Why Create Custom Exceptions? [closed]

Question

Why do we need to create custom exceptions in .NET?

Answer 1

Specific customs exceptions allow you to segregate different error types for your catch statements. The common construct for exception handling is this:

try {} catch (Exception ex) {} 

This catches all exceptions regardless of type. However, if you have custom exceptions, you can have separate handlers for each type:

try {} catch (CustomException1 ex1) {     //handle CustomException1 type errors here } catch (CustomException2 ex2) {     //handle CustomException2 type errors here } catch (Exception ex) {     //handle all other types of exceptions here } 

Ergo, specific exceptions allow you a finer level of control over your exception handling. This benefit is shared not only by custom exceptions, but all other exception types in the .NET system libraries as well.

Answer 2

I did a lengthy blog post on this subject recently:

http://blogs.msdn.com/jaredpar/archive/2008/10/20/custom-exceptions-when-should-you-create-them.aspx

The crux of it comes down to: Only create a custom exception if one of the following are true

1. You actually expect someone to handle it.
2. You want to log information about a particular error