Why would I care about IOExceptions when a file is closed?

Question

I've see this sort of thing in Java code quite often...

try
{
    fileStream.close();
}
catch (IOException ioe)
{
    /* Ignore. We do not care. */
}

Is this reasonable, or cavalier?

When would I care that closing a file failed? What are the implications of ignoring this exception?

Answer 1

I would at the very least log the exception.

I've seen it happen occasionally, if the attempt to close the file fails due to it not being able to flush the data. If you just swallow the exception, then you've lost data without realizing it.

Ideally, you should probably swallow the exception if you're already in the context of another exception (i.e. you're in a finally block, but due to another exception rather than having completed the try block) but throw it if your operation is otherwise successful. Unfortunately that's somewhat ugly to sort out :(

But yes, you should at least log it.