Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.programmer > #12906

Re: Exception Handling

Show all headers | View raw

On 3/10/2012 8:51 PM, Novice wrote:
> I've been trying to get my head around exception handling for the last
> few days concurrently with my efforts to start doing logging correctly.
>
> I've re-read the Java Tutorials section on exception handling. I read
> Bloch's remarks on Exception Handling in Effective Java (2nd edition)
> several days ago. I'm working my way through Stelting's Robust Java.
>
> It's time to ask some questions to make sure I'm on the right track.
>
> I'm struggling with the best way to revise some of my existing code.
> Let's consider a concrete example and then see if we can generalize to
> come up with a proper error handling strategy.
>
> I have a utility class called LocalizationUtils which basically houses
> convenience methods dealing with i18n/l10n. One of its methods is
> getResources(). It expects two parameters, a String representing the
> "base name" (the leading part of the resource file name) and a locale.

> In terms of trouble spots, I know from experience that getResources()
> will throw a MissingResourceException, which is an unchecked exception,
> if the base name is misspelled. A null value in either parameter is also
> going to make the getResources() method fail: ResourceBundle.getBundle()
> will throw a NullPointerException if either parameter is null.
>
> My objective is to code getResources() and getLocalizedText() as
> professionally as possible. If the methods fail, I want to write a clear
> message to my log and the log record needs to include a stacktrace. (I'm
> assuming that a console is not necessarily available to the operators
> running this program and I need to know where the error took place. Based
> on an article Arved suggested in another thread,
> http://www.javacodegeeks.com/2011/01/10-tips-proper-application-
> logging.html, I'm inclined to minimize "position" information - class
> name, method name, line number - in the log and instead get all of that
> from the stacktrace.)

I would not worry about the performance until you know that you
have a problem.

> Since the only exceptions I anticipate, MissingResourceException and
> NullPointerException, are unchecked exceptions, I gather than I shouldn't
> really do anything about them aside from logging when they happen.

If you only log - then what?

>                                                                    Okay,
> fair enough; I certainly don't want to display the source code to my
> user, make them enter the correct value for the baseName, make them
> recompile the program and then run it again! But when/where should I log
> the error? For instance, if I mess up my coding somehow and inadvertently
> pass a null in the baseName, should getResources() be testing its input
> parameters individually to see if they are null and write a message to
> the log if they are null from within that method? I'm inclined to say yes
> to that but I'm not sure what to do next. It seems pointless to carry on
> with getResources() since ResourceBundle.getBundle(baseName, locale)
> will fail on a NullPointerException with a null in either parameter. I
> could throw a NullPointerException so that getLocalizedText() can deal
> with it. But how do I get a stacktrace into the log if I follow that
> strategy? It's easy enough to get the stacktrace once I've caught an
> exception but I'm just talking about recognizing that an input parameter
> is null; there's no exception at that point to put in my log.
>
> If I let getResources() throw NullPointerException if either parameter is
> null, then I can let getLocalizedText() catch those NullPointerExceptions
> and get the stacktraces from the exception and write them to the log. In
> that case, I may as well just check the input parameters for nulls, and
> simply throw NullPointerException with a specific message within
> getResources(); then getLocalizedText() can have a try/catch block. The
> try/catch can detect the NullPointerException and write both the message
> and the stacktrace to the log.
>
> But I gather that you should handle the error as close to where it
> happened as possible when you can. I'd tend to prefer to handle the null
> parameter values in getResources() except that I'm not sure how to write
> the stack trace to the log before any exception has happened.

Do you need the stacktrace in that case?

> One other questions. When, if ever, should I execute System.exit() with a
> non-zero integer?

When you want to terminate the program with an error status to the
shell.

Arne

Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

Exception Handling Novice <novice@example..com> - 2012-03-11 01:51 +0000
  Re: Exception Handling Lew <noone@lewscanon.com> - 2012-03-10 18:39 -0800
    Re: Exception Handling Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-03-11 11:53 -0300
      Re: Exception Handling Lew <noone@lewscanon.com> - 2012-03-11 10:51 -0700
        Re: Exception Handling Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-03-11 16:35 -0300
    Re: Exception Handling Novice <novice@example..com> - 2012-03-11 17:05 +0000
      Re: Exception Handling Lew <noone@lewscanon.com> - 2012-03-11 10:53 -0700
        Re: Exception Handling Novice <novice@example..com> - 2012-03-11 20:36 +0000
      Re: Exception Handling Lew <noone@lewscanon.com> - 2012-03-11 11:07 -0700
        Re: Exception Handling Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-03-11 17:00 -0300
          Re: Exception Handling Novice <novice@example..com> - 2012-03-11 22:02 +0000
        Re: Exception Handling Arivald <NOSPAMarivald@interia.pl> - 2012-03-11 21:03 +0100
          Re: Exception Handling Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-03-11 18:31 -0300
        Re: Exception Handling Novice <novice@example..com> - 2012-03-11 21:54 +0000
          Re: Exception Handling Patricia Shanahan <pats@acm.org> - 2012-03-11 15:26 -0700
            Re: Exception Handling Novice <novice@example..com> - 2012-03-11 23:23 +0000
              Re: Exception Handling Lew <noone@lewscanon.com> - 2012-03-11 16:52 -0700
                Re: Exception Handling Novice <novice@example..com> - 2012-03-12 17:16 +0000
                Re: Exception Handling Lew <noone@lewscanon.com> - 2012-03-13 08:31 -0700
              Re: Exception Handling Patricia Shanahan <pats@acm.org> - 2012-03-11 17:51 -0700
                Re: Exception Handling Novice <novice@example..com> - 2012-03-12 17:26 +0000
            Re: Exception Handling Arne Vajhøj <arne@vajhoej.dk> - 2012-03-12 14:49 -0400
          Re: Exception Handling Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-03-11 20:46 -0300
            Re: Exception Handling Novice <novice@example..com> - 2012-03-12 17:43 +0000
      Re: Exception Handling Patricia Shanahan <pats@acm.org> - 2012-03-11 11:14 -0700
        Re: Exception Handling Novice <novice@example..com> - 2012-03-11 22:35 +0000
          Re: Exception Handling Lew <noone@lewscanon.com> - 2012-03-11 16:58 -0700
            Re: Exception Handling Novice <novice@example..com> - 2012-03-12 15:44 +0000
              Re: Exception Handling Gene Wirchenko <genew@ocis.net> - 2012-03-12 10:34 -0700
      Re: Exception Handling Arivald <NOSPAMarivald@interia.pl> - 2012-03-11 20:34 +0100
        Re: Exception Handling Novice <novice@example..com> - 2012-03-11 22:36 +0000
    Re: Exception Handling Arne Vajhøj <arne@vajhoej.dk> - 2012-03-12 14:41 -0400
  Re: Exception Handling Arne Vajhøj <arne@vajhoej.dk> - 2012-03-12 14:37 -0400
    Re: Exception Handling Novice <novice@example..com> - 2012-03-12 22:43 +0000
      Re: Exception Handling Lew <lewbloch@gmail.com> - 2012-03-12 16:11 -0700
      Re: Exception Handling Arivald <NOSPAMarivald@interia.pl> - 2012-03-13 00:54 +0100
        Re: Exception Handling Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-03-13 06:05 -0300

csiph-web