This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
That exercise looks familiar; please quote Your Source. And please use the code button to preserve indentation and legibility.
When you get to the end of the method, work out which object the e1 reference points to, then work out what all its fields are, and whether they have any references. Write it on a sheet of paper and that ought to explain your problem.