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https://issues.apache.org/jira/browse/IO-340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13428589#comment-13428589
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Sebb commented on IO-340:
-------------------------
Strange that file.exists() should not cause a handle refresh whereas it appears
file.length() does.
But it's not a full solution as file.length() can be zero for a file that does
exist.
Perhaps it works for you because none of your files are empty?
Might be better to check for lastModified != 0, as that would potentially work
with empty files too.
Nevertheless, all code should still allow for the fact that files can
appear/disappear between the check and the next file operation. Potentially
even on local storage if a hardware fault occurs.
> The use of file.exists() is failure prone. Where file.exists() is checked, it
> should be replaced with the following dual check: exists = ( file.exists()
> || file.length()>0 )
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: IO-340
> URL: https://issues.apache.org/jira/browse/IO-340
> Project: Commons IO
> Issue Type: Bug
> Components: Utilities
> Affects Versions: 2.5, 3.x
> Environment: All
> Reporter: Wilf Middleton
> Labels: File, exists, false
> Fix For: 2.5, 3.x
>
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> The use of file.exists() is failure prone. In many cases the jvm can report
> that a file does not exist even when it does. This is due to the caching in
> the operating system.
> Since file.exists() is prone to report false values, a second check can and
> should be made to file.length()>0.
> Where file.exists() is checked, it should be replaced with the following dual
> check:
> A file more reliably exists if: file.exists() || file.length()>0
> Then if the file does not exist, file.length will be 0.
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