The NetBeans generate code like Logger.getLogger(svr.class.getName()).log(Level.SEVERE, null, ex);
to output exception in catch.It will display in console.
After I
The logging system in NetBeans is based on the standard JDK's java.util.logging and complies to it as much as possible. In order to output error messages to a file, you can provide your own logging properties file on the classpath of your project.
See the following links for more info :
Netbeans logging : http://bits.netbeans.org/dev/javadoc/org-openide-util/org/openide/util/doc-files/logging.html
Java Util logging with logging properties file sample : http://www.javapractices.com/topic/TopicAction.do?Id=143