Checked exceptions (original) (raw)

Brian Goetz brian.goetz at oracle.com
Wed Oct 16 17:20:35 UTC 2019

I think there has already been a trend in newer APIs towards using fewer checked exceptions.  It's one of those things that is harder to notice, because no one plants a big red sign saying "I was thinking of using seven kinds of checked exceptions here, but then decided against it."

The question surrounding Double::parseDouble is a different one, though; whether it is better to use the null object pattern to signal failure than using an unchecked exception.  In this case, you can make a reasonable argument that the only way it fails in a way that the caller might care about is if the string didn't represent a double, and the error message that would come with the exception isn't really helpful, so the null object pattern here is an acceptable alternative.

Again, I think you'll find that newer APIs are leaning in this direction too.  And again, I think it's just hard to notice when things are getting incrementally better.

As to curing the existing disease, I suspect the horse has mostly escaped the barn.  (Yes, "fixing" this one issue isn't hard, thought even the bikeshed over naming it would likely dwarf the benefit.  But more importantly, once we start, we've implicitly committed to "fixing" all of them, and the related stream of "You did it here, why don't you do it there" requests is extremely disruptive.  So we tend to look at this sort of change with a broader focus.)

On 10/15/2019 4:15 PM, Thomas May wrote:

So, assuming that checked exceptions are here to stay (right or wrong).

Would it be an option to start adding new APIs to the JDK with either no exceptions or unchecked exceptions? The example that comes to mind is Double#parseDouble. It's annoying to have to deal with NumberFormatException, the API would jive better if instead it returned an Optional. But I realize that isn't possible without a lot of breakage, so what about instead a optionalParseDouble that returns a Optional? Or is this too much effort for the gain?

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