Christopher Molin created COLLECTIONS-872:
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Summary: MultiKeyMap: Key-objects are stored as reference, making
it possible to modify the Map externally
Key: COLLECTIONS-872
URL: https://issues.apache.org/jira/browse/COLLECTIONS-872
Project: Commons Collections
Issue Type: Bug
Components: Map
Affects Versions: 4.5.0-M2, 4.5.0-M1, 4.4, 4.3, 4.2, 4.1, 4.0, 4.0-alpha1,
3.2.2, 3.2.1, 3.2, 3.1, 3.0, 2.1.1, 2.1, 2.0
Reporter: Christopher Molin
When using MultiKeyMap, the keys are stored as-is (as references).
This leads to the following problem:
# Create a MultiKeyMap, with key(s) of a type (class/record) which has some
fields.
# Use multiKeyMap.put(T... keys, R value), to create an entry in the Map, to
map the keys to a value
# Use multiKeyMap.get(T... keys), to verify that the mapping exists and
returns the expected value.
# Modify/alter any of the objects used as a key. It is enough to change the
value of any member field of any of the objects.
# Use multiKeyMap.get(T... keys) again, however, now there is no mapping for
these keys!
# Use multiKeyMap.get(T... keys) with the new modified/altered objects, and it
will return the expected value
This is potentially a major issue - especially for those unaware of this
behavior!
This is a problem since the introduction in v1.17
Potential Solution:
Calculate the Hash of the keys, and use those as keys. This way, would not be
subject to external modification.
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