I notice that a number of Java exception classes differ only in the name of the class and do not add any new functionality. Most exceptions for example just seem to override Exception() or Exception(String message). This goes against the tenets of inheritance ie:- inherit to add new functionality.
What are some good reasons to create a new Exception class?
You can catch exceptions by type, and having an exception of a particular type that is otherwise identical to the base Exception class allows you to be precise in your exception handling.
I would argue that it does add new functionality directly by increasing the specificity of exception handling code.
You add a new exception class when a user of your API might need to catch it conditionally (or, for checked exceptions specify different, specific types in a throws).