Changing values in HashSet

Question

I\'ve read this question: Changing the elements in a set changes the \'equals\' semantics

However, I don\'t know how to solve the problem that I can\'t change an ite

Answer 1

When you add testElement to the HashSet, it selects a bucket based on the hash code for testElement. When you ask the HashSet if it contains a TestElement, it computes the hash code of the object that it's looking for and searches only in that bucket.

As your hashCode() is based on non-final field, the hash code can change behind the scenes of the HashSet. Thus completely invalidating the basic assumption of the HashSet.

A correct implementation for the Testclass would have the s1 field as final.