Thursday, July 24, 2008

Bonehead Exception Handling

I found this bit of Java exception handling code in a major open source project -
 
try {
....
} catch (ClassNotFoundException e) {
throw new IntegrationException("Rule Set jar is not correctly formed.");
} catch (IOException e) {
throw new IntegrationException("Rule Set jar is not correctly formed.");
};

The specifics of the code in the try block are unimportant, what does matter is how the exceptions thrown by that code are handled. Besides being completely amateurish, the exception handling is wrong in at least three ways.

First it completely loses the original exception. Whatever context the original exception had is just gone. Since Java 1.4 it has been possible to include the root cause of the error. Before Java 1.4 the programmer could at least have appended the original error message.

Second it turns two completely different types of errors in a one type. Great so now I get an error that could have two very different causes and no way to figure out the actual cause.

Third the error message doesn't say anything at all useful. There is absolutely nothing in the error message that helps me understand or fix the problem. What does "not correctly formed" mean and what in the world does being or not being well formed have to do with a ClassNotFoundException or an IOException?

I suppose I should take some solace in the fact that at least it reports an error. But frankly this code is only slightly better than just swallowing the errors.

1 comment:

Joshua Smith said...
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