Sax Exception conversion to user defined exception not working.

[Mohammed Ajmal]

Hi,

I have written a parser in java using SAXParser.
Also, schema validation is done. So when I give a incorrect xml it throws SAXException and I am able to catch the same. But on catching it I am conveting it to userDefined exception and throwing the same to client(java application), but on catching the same in client it is getting converted to null pointer exception and i have to put a catch( Exception ex) block to catch it, it is not getting catched in userdefined catch block.

code snippet
----------------------------
parser:

method parseInput (...) throws parseException

catch(SAXException sx)
{
throw new parseException( sx.getMessage());
}

client:

try
{
parseInput()
}
catch( parseException pe )
{
...
}
catch ( Exception e)
{
// Here it is getting caught.
System.out.println(" prints exception message as " + e.getMessage())) as NULL.
}
}

-- End -----------------------------------

Could some one throw pointers on the same.

Your help is highly appreciated and thanks for the same.

[Stefan Wagner]

looks as if 'sx.getMessage()' returns null.

s = sx.getMessage ();
if (s == null) s = "empty Sax-Exception-message";
throw new parseException (s);

[Layne Lund]

Rather than just taking the message from the "causing exception". You should use the "exception chaining paradigm" by writing an constructor in your custom exception class that takes an Exception parameter as well as the String message. In JDK 1.4 and beyond, this is already supported in the base Exception class, so it is farily easy to implement. If you use this paradigm, you would then be able to do something like this:

throw new parseException("a meaningful message", sx);

HTH

Layne
[ March 19, 2005: Message edited by: Layne Lund ]