... just to clarify what the downloads page is talking about ...
4thdwarflord wrote:The explanation on the downloads page is a bit misleading when it says about the JVM. I'm still not sure exactly what that is.
You can use the OpenJDK on any of the Linux distributions available. It's easy to install and already available in the apt-get repository for Raspian. Just use this command on the Pi's console or terminal to install the OpenJDK.
sudo apt-get install openjdk-7-jdk
However, if you want to use Oracle's version of the JDK or JRE, then the current released JDK7 for the Pi (JDK7SE with ARM support) it only supports soft-float (ABI) based distributions of Linux. Thus you can only use this on the older Debian "Wheezy" Linux distribution available on the downloads page. Most users are installing the newer and more actively updated Raspbian Linux distribution available on the downloads page, but this is a hard-float (ABI) based Linux distribution and thus not compatible with Oracle's JDK7 for ARM.
Here are installation instructions on how to install the Oracle JDK7 on a Raspberry Pi using a Debian "Wheezy" (soft-float) distribution:
OK .. one more curve ball .... very recently Oracle announced (http://www.raspberrypi.org/phpBB3/viewt ... 81&t=26110
) an early access development release of the JDK8 for ARM which does support hard-float (ABI) based systems. This JDK8 should be considered experimental since it is not released.
Here are installation instructions on how to install the Oracle JDK8 early access on a Raspberry Pi using a Raspian "Wheezy" distribution:
One last thing to consider ... "Why would I want to run the Oracle JDK versus the OpenJDK" ?
Well, the Oracle JDK includes a JIT compiler that allows your Java program to run much faster compared to the OpenJDK (Zero VM) with no JIT. There are options in the OpenJDK to run using alternate VMs (such as Jamvm, Avian, Cacao) that do support varying levels of JIT compilers and performance enhancements, but I have not yet seen any stats that outperform Oracle's VM.
Here is an article that I published a while back comparing the Oracle JVM and the OpenJDK using Zero VM: http://www.savagehomeautomation.com/pro ... marks.html
Also see this thread for more recent performance testing results with some of the other OpenJDK VMs: http://www.raspberrypi.org/phpBB3/viewt ... 81&t=25418