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.
It's important to remember that initialization of instance variables is not the same as executing a constructor. In the case you gave, the results would probably be the same either way. However, consider what would happen if you had multiple constructors:
In such a case, it would probably be better to initialize the member xx outside of the constructors because, otherwise, you're simply creating extra code. Corey
Just as a side-note, there a many intricacies to initializing a class. Take a look at the JLS, §12.4 Initialization of Classes and Interfaces or do a search in the Programmer Certification Forum to get all sorts of juicy details. Hope that helps, Corey