Following his PS4 7.5X Jailbreak 6.72, 7.02 & 7.50-7.55 Online Hosts and PS4 Offline Account Activator Reimplementation, developer @sleirsgoevy (Twitter) recently updated his Github repository with Jamvm PS4 which is a work-in-progress (WIP) port of the open-source JamVM (Java Virtual Machine) free implementation of Java 1.6 runtime for the PlayStation 4 Scene to enjoy! 
Download: jamvm-ps4-master.zip / GIT
This comes proceeding early PS4 Blu-ray Java Homebrew, a PS4 BD-J FAQ, a Blu-ray Disc Java Game Preview, the Ukko's Journey Blu-Play Homebrew Game release, another Blu-Play Game Development update, The UFO Game! Blu-Play Game release and a Blu-Play DOOM I Game C / C++ to BD-J Port.
From the README.md, to quote: jamvm-ps4
This is a (possibly incomplete) port of JamVM, a free implementation of Java 1.6 runtime, to the PS4. It successfully runs a "Hello, world!" from normal classpath (not bootclasspath).
A port of some Java-based game would be great, but it's unlikely to happen until GNM is reversed.
Building
Dependencies:
To build, run bash build.sh. This will build JamVM and all dependencies, and produce jamvm.o in the root directory. This object can then be linked into an application.
Cheers to Jhonson94296749 for the heads-up on this news via Twitter earlier on!
Download: jamvm-ps4-master.zip / GIT
This comes proceeding early PS4 Blu-ray Java Homebrew, a PS4 BD-J FAQ, a Blu-ray Disc Java Game Preview, the Ukko's Journey Blu-Play Homebrew Game release, another Blu-Play Game Development update, The UFO Game! Blu-Play Game release and a Blu-Play DOOM I Game C / C++ to BD-J Port.
From the README.md, to quote: jamvm-ps4
This is a (possibly incomplete) port of JamVM, a free implementation of Java 1.6 runtime, to the PS4. It successfully runs a "Hello, world!" from normal classpath (not bootclasspath).
A port of some Java-based game would be great, but it's unlikely to happen until GNM is reversed.
Building
Dependencies:
- OpenOrbis PS4 toolchain
- JDK
- zlib
- m4
- libtool
- autoconf
- automake
- zip
Code:
wget https://gmplib.org/download/gmp/gmp-6.2.0.tar.lz && tar -xvf gmp-6.2.0.tar.lz
wget https://zlib.net/zlib-1.2.11.tar.gz && tar -xvf zlib-1.2.11.tar.gz
wget https://ftp.gnu.org/gnu/classpath/classpath-0.99.tar.gz && tar -xvf classpath-0.99.tar.gz
git clone https://github.com/xranby/jamvmCheers to Jhonson94296749 for the heads-up on this news via Twitter earlier on!
