses2 = request.getSession();
        ses2.setAttribute("s2", s2);           
        if(id.equals("")||fName.equals("")||lName.equals("")||street.equals("")||city.equals("")||state.equals("")||zip.equals("")||email.equals("")||gpa.equals("")){
            rd.forward(request, response);
        }else{
            rd2.forward(request, response);
        }

Can anyone please offer my some insight to what I'm doing wrong?

It sounds like either zip or gpa is blank or a space (since we don't have a stack trace, just a portion of the stack trace as your question title). As a result, parsing "" or " " will be a problem. Either you need to do an empty check or make sure that any pages leading to this one require a zip and gpa. — MrMike
– MrMike, Commented Jul 27, 2014 at 0:21
I tried before using zip == 0 and gpa == 0 and neither worked in my if statement that checked for null values. I also tried to parse them using Integer.parseInt(zip) and Float.parseFloat(gpa) inside my if statement and that didn't work either. What other method should I use instead. — Paulieknucklez1
– Paulieknucklez1, Commented Jul 27, 2014 at 1:03

james · Accepted Answer · 2014-07-27 00:24:13Z

2

One or all of these lines can cause the exception:

int Zip = Integer.valueOf(zip);
float GPA = Float.parseFloat(gpa);

You need to check if String zip or gpa can always be converted into a number. What if the user enters nothing, i.e "", " "or a non-number like seven777 ? Those conditions will cause a NumberFormatException.

answered Jul 27, 2014 at 0:24

james

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Ale Zalazar · Accepted Answer · 2014-07-27 00:48:21Z

2

You should catch the exception and do something, i.e. provide a default value, ask the user to enter a valid value, etc...

    Float floatGpa = null;
    try {
        floatGpa = Float.parseFloat(gpa);
    } catch (NumberFormatException e) {
        //do something
    }

answered Jul 27, 2014 at 0:48

Ale Zalazar

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