Why again am I not using JDK 1.6?

Why in the world am I still using jdk 1.5? It's almost 4 years old. Yesterday it just kind of hit me and I said to myself, "James, why not start using jdk 1.6 or java 6?". Is there anything technically preventing jdk 1.5 users from using jdk 1.6? Back in the day, weblogic 6.1 only worked with jdk 1.3 and when I wanted to start using jdk 1.4 it just wouldn't work. So for some reason I still had that same mindset.

So I started to do a little research and what I found was pleasantly surprising and I immediately downloaded the latest version of java 6 and started using it (verdict still out on that but so far so good). JBoss 4.2.1 seems to start just fine with java 6.

So what exactly did I find? First, straight from the java 6 home page is the answer to the question: Q: How is Java SE 6 different from the previous version (J2SE 5.0): what are the improved and updated areas, such as functionality, security, performance?

...the release delivers dramatic out-of-the-box benefits without any coding changes or even a re-compile necessary. Simply running existing Java applications on this latest release is all that is needed.

Now my interests are peaked. So how come I haven't heard this yet. Perhaps I was just content being able to upgrade from 1.4 to 1.5.

I think this article by Rick Ross on javalobby has some great points. Here are the ones that interested me:

• Java 6 incorporates over 300 bug fixes
• Java 6 features general performance improvements while preserving compatibility with older versions
• In many cases you may find that your applications run as fast or faster under Java 6 as they would if you spent significant effort tuning heap, thread and garbage collection parameters under Java 5.

That last point hits me right at home since we recently went through "significant effort tuning heap, thread, and gc params."

So what about performance? This article is in an depth analysis of the performance improvements. The summary is it's faster.

So like mentioned above I downloaded java 6 update 6. Jboss 4.2.1 started just fine. Today I plan on building our EAR using maven 2.0.9 and deploying it to see if there are any issues. See the official compatibility page here. Specifically it states "Java SE 6 is upwards binary-compatible with J2SE 5.0 except for the incompatibilities listed below. Except for the noted incompatibilities, class files built with version 5.0 compilers will run correctly in JDK 6."