Checked exceptions are controversial mostly because a lot of the core APIs use them in places where it's pointless to check, like IOException.
Using them correctly can be great tho.
Using them correctly can be great tho.
Can you explain why this is pointless? In my mind, this being a checked exception would hopefully be a hint that I should think about this failure-case and make an explicit decision whether to handle it or not. Network connection failed? Maybe I retry. Maybe I store that data somewhere else as a fall back. Isn't this similar to Go programmers needing to check if err is not nil?
As soon as you consider retrying a network failure, you immediately need to start thinking about distributed systems failures, idempotency, and all that good stuff.
As soon as you start thinking about the above, it becomes immediately obvious that low-level calls should not be able to decide to re-run themselves.
I appreciate that there is a _ton_ of different experiences out there when it comes to solving problems, but I _have_ encountered exactly the case I was describing, which is what led me to my original question. Isn't the fact that it was a checked exception that led you to "consider retrying a network failure, you immediately need to start thinking about distributed systems failures, idempotency, and all that good stuff" worth it as opposed to an unchecked exception you may not realize is being thrown?
try {
...
} finally() {
...
}
Occasionally though I have built something really sensitive, like an authentication filter for a web site which has at least 5 ways to log in and in that I have a hierarchy of exceptions and use checked exceptions heavily to document all the ways things can go wrong and felt like "the type system really has my back here" but that is like 5% of the Java I write.
That's a code style and code review issue; each project has so set standards regarding how errors are dealt with and enforce them throughput the codebase.
But from a quality standpoint there are three concerns:
(1) Do you actually do the code review, do you actually enforce the style?
I worked on a Scala project where the dev manager thought it was preferable to handle errors with monads and would be vociferous about what a great practice that was compared to exceptions and that code review was central to how we do things... but if you looked at the code most of the time errors just got dropped silently and that was the same for many practices that the dev manager told me were doing but that we don't. He still posts on LinkedIn complaining about other dev managers who say they do code review but really don't. Practically that code didn't consistently give the right answers and poor error handling was one reason, another was that they never really understood that teardown was just as important as initialization.
(2) Is your documented practice correct? Is it really doing the right thing?
In a lot of cases there really is a right and wrong way to do things (e.g. uv resolves Python dependencies properly, pip doesn't) but it's less clear in error handling, like sometimes things went wrong and there is no way you can make it right and you can do the best that you can.
The global nature of the problem is vexing. Like an IOException might really be a BackhoeCutAFiberSomewhereInWisconsinException and a segmentation fault is occasionally a YouAskedForAOneAndGotAZeroInsteadException and it's not just academic because, given an exception, you want to answer questions like "Should I retry this operation? How long should I wait before I retry this operation?"
(3) Is this practice something you can sustain? How hard is to do? How much cognitive load does it add and how does it interact with other practices? "Throw up as much as you can", "tear down in finally {}", "otherwise handle local consequences of errors and rethrow" and "really catch errors at the drivers of units of work" is a practice that really works in many languages and is pretty easy to do right, even code that is written without a lot of care will do the right thing or something close by default. I've seen a lot of "no plan for error handling" or "bad plan for error handling"... like I was traumatized by the first C program I saw in a 1984 issue of Byte magazine which was using errno to handle errors which vastly complicated very simple code because the error path was intimately wound with the happy path and in cases like that there tend to be bugs in both of them. When I saw Exceptions in Java I remembered that old C program and thought "I love this!"
There are several valid ways to do this, but it's important that one strategy is agreed upon and abided to, at least in new code. It's important that one srrategy becomes the orthodox one, else there will never be a reckoning about its effectiveness, but instead only people clinging to their own standards on their own turf. Legacy code complicates the picture of course.