SAX RFD: ModSAX Predefined Features

James Clark jjc at
Mon Mar 8 02:04:22 GMT 1999

David Megginson wrote:

> The parser may throw an exception for either of two reasons:
> 1. it cannot validation; or
> 2. it does not recognise the property.
> If the application wants to determine which of the two is the case,
> then it can try the following:
>   try {
>     parser.setFeature("", false);
>   } catch (SAXNotSupportedException e) {
>     // ...
>   }
> If the parser throws an exception again, then it does not recognise
> the property name (in other words, it may or may not perform
> validation, and the application has no way to tell); if the parser
> does not throw and exception, then it simply does not support
> validation.

Wouldn't it be simpler to throw different type of exception in these two
cases?  You could have a SAXNotRecognizedException that extends
SAXNotSupportedException, and say that parsers should throw
SAXNotRecognizedException when the reason they don't support a feature
is that they do not recognize the feature.


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