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Posted to issues@commons.apache.org by "Feeling Groovy (JIRA)" <ji...@apache.org> on 2012/10/13 14:28:03 UTC
[jira] [Updated] (IO-340) 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 )
[ https://issues.apache.org/jira/browse/IO-340?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Feeling Groovy updated IO-340:
------------------------------
Comment: was deleted
(was: The bug is known:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5003595
Because of file system complications, it cannot be fixed and the user if left to sort it out.
However, when I use FileUtils.contentsEquals(filea,fileb) it does file.exists internally as preliminary comparisons.
.. and then it produces erratic behaviour.
Took me a while to figure our why my backups were not working and it was this bug. There are lots of other links on the web about this same bug:
http://stackoverflow.com/questions/3833127/alternative-to-file-exists-in-java
http://www.coderanch.com/t/369040/java/java/java-io-File-exists-bug
Cheers,
Wilf)
> 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: Feeling Groovy
> 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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