Why use customized / particular exceptions instead java.lang.Exception

Question

Hi,
Do any of you guys know where can I find a theorical statement / explanation about why use particular / customized exceptions instead java.lang.Exception? I am aware that it consumes more resources and becomes a heavier object, as well as the clearness when coding and all that stuff; however, my boss wants to see a tech document where all this is clearly stated. Any resource over there?
Regards

Answer 1

It is better to throw specific--or at least module- or
package-specific--excpetions, rather than Exception,
because then the caller knows what to expect. However,
if you declare "throws Exception", the caller can
still catch IOException, SQLException, etc.,
separately. He'll just have to be a really good
guesser as to which ones he should catch.True.
Also, there's no point in declaring "throws
NullPointerException." Any method can throw it without
declaring it. If you generate your own NPE (or other
unchecked exception) inside the method, then you
should document it in the javadoc comments, but you
don't need to put it in the throws clause. It doesn't
do any harm, but it's redundant and cluttersome.It was an example and I wasn't feeling too creative....excuse me. ;-) But yeah, I've never thrown NPE ever.
I'm assuming overhead caused by extending classes.At
the worst, it would be miniscule, or so I wouldthink.
What overhead is created by extending classes?Hmm, I was under the impression that a class the extended another class, inherited all of the other classes data (variables, etc.). Hence, you get something like this:
SuperClass1 + SubClass1 + SubClassOfSubcCass1 = Memory usuage for SubClassOfSubClass1.
Since adding postivie number will always end up increasing data, SubClassOfSubClass1 will use more dtat than SuperClass1.
Am I wrong?