Is it a good practice to calculate and override hashCode once for ever
<p>I work with the OpenSource OODB <a href="http://community.versant.com/Downloads.aspx" rel="nofollow">db4o</a> and my serialized classes inherit from a common abstract.class which have two fields :</p>

<pre><code>. . .
private final Long timeCreate = (System.currentTimeMillis() &lt;&lt; 20) + (System.nanoTime() &amp; 0xfffff);
private final int hashCode = timeCreate.hashCode();
. . . 
@Override
public final int hashCode() {
    return hashCode;
}
. . .
</code></pre>

<p>Is it a good practice to so?</p>

<p>The benchmarks I've tried give faster responses, but is a pitfall nested some where?</p>
