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Java

Posted by Melody derouge
Melody derouge
131 Points

equals() and hashCode() overriding tips

Hi everyone

i'm learning how to work with HashSets right now , and after some research i've found out that i should override equals() and hashCode() , but i'm a bit confused because i've seen so many examples and i can't find a pattern that makes sense to me . Can someone please throughly explain to me how and why (because i don't quite understand why isn't it enough to override equals()) i should override them and if there is some tips that i should keep in mind while doing that? I would appreciate any help :)

Simon Coates
Simon Coates
28,695 Points

I think hashing relates to assignment of different values into buckets (discussed at http://www.jitendrazaa.com/blog/java/what-is-the-need-to-override-hashcode-and-equals-method/ ). The hashCode method's documentation at https://docs.oracle.com/javase/7/docs/api/java/lang/Object.html states a general contract for hashcode. Stackoverflow has a suggestion on how to write the thing at http://stackoverflow.com/questions/113511/best-implementation-for-hashcode-method .