Can we get compiler warnings for empty catch blocks?

[David Alayachew]

Thanks Manu. I do have a few ways around this, but I like your idea the
best.

Still, I think this problem is significant enough and common enough that we
are justified by putting it in the compiler warning list.


On Fri, Jun 20, 2025, 9:50 PM Manu Sridharan <manu at sridharan.net> wrote:

> Hi David, FYI Error Prone has a check for this:
>
> https://errorprone.info/bugpattern/EmptyCatch
>
> Best,
> Manu
>
> On Jun 21, 2025 at 08:18:25, David Alayachew <davidalayachew at gmail.com>
> wrote:
>
>> Oh I agree they serve a purpose. But I think the default is on the wrong
>> side. I think it should warn by default, and let me supress warnings if it
>> indeed is intentional. That's why I am suggesting this compiler warning --
>> to allow me to opt-in to switching the default.
>>
>> I was not the one who wrote the empty catches. But I am finding that each
>> one was a mistake of some sort. For almost every one, we could have logged
>> it at least. Leaving them empty was wrong in almost every single instance I
>> found.
>>
>> And the folks who committed most of these were intern-level devs -- devs
>> who don't know the difference between static and instance.
>>
>> Now that I am playing clean up, I wanted to make it easier to just bring
>> all these (likely) problematic empty catch blocks to the surface, then put
>> a SuppressWarnings on each one that actually SHOULD be empty (yet to find
>> one, but I concede that is possible).
>>
>> On Fri, Jun 20, 2025, 7:11 PM Chen Liang <chen.l.liang at oracle.com> wrote:
>>
>>> Empty catch blocks serve a purpose: They aim to catch the type of
>>> exception from the try block, and continue execution from immediately after
>>> the try-catch statement. As Brian Goetz often says, let's first look at the
>>> problem instead of a solution. What prompted you to write those empty catch
>>> blocks at first?
>>> ------------------------------
>>> *From:* compiler-dev <compiler-dev-retn at openjdk.org> on behalf of David
>>> Alayachew <davidalayachew at gmail.com>
>>> *Sent:* Friday, June 20, 2025 6:00 PM
>>> *To:* compiler-dev <compiler-dev at openjdk.org>
>>> *Subject:* Can we get compiler warnings for empty catch blocks?
>>>
>>> I got burned pretty bad today because of a large number of empty catch
>>> blocks.
>>>
>>> If a compiler warning is not feasible or not a good idea, that's fine.
>>>
>>> But please let me know -- whether yes, no, or otherwise.
>>>
>>
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