Exception Handling and Purpose

[Javini Javono]

Hi,
I'll have to do more reading and review of this topic, both at this web site
and from my books. But, in the interrum, here is my question.
First, the code:

if (localMode) {
//...
} else {//Remote mode.
try {
connectionFactory = ...;
} catch (NotBoundException notBoundException) {
throw new suncertify.system.ServerException
("Obtaining the connectionFactory to the remote server failed.", notBoundException);
} catch (java.net.MalformedURLException malformedUrlException) {
throw new suncertify.system.ServerException
("Obtaining the connectionFactory to the remote server failed.", malformedUrlException);
} catch (RemoteException remoteException) {
throw new suncertify.system.ServerException
("Obtaining the connectionFactory to the remote server failed.", remoteException);
}
}

As an example, you'll see one portion where three exceptions are potentially
caught: notBoundException, malformedUrlException, remoteException.
From my perspective, all I care about as "the running application" is that I
was not able to connect to the "local" or remote server. That is, from the
perspective of "the running application," whether the exception was any one of
these potential three types is not relevant.
Should I also be concerned about the user? That is, should the exception message
offer hints to the user about how to get the application to operate correctly?
Such as:

try {
connectionFactory = ...;
} catch (NotBoundException notBoundException) {
throw new suncertify.system.ServerException
("Obtaining the connectionFactory to the remote server failed.  "
 + "Possible cause or causes:  server is not up and running;  "
 + "client supplied a URL to the wrong address;  "
 + "client is attempting to communicate "
 + "to the remote server from behind a firewall.", notBoundException);
} catch (java.net.MalformedURLException malformedUrlException) {
throw new suncertify.system.ServerException
("Obtaining the connectionFactory to the remote server failed.  "
 + "Possible cause or causes:  the format of the URL address of the "
 + "server was incorrect.", malformedUrlException);
} catch (RemoteException remoteException) {
throw new suncertify.system.ServerException
("Obtaining the connectionFactory to the remote server failed.  "
 + "Possible cause or causes:  an internet connection has not been "
 + "established (i.e., the modem may not be turned on);  "
 + "a remote invocation communication anomoly occurred.", remoteException);
}

Thanks,
Javini Javono

[Mark Spritzler]

Well, yes you do wnat to be concerned about the client. Most importantly that they know something happened. Secondly, wrapping each into a new ApplicationException type exception so that the client only has to catch one exception is very good. Just like you have.
I will say that I am more impressed by the second set of exception handling. It is cool to let the client know some possible remedies. Not necessarily needed for the assignment, but that won't hurt, and if you keep that practice up, very good for the real world.
Mark