ServletFileUpload java.lang.NullPointerException

Posted on 2008-10-16
Last Modified: 2013-11-24

I have a File upload on a jsp page, if I do not upload and press submit, it throws java.lang.NullPointerException

I use

boolean isMultipart = ServletFileUpload.isMultipartContent(request);
then upload file

Can ServletFileUpload == null then redirect to another jsp page?

Question by:techques
  • 2
LVL 20

Expert Comment

by:chaitu chaitu
ID: 22737430
you can put some javascript validation for this?

alert("Please upload file")
redirect to ur jsp;;

Author Comment

ID: 22737702
I use the following code to check whether the upload file is in the right format extension.

However, once I use it and it cannot pass the variable to servlet and throw nullpointerexception.

How can I fix it?

<script language="JavaScript">

    extArray = new Array(".jpg", ".png", ".gif");

    function LimitAttach(form, file) {

    allowSubmit = false;

    if (!file) return;

    while (file.indexOf("\\") != -1)

    file = file.slice(file.indexOf("\\") + 1);

    ext = file.slice(file.indexOf(".")).toLowerCase();

    for (var i = 0; i < extArray.length; i++) {

    if (extArray[i] == ext) { allowSubmit = true; break; }


    if (allowSubmit) return true;


    alert("Please only upload files that end in types:  "

    + (extArray.join("  ")) + "\nPlease select a new "

    + "file to upload and submit again.");

    return false;




OnSubmit="return LimitAttach(this.form, this.form.myimage.value)"



boolean isMultipart = ServletFileUpload.isMultipartContent(request);

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LVL 20

Accepted Solution

chaitu chaitu earned 50 total points
ID: 22737907
can't you write like this
if (allowSubmit)
document.forms[0].action="/ServletFileUpload?action=fileupload&file="+the file u want to upload
return true;

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