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https://issues.apache.org/jira/browse/LANG-1261?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15501212#comment-15501212
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ASF GitHub Bot commented on LANG-1261:
--------------------------------------
Github user asfgit closed the pull request at:
https://github.com/apache/commons-lang/pull/183
> ArrayUtils.contains returns false for instances of subtypes
> -----------------------------------------------------------
>
> Key: LANG-1261
> URL: https://issues.apache.org/jira/browse/LANG-1261
> Project: Commons Lang
> Issue Type: Bug
> Components: lang.*
> Affects Versions: 3.4
> Environment: Android
> Reporter: Homer Jay
> Labels: array, equals
>
> ArrayUtils.contains(Object[] array, Object objectToFind) wrongly returns
> false.
> STEPS TO REPRODUCE
> =========================================================
> -Create a superclass "Parent" and override equals and hashcode based on some
> member id variable.
> -Create a class "Child" extending "Parent". Do not override equals nor
> hashcode.
> -Let "childrens" be an array of type Child[] containing several instances.
> Create an instance of Parent "p" with the same id as childrens[0], such that
> childrens[0].equals(p) returns true and p.equals(childrens[0]) returns true
> as well.
> Because they are equals, ArrayUtils.contains(childrens, p) should return
> true. However it returns false.
> WHERE THE BUG IS LOCATED
> =====================================================
> -Go to ArrayUtils.class, line 1917. In the "indexOf" method implementation,
> before going into calling equals for each element of the input array, there
> is some sort of optimization check to make sure the instance to be found is
> an instance of the array type:
> } else if (array.getClass().getComponentType().isInstance(objectToFind)) {
> That line is wrong. In our case, the array contains elements of type "Child",
> whereas the object to be found is of type "Parent". They are equals according
> to the equals implementation of "Parent", but obviously
> Children.class.isInstance(p) is false.
> EXPECTED BEHAVIOR
> ================================================
> Since the method signature accepts an array of Object[] and an instance of
> Object, it should ignore the classes of the arguments. It should be possible
> to call "ArrayUtils.contains(Child[] children, Parent p)", in fact it should
> be possible to do this with any combination of classes, not only the ones
> assignable from the class hierarchy.
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