Java
The article Tired of Null Pointer Exceptions? Consider Using Java SE 8's Optional! by Raoul-Gabriel Urma gives an extensive description about how to use Optional to improve your API and avoid NullPointerExceptions.
Oleg Shelajev wrote an interesting article about the unpredictability of parallel streams. The stream API is one of the major features introduced with Java 8 and it seems to be easy and powerful. But as Oleg describes in his article, it can influence the performance of your application in an unpredictable way.
Java EE
Maven archetypes are a quick and easy way to setup a Maven project and immediately start with the implementation. But so far there was no archetype to create a Java EE 7 project with Arquillian dependencies and profiles (at least as far as I know...). If you have used Arquillian to test your application, you know that setting up the profiles for different application servers is always some annoying (copy & paste) work.This has changed since Arun Gupta introduced a Maven Archetype for Java EE 7 projects with Arquillian profiles on his blog. The archetype provides Java EE 7 dependencies and creates a managed and a remote profile for Wildfly and GlassFish.