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https://issues.apache.org/jira/browse/IO-808?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17849258#comment-17849258
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Elliotte Rusty Harold commented on IO-808:
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A commons library is not the place to litigate language design questions. Nor
is it a Kotlin library, It's a Java one, so I don't really see what the point
of the stack overflow thread is.
For good developer experience, it's essential that libraries follow the design,
idioms, and patterns of the language they're written for, in this case Java.
Breaking with established and deliberate Java practice on anything — not just
exceptions, but object construction, multithreading, access protection, package
naming, and a hundred other things — is a fatal and all too common flaw among
library maintainers who think they know better than the developers who designed
the language. Maybe they do, but it doesn't matter. Moving away from what
developers have learned to expect in a language leads directly to bugs and
developer pain.
Java libraries either use the Java language and its standard libraries,
including IOException and IllegalArgumentException, the way they were designed
to be used, or the library becomes hard to use and bug prone.
On exceptions in particular, see Section 10 of Effective Java, 3rd edition,
particularly Item 72: Favor the use of standard exceptions.
> FileUtils.moveFile, copyFile and others can throw undocumened
> IllegalArgumentException
> --------------------------------------------------------------------------------------
>
> Key: IO-808
> URL: https://issues.apache.org/jira/browse/IO-808
> Project: Commons IO
> Issue Type: Bug
> Components: Utilities
> Affects Versions: 2.12.0
> Environment: Windows 10
> Reporter: Phil D
> Priority: Major
> Attachments: MakyAckyBreaky.java, TestMoveFileIAE.java
>
>
> Several of the functions in FileUtils are throwing undocumented
> IllegalArgumentException such as moveFile, copyFile and other locations.
> If the desire is to maintain backwards compatibility with the 1.4 branch for
> these functions, then the 2.12 (and 2.13) versions are throwing
> IllegalArgumentException in cases where 1.4 is not. In fact, it seems like
> 1.4 was coded to specifically avoid IllegalArgumentException and throws
> IOExceptions instead.
> There are several different cases where this is possible. In the most basic,
> I've attached TestMoveFileIAE, where this can be reproduced by simple running:
> {code:bash}
> mkdir one
> java -cp <your_classpath> TestMoveFileIAE one two
> Exception in thread "main" java.lang.IllegalArgumentException: Parameter
> 'srcFile' is not a file: one
> at org.apache.commons.io.FileUtils.requireFile(FileUtils.java:2824)
> at org.apache.commons.io.FileUtils.moveFile(FileUtils.java:2395)
> at org.apache.commons.io.FileUtils.moveFile(FileUtils.java:2374)
> at TestMoveFileIAE.main(TestMoveFileIAE.java:13)
> {code}
> In a less likely scenario (which is how I found this issue because this
> happened on a production system); If the srcFile is removed at a certain
> point during moveFile() execution then IllegalArgumentException is throws:
> https://github.com/apache/commons-io/blob/master/src/main/java/org/apache/commons/io/FileUtils.java#L2392
> {code:java}
> 2392 public static void moveFile(final File srcFile, final File destFile,
> final CopyOption... copyOptions) throws IOException {
> 2393 validateMoveParameters(srcFile, destFile); // checks srcFile.exists()
> /// ==== srcFile deleted here!!!
> 2394 requireFile(srcFile, "srcFile"); // checks srcFile.isFile()
> and throws IAE
> 2395 requireAbsent(destFile, "destFile");
> /// ==== srcFile could also be deleted here
> 2396 ... // renameTo or copyFile() which also calls requireCopyFile() and
> requireFile()
> {code}
> This pattern of calling validateMoveParameters() and requireFile() will throw
> IllegalArgumentException every when the srcFile is removed between between
> validateMoveParameters() and requireFile() or requireFileCopy() and
> requireFile()
> Preferably, it would be best if the 2.x versions of FileUtils were backwards
> compatible with 1.x and IllegalArgumentException would not be thrown, but
> IOException (or one of its derivatives) would be. IAE is an unchecked
> exception and can cause unexpected issues.
> I would also suggest that unit tests be created to ensure that these
> functions behave as expected in error conditions.
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