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

Groups > comp.lang.java.help > #582

Re: Good practice or not to close the file before System.exit(1)?

Show key headers only | View raw

On 4/22/2011 4:56 AM, Merciadri Luca wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> The fact is that when some specific values of variables are
> encountered, the program can't continue. I would have preferred
> throwing an exception, but there is apparently no reason to throw an
> exception because the variables that need to be checked come directly
> from the arguments that the user passed to the JVM:
>
> java myprogram 1 2 3


Doesn't matter, throw an exception.


>
> It it thus not an `internal error' when some values are encountered,
> because they come from the user.


Doesn't matter.  Exceptions are their for you to extend and use for your 
own purposes.  They are not limited to a few internal errors but cover 
all types of exceptional processing.


>
> As a result, I don't throw an exception when some specific values of
> the variables are encountered, but I make a System.err.println("Some
> text") followed by a System.exit(1).


Compare with the Apache CLI package, which does the grunt work of 
reading command line arguments for you:

parse

CommandLine parse(Options options, String[] arguments)
                   throws ParseException

They make their own exception, ParseException, and throw it when they 
encounter unknown flags or other errors.  The expectation is that you 
will catch ParseException, print out a usage line, preform any other 
final processing (close files), and then exit with status.

<http://commons.apache.org/cli/usage.html>

In your particular case, yes you could almost certainly avoid opening 
the files first.  However in general this follows the same pattern that 
all other exceptional processing follows:  throw an error when you have 
a problem, let the high level code catch it and deal with the results.

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

Thread

Good practice or not to close the file before System.exit(1)? Merciadri Luca <Luca.Merciadri@student.ulg.ac.be> - 2011-04-22 00:13 +0200
  Re: Good practice or not to close the file before System.exit(1)? rossum <rossum48@coldmail.com> - 2011-04-22 00:11 +0100
    Re: Good practice or not to close the file before System.exit(1)? rossum <rossum48@coldmail.com> - 2011-04-22 12:39 +0100
      Re: Good practice or not to close the file before System.exit(1)? Patricia Shanahan <pats@acm.org> - 2011-04-22 05:09 -0700
        Re: Good practice or not to close the file before System.exit(1)? Lew <noone@lewscanon.com> - 2011-04-22 09:39 -0400
          Re: Good practice or not to close the file before System.exit(1)? Merciadri Luca <Luca.Merciadri@student.ulg.ac.be> - 2011-04-23 13:20 +0200
    Re: Good practice or not to close the file before System.exit(1)? Merciadri Luca <Luca.Merciadri@student.ulg.ac.be> - 2011-04-22 16:37 +0200
  Re: Good practice or not to close the file before System.exit(1)? Patricia Shanahan <pats@acm.org> - 2011-04-22 04:55 -0700
  Re: Good practice or not to close the file before System.exit(1)? Merciadri Luca <Luca.Merciadri@student.ulg.ac.be> - 2011-04-22 13:56 +0200
    Re: Good practice or not to close the file before System.exit(1)? Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-04-22 09:36 -0300
    Re: Good practice or not to close the file before System.exit(1)? markspace <-@.> - 2011-04-22 08:20 -0700
      Re: Good practice or not to close the file before System.exit(1)? Patricia Shanahan <pats@acm.org> - 2011-04-22 09:04 -0700
        Re: Good practice or not to close the file before System.exit(1)? markspace <-@.> - 2011-04-22 15:24 -0700
          Re: Good practice or not to close the file before System.exit(1)? markspace <-@.> - 2011-04-22 18:11 -0700
            Re: Good practice or not to close the file before System.exit(1)? markspace <-@.> - 2011-04-23 08:25 -0700
      Re: Good practice or not to close the file before System.exit(1)? Merciadri Luca <Luca.Merciadri@student.ulg.ac.be> - 2011-04-22 18:55 +0200
        Re: Good practice or not to close the file before System.exit(1)? Lew <noone@lewscanon.com> - 2011-04-22 13:40 -0400
        Re: Good practice or not to close the file before System.exit(1)? Patricia Shanahan <pats@acm.org> - 2011-04-22 10:55 -0700
          Re: Good practice or not to close the file before System.exit(1)? Merciadri Luca <Luca.Merciadri@student.ulg.ac.be> - 2011-04-22 22:58 +0200
            Re: Good practice or not to close the file before System.exit(1)? Merciadri Luca <Luca.Merciadri@student.ulg.ac.be> - 2011-04-22 23:09 +0200
              Re: Good practice or not to close the file before System.exit(1)? Patricia Shanahan <pats@acm.org> - 2011-04-22 14:30 -0700
                Re: Good practice or not to close the file before System.exit(1)? markspace <-@.> - 2011-04-22 15:38 -0700
                Re: Good practice or not to close the file before System.exit(1)? Patricia Shanahan <pats@acm.org> - 2011-04-22 17:00 -0700
                Re: Good practice or not to close the file before System.exit(1)? Lew <noone@lewscanon.com> - 2011-04-22 22:10 -0400
                Re: Good practice or not to close the file before System.exit(1)? Patricia Shanahan <pats@acm.org> - 2011-04-22 19:46 -0700
                Re: Good practice or not to close the file before System.exit(1)? Lew <noone@lewscanon.com> - 2011-04-23 09:54 -0400
  Re: Good practice or not to close the file before System.exit(1)? Roedy Green <see_website@mindprod.com.invalid> - 2011-04-22 12:45 -0700
    Re: Good practice or not to close the file before System.exit(1)? Merciadri Luca <Luca.Merciadri@student.ulg.ac.be> - 2011-04-22 23:20 +0200

csiph-web