<p> This class overrides <code>equals(Object)</code>, but does not override <code>hashCode()</code>, and inherits the implementation of <code>hashCode()</code> from <code>java.lang.Object</code> (which returns the identity hash code, an arbitrary value assigned to the object by the VM).&nbsp; Therefore, the class is very likely to violate the invariant that equal objects must have equal hashcodes.</p> <p>If you don't think instances of this class will ever be inserted into a HashMap/HashTable, the recommended <code>hashCode</code> implementation to use is:</p> <pre><code>public int hashCode() { assert false : "hashCode not designed"; return 42; // any arbitrary constant will do } </code></pre>

<p> A class defines an equals(Object) method but not a hashCode() method, and thus doesn't fulfill the requirement that equal objects have equal hashCodes. An instance of this class is used in a hash data structure, making the need to fix this problem of highest importance.