CWE-581 - Object Model Violation: Just One of Equals and Hashcode Defined
- Abstraction:Variant
- Structure:Simple
- Status:Draft
- Release Date:2006-12-15
- Latest Modification Date:2024-02-29
Weakness Name
Object Model Violation: Just One of Equals and Hashcode Defined
Description
The product does not maintain equal hashcodes for equal objects.
Java objects are expected to obey a number of invariants related to equality. One of these invariants is that equal objects must have equal hashcodes. In other words, if a.equals(b) == true then a.hashCode() == b.hashCode().
Common Consequences
Scope: Integrity, Other
Impact: Other
Notes: If this invariant is not upheld, it is likely to cause trouble if objects of this class are stored in a collection. If the objects of the class in question are used as a key in a Hashtable or if they are inserted into a Map or Set, it is critical that equal objects have equal hashcodes.
