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copied!<blockquote> <p>I need to keep an unique ID for each object that I'm using, that's why I decided to use the IdentityHashCode, as far as I understand, this value is the same through the compilation.</p> </blockquote> <p>No. It's got nothing to do with compilation, and it's <em>not</em> guaranteed to be unique.</p> <p>It's not clear what you're trying to do, but you simply shouldn't regard hash codes as unique - they're not guaranteed to be.</p> <p>The <code>Object.hashCode</code> documentation specifies:</p> <blockquote> <p>As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects.</p> </blockquote> <p>That's not the same thing as guaranteeing it though.</p> <p>You're <em>also</em> being confused by the result of calling <code>toString()</code> - I suspect your class actually overrides <code>hashCode()</code>, and <code>Object.toString()</code> calls the potentially-overridden <code>hashCode()</code> method rather than using the identity hash code:</p> <blockquote> <p>The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:</p> <pre><code>getClass().getName() + '@' + Integer.toHexString(hashCode()) </code></pre> </blockquote> <p>If you call <code>obj.hashCode()</code> you'll see the same value that's shown by <code>toString</code>.</p>

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