NullPointerException if checkbox is not cheked

I am having a checkbox in html like this : 

 <input type="checkbox" name="subscribe" value="subscribe">Subscribe For Answers</input>

And in my servlet i get its value by doing something like this : 

String checked=new String();
checked=request.getParameter("subscribe");

if(!checked.isEmpty()){
            if(checked.compareTo("subscribe")==0)
            {
                ps.setInt(4, 1);
            }
}
else  {
            ps.setInt(4,0);
}

But if checkbox is not checked then it gives Null Pointer Exception.Please help to correct it.

Jon Skeet
people
quotationmark

If the checkbox is not checked, the request won't contain any subscribe parameter, so checked will be null. You want something like:

String checked = request.getParameter("subscribe");
if (checked != null && !checked.isEmpty()) {
    ...
} else {
    ...
}

As an aside, do you really want to not call ps.setInt(4, ...) at all if the parameter value is provided, but isn't "subscribe"? Currently, you've got three options:

  • Not provided: set to 0
  • Provided and equal to "subscribe": set to 1
  • Otherwise: don't set

(It's also not clear why you're using String.compare rather than String.equals...)

people

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