What does this mean about returning a java immutable result?
<p>"Return an immutable interface to the original data. You can then change fields in the object, but the caller cannot unless he cheats by casting. You expose only the methods you want the user to have. Doing the same with classes is trickier since a subclass must expose everything its superclass does" </p>

<p>What does he mean you can cheat, and why is it tricky with subclasses ? </p>

<p>source: <a href="http://mindprod.com/jgloss/immutable.html" rel="nofollow">http://mindprod.com/jgloss/immutable.html</a></p>
