J2EE

Hi,
Being a Java J2EE developer for more than 3 years, what I understood from my experience is that, there are still wider/ larger scope for these technologies.
If you are pretty good in the most basic concepts of Java (abstraction, polymorphism, inheritance, naming conventions etc. ) you would find it easier to learn and grasp other technologies, which is an added advantage for Java developers.
However, once you are inside an organisation as a Java developer, you would find too many Java resources surrounding you ( which is a bitter truth obviously :) ). So, to stand out of the crowd, it would be always helpful to learn or to to get into project works on Java frameworks such as Structs, Spring, Hibernate, ATG etc.
Also, UI look and feel for web based applications are given predominant considerations nowadays. So don't ever loose a chance where you are getting chances to closely work with UI frameworks.
I was telling these based out of my short experience till date in IT field. Please be updated and be in pace with evolving industry, keeping in mind the fact that ' Change is inevitable' :)
All the best.

For a Java developer, having a strong understanding of Object-Oriented Programming is a must.
Master the core APIs- It doesn't matter how strong you are in terms of theoretical knowledge if you don't know the language constructs and core APIs.
Keep coding- Things look simpler when talking about them theoretically. We can give a solution to a problem very easy in theory. But we can realize the depth of the problem when we start implementing our approach. You will come to know the language limitations, or design best practices while coding. So keep coding.
Subscribe to forums -When starting to work on a new technology the best and first thing to do is subscribe to the relevant technology forums. Whatever the issue you are facing, someone else in the world might have already faced it earlier and might have found the solution. And it would be really really great if you can answer the questions asked by other forum users.
Read open source frameworks source code- A good developer will learn how to use a framework. But if you want to be an outstanding developer you should study the source code of various successful, popular frameworks where you can see the internal working mechanism of the framework and lot of best practices. It will help a lot in using the frameworks in a very effective way.
Know the technology trends- In the open source software development technology trends keep on changing.
Know different development methodologies- Nowadays choosing the development methodology depends on the client. Some clients prefer Agile and some clients are happy with waterfall model. So having an idea of various methodologies would be great.
J2EE would be a better choice as its an extended version. So, definitely opt for that.