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where do exceptions need to be declared?

ok I'm writing an app and I'm trying to follow some guidelines and only throw new exceptions that have been derived from the exception class.

the question though.. is should I create a new file for all new exception classes that I make? if I plan on using an exception in more than one dll.. where does that normally go?

do I create a dll of nothing but exceptions that can be thrown from anywhere?
1 Solution
Hi jayrod

Here are some guidelines that may help you

1) You do not need to create a new file for each new exception.
You can define the exception in the same file that is thrown, in a separate file, or all exceptions in the same file.

Personally I would define the exception in a file that represents the context where the exception arises.

2) If you want to use an exception in more than one dll, I would suggest the following....

If the exception you're talking about is a general use exception, such as InvalidInputException or something like that, I would put it in a separate dll. Somewhere where you would put some classes of general use. Keep in mind that you do not need to put just exceptions there, place all general use code  you have.
After that you would need to make your dlls using that exception depend on this general-use dll.

Finally I would suggest that you derive exceptions not from the Exception class but from ApplicationException.


ApplicationException is thrown by a user program, not by the common language runtime. If you are designing an application that needs to create its own exceptions, derive from the ApplicationException class. ApplicationException extends Exception, but does not add new functionality. This exception is provided as means to differentiate between exceptions defined by applications versus exceptions defined by the system.

Hope this helps

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