thanks a ton. now, i need to spend some hours doing some arrangements in my code but anyway that's for my good ;-)
-navjot singh ----- Original Message ----- From: "Andrew Hill" <[EMAIL PROTECTED]> To: "Struts Users Mailing List" <[EMAIL PROTECTED]> Sent: Thursday, April 03, 2003 5:02 PM Subject: RE: Where to catch/throw Exceptions in Struts Tiered Architecture | Generally, returning null when it should be an error is considered bad | practice. (If null is a valid return value of course thats a different | matter). | In this case you should throw an exception and catch it in the calling class | and branch or throw again appropriately. | You dont want your calling class to have to know about low level details | like specific sql exceptions though, so instead of just letting the sql | exception propogate upwards, you would catch it and throw a different more | abstract exception (probably one you create yourself) up to the caller - the | caller shouldnt have to know the details about your persistence mechanism - | it just needs to know it failed - and sometimes needs to know if the failure | is fatal and any other pertinent info. | The nested excpetion classes should also be able to keep a reference to the | exception they wrap so the stacktrace show all the exceptions in the chain - | useful when debugging. | | btw: If I recall rightly Ted Husted explains this 10 times better in one | tenth the words in his book (struts in action) | | Have a look at these articles: | http://developer.java.sun.com/developer/technicalArticles/Programming/except | ions/ | http://www-106.ibm.com/developerworks/java/library/j-ejb01283.html | http://www.javaworld.com/javatips/jw-javatip91_p.html | | There was another very good one too - but it doesnt seem to be in my | favourites list and I cant seem to find it now. | | | -----Original Message----- | From: Navjot Singh [mailto:[EMAIL PROTECTED] | Sent: Thursday, 3 April 2003 18:53 | To: Struts Users Mailing List; [EMAIL PROTECTED] | Subject: Re: Where to catch/throw Exceptions in Struts Tiered | Architecture | | | hi andrew, | | but surely these long stacktraces are not meant for users ;-) | | what i have got from your statement is something like this | | SQLException | |__DatabaseException | |____ApplicationException | | finally, this ApplicationException is what is being thrown into execute() | call. | | May i am novice, but I still need to be convinced about throwing so many | exceptions in chain | | Can't the stuff be handled in a simple way -- | SAY | a. when you get SQLException, catch and return NULL | b. Calling Class __ifs__ for NULL instead of __catching__ and transfer the | control accordingly. | | Is there something i am ignoring? | | regards | Navjot Singh | | ----- Original Message ----- | From: "Andrew Hill" <[EMAIL PROTECTED]> | To: "Struts Users Mailing List" <[EMAIL PROTECTED]> | Sent: Thursday, April 03, 2003 3:49 PM | Subject: RE: Where to catch/throw Exceptions in Struts Tiered Architecture | | | | I use nested exceptions, and virtually all my methods (and thus layers) | | catch and wrap and throw... | | Makes for some impressively long stacktraces - and is marvellous for | | debugging! :-) | | | | | | -----Original Message----- | | From: Navjot Singh [mailto:[EMAIL PROTECTED] | | Sent: Thursday, 3 April 2003 18:05 | | To: Struts Users List | | Subject: Where to catch/throw Exceptions in Struts Tiered Architecture | | | | | | Hi, | | | | Take a simple case. | | | | Action | | Y | | UserAction -> User -> Database | | | | | V | | user.jsp | | | | Say, Database throws exception. What is best way to handle exception? | | | | 1. Catch in User class and return NULL / some ErrorObject to UserAction | and | | let UserAction decide how to handle it? | | | | 2. Let User class __pass on__ the Exception from Database to UserAction. | | | | 2a. As execute() is already throwing Exception so it will handle ALL so | Set | | <global-exception> handler that can send the user to some nice page? | | 2b. Catch Exception in UserAction and then do some thing ... | | | | Which one do you guys follow in not-so-large scale web applications? | | | | would appreciate any comments. | | -navjot singh | | | | | | | | | | --------------------------------------------------------------------- | | To unsubscribe, e-mail: [EMAIL PROTECTED] | | For additional commands, e-mail: [EMAIL PROTECTED] | | | | | | --------------------------------------------------------------------- | | To unsubscribe, e-mail: [EMAIL PROTECTED] | | For additional commands, e-mail: [EMAIL PROTECTED] | | | | | | | --------------------------------------------------------------------- | To unsubscribe, e-mail: [EMAIL PROTECTED] | For additional commands, e-mail: [EMAIL PROTECTED] | | | --------------------------------------------------------------------- | To unsubscribe, e-mail: [EMAIL PROTECTED] | For additional commands, e-mail: [EMAIL PROTECTED] | | --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
