Re: On exceptions

From:

Lew <lew@nospam.lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Fri, 25 May 2007 09:08:08 -0400

Message-ID:

<jbOdnXT4N_QkQsvbnZ2dnUVZ_rKvnZ2d@comcast.com>

Christian wrote:

dvdsum schrieb:

Hello,

I have a question. In language like C, to understand the exact error
occurred in a program, we make a comparison between the code returned
by a function and a constant defined in the same library.

In java we have exceptions, which are too generic and are associated
with different errors. For example:

PipedInputStream read method throws an IOException if input is not
connected with an output stream, or pipe is closed or other IO errors.
Now, form the block catch(IOException e) how can I know the exact
error?

you can use the exceptions .toString() method to get some more detailed
info..

also printing the statcktrace will help you to determine what really
happended..

Also you can use getCause(). Log these data at various levels, e.g.,

catch( IOException exc )
{
   String msg = "IOException during PipedInputStream.read(). "+ exc;
   logger.error( msg );
   if ( exc.getCause() != null )
   {
    logger.info( "Cause: "+ exc.getCause() );
   }
   for ( StackTraceElement elem : exc.getStackTrace() )
   {
    logger.debug( elem );
   }
   return Values.FAILURE;
}

--
Lew