How to make file upload in struts2 optional?

Question

I'm building a web application with Struts2. There's a small part that involves File Upload. The File Upload works well. However a NullPointerException is thrown when I choose to NOT upload a file. The only way I can handle this in code, is by catch(NullPointerException NPE) . And a part of the code gets repeated. I wish to avoid this.

Is there any way I can handle a NULL for a file upload in Struts2?

My HTML file:

<s:file style="height:auto;width:550px;display:inline;align:center;" name="userImage" cssClass="text input" onchange="checkFile(this)"/>

My Java action code which handles this:

try{
String filePath = servletRequest.getSession().getServletContext().getRealPath("/");
System.out.println("Server path:" + filePath);
File fileToCreate = new File(filePath, this.userImageFileName);
FileUtils.copyFile(this.userImage, fileToCreate);}

catch(NullPointerException NPE){//if I choose to NOT upload a file}
catch(Exception E){//some code}

I've tried the getUserImage()==null but it does not help. Do I absolutely have to handle the rest of the code inside the catch(NullPointerException NPE) block?

Answer 1

Most likely, the NullPointerException is thrown at one of the following two lines

File fileToCreate = new File(filePath, this.userImageFileName);
FileUtils.copyFile(this.userImage, fileToCreate);

because this.userImageFileName and/or this.userImage is null, if you do not upload a file.

So, try this:

if(this.userImageFileName != null && this.userImage != null){
   File fileToCreate = new File(filePath, this.userImageFileName);
   FileUtils.copyFile(this.userImage, fileToCreate);
}

Now, no NullPointerException should occure, since you checked for null in advance.