Homer Jay created LANG-1261:
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Summary: ArrayUtils.contains returns false
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
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
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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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