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From Alex Blewitt <>
Subject [Error handling] NullPointer or IllegalArgument?
Date Thu, 14 Aug 2003 08:25:50 GMT
On Thursday, Aug 14, 2003, at 07:57 Europe/London, James Strachan wrote:

> On Thursday, August 14, 2003, at 06:31  am, Aaron Mulder wrote:
>> Maas,
>> egarding this particular patch, I'd prefer that we don't actually
>> add "null" to the list of DeploymentFactories, even if it's passed as 
>> an
>> argument to DeploymentFactoryManager.registerDeploymentFactory().  
>> That's
>> silly, we should just ignore a null.
> Failing fast with silly arguments is a good idea - e.g. throw an 
> IllegalArgumentException or NullPointerException.

I've never liked the idea of a method throwing an NPE when passed a 
null argument. A bunch of the Java data structures do this, and I've 
had pains when they do so.

An NPE (to me) means a coding bug, usually requiring a lot of hard work 
figuring out where it came from and why it exists

An IllegalArgumentException means that a method has been passed a wrong 
value (i.e. value out of range, string in wrong format, null value 
passed when arg was required), and usually has some kind of error 
message associated with it.

Go on, tell me which you'd prefer to see in the logs:

[Exception] NullPointerException

[Exception] IllegalArgumentException: address must not be null


PS Votes for saying 'never throw NPEs in methods; use IAE instead?' in 
the coding standards?

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