Java 5, which is tiger release, have many new concepts and features. Here is Java 5 tutorial that will provide you code examples of java 5 along with Java 5 concepts.
Here are tips for programmers for Java memory management in programs. This will help you to avoid outofmemory error at runtime.
Portlets Technology is based on JSR 168. There are many things which are additional to a normal web application. Understand this technology here.
This article discusses different points in EJB Vs Spring comparison in Plain Old Java Object i.e. POJO context.