viewing exception of a class from jsp

sde · 04-26-2004, 09:38 AM

i have a customer class in a package in a web module.

cust.optEmail = (rs.getString("SVEMAL")=="Y")?true:false;

that line is throwing an exception. i'm developing with netbeans 3.6

i have that code in a try/catch block .. but i don't know how to see what the exception is.

i've tried System.out.prinln() from inside the class, but that apparently doesn't print to the web page.

how can i see the exception?

sde · 04-26-2004, 10:17 AM

cust.optEmail = rs.getString("SVEMAL")=="Y"?true:false;

that line works .. i'm still curious how to view exceptions though.

technobard · 04-26-2004, 11:32 AM

If the failure occurs while a jsp is accessing the package as a bean, I believe you can use

Code:

<%= exception.getMessage() %>

To get this to work, however, you have to know that an error occurred in the jsp page. You can use a page directive to identify an errorpage that the code branches to if it hits an error, and then from the errorpage, you can display the exception message. Note: isErrorPage="true" allows the page to access the "exception" object from the prior jsp page.

Code:

<%@ page errorPage="errorpage.jsp" %>  //in original jsp file
...

//Contents of errorpage.jsp
<%@ page isErrorPage="true" %>
<html>
<body>
The following was an exception generated by....
<blockquote>
<%= exception.getMessage() %>
</blockquote>
</body>
</html>

This comes more or less from O'Reilly's "JavaServer Pages" book. Good stuff.

sde · 04-26-2004, 11:36 AM

thanks techno!

it's really difficult to debug classes for me right now .. i know i'm missing something.

like you pointed out .. that is only if there is an exception thrown ...

i've tried to setup breaks in the class to debug a method, but it doesn't really seem to break when i run the web app.

i suppose i can setup error variables inside my class and call them in the jsp.

sde · 04-26-2004, 11:59 AM

hey cool .. i just defined a public String var in the class named 'debug'

then in my class, i put

catch(Exception e){
debug = e.toString();
}

in my jsp:
out.println(myobject.debug);

technobard · 04-26-2004, 12:00 PM

I think runtime exceptions are caught as well, if that helps.
Good luck!

Belisarius · 04-27-2004, 04:27 AM

I'm assuming you're using Tomcat.

The Exception.printStackTrace(), and anything printed with System.out.println(), are sent to the log file catalina.out. It's probably pretty good sized right now.

sde · 04-28-2004, 06:30 AM

sounds like a great tip be.

i'll look up the implementation.. thanks!

technobard · 04-28-2004, 12:48 PM

Quote:

Originally posted by sde
sounds like a great tip be.

You know I finally realized that when you write "be", it's really short for Belisarius. I thought it was either some hip jargon that I'm out of touch with or really bad grammar.

sde · 04-28-2004, 12:58 PM

you're pretty quick te