Java - TreeSet and hashCode() -


i have quick question treeset collections , hashcode methods. have treeset , i'm adding objects it, before add object, check see if exists in treeset using contains method.

i have 2 distinct objects, each of produce distinct hashcode using implementation of hashcode method, example below:

public int hashcode() {     int hash = 7;     hash = hash * 31 + anattribute.hashcode();     hash = hash * 31 + anotherattribute.hashcode();     hash = hash * 31 + yetanotherattribute.hashcode();     return hash; }

the hashcodes particular run are: 76126352 , 76126353 (the objects differ 1 digit in 1 attribute).

the contains method returning true these objects, though hashcodes different. ideas why? confusing , appreciated.

treeset not use hashcode @ all. uses either compareto or comparator passed constructor. used methods contains find objects in set.

so answer question compareto method or comparator defined 2 objects in question considered equal.

from javadocs:

a treeset instance performs element comparisons using compareto (or compare) method, 2 elements deemed equal method are, standpoint of set, equal.


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