Question

http://localhost:8080/file.jsp?arg1=&arg2=11

runs successfully

http://localhost:8080/file.jsp?arg1=&arg2=

(empty value for argument ‘arg2’)

shows 500 Internal Server Error

The value of ‘arg2’ is used by an ‘int‘ variable in ‘jsp‘ using Integer.parseInt(request.getParameter("arg2")

How to fix it?

Answer 1

It is because you are trying to parse “” with Integer.parseInt

Check Integer parseInt() API

When you do not pass any values Like below

http://localhost:8080/file.jsp?arg1=&arg2=

Empty string will be passed in http request parameters.

So, better put empty check when parsing integer from string.

int arg2 = !"".equals(request.getParameter("arg2")) ? 
                Integer.parseInt(request.getParameter("arg2")): 0;