Test a new technology is always a bit tedious and it requires an amount of time. So, this project try to reduce the curve of learning of any new user with EV3Dev-lang-java.

The Prerequisites to use this project are:

• Your MINDSTORMS Brick needs to have installed latest Debian Stretch version. https://www.ev3dev.org/docs/getting-started/
• To increase the EV3 CPU Speed, read the following article: https://lechnology.com/2018/06/overclocking-lego-mindstorms-ev3-part-2/
• Your MINDSTORMS Brick needs to be connected to the same LAN than your laptop. http://www.ev3dev.org/docs/getting-started/#step-5-set-up-a-network-connection

Note: Update the EV3Dev kernel https://www.ev3dev.org/docs/tutorials/upgrading-ev3dev/

sudo apt-get update
sudo apt-get install linux-image-ev3dev-ev3

Once you have all steps done, continue with the next section.

This repository stores a template project about EV3Dev-lang-java. Once you download in your computer the project, open your favourite Java IDE ( Eclipse or IntelliJ) to import this Gradle project. The project includes latest dependencies and an example ready to be deployed on your Robot using the core library from EV3Dev-lang-java.

The project includes some tasks to reduce the time to deploy on your robot.

To start, change the brickHost, brickUser and brickPassword properties in config.gradle. Then, continue to the brick setup.

OpenJDK JRI is preinstalled in the default image, so you only need to install ev3dev-lang-java libraries:

./gradlew getInstaller installJavaLibraries

If you want to use RXTX or OpenCV, you can install them this way:

./gradlew updateAPT installOpenCV installRXTX

On these platforms OpenJDK JRE needs to be installed from Debian repositories too:

./gradlew getInstaller updateAPT installJava installJavaLibraries

If you want to use RXTX or OpenCV, you can again install them this way:

./gradlew updateAPT installOpenCV installRXTX

You can change the project configuration in config.gradle.

• mainClass - Main class of your program.
• brickHost - IP address of your brick.
• brickUser - Username on your brick.
• brickPassword - Password for the brickUser.
• opencv - Whether to include OpenCV libraries.
• rxtx - Whether to include RXTX library.
• userClasspath - List of additional URLs for runtime Java classpath.
• useTime - Can be used to measure the time for which the program runs.
• useBrickman - Should be used when running the program on a brick with a display.
• useSudo - If true, the program is launched under root.
• jvmFlags - Flags for Java Virtual Machine.
  • -Xlog:class+load=info,class+unload=info - Display the debugging info for class loading.
  • -Xshare:on - Enable Class Data Sharing (recommended).
  • -Dcom.sun.management.jmxremote=true -Dcom.sun.management.jmxremote.port=7091 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false - Enable JMX agent.
  • -noverify - Do not verify class bytecode. This can be used to speed up startup time, but it is also a potential big security risk.
  • -XX:TieredStopAtLevel=1 - Do not perform many optimizations. This can be used to speed up startup time.
  • -Djava.security.egd=file:/dev/./urandom - This can be used to speed up random number generation.
• slimJar - Whether to generate a small JAR with external dependencies, or rather to generate a fat jar with embedded dependencies.
• useEmbeddedPaths - Whehter to use classpath and mainclass embedded in JAR or if they should be supplied on the command line.

The project has some tasks developed to interact in 3 areas:

• EV3Dev-lang-java
• EV3Dev
• Installer

You can use the Java IDE to launch the tasks or you can execute them from the terminal:

./gradlew deployRun

• testConnection - Test connection to the brick.
• deploy - Deploy a new build of the program to the brick.
• deployRun - Deploy a new build of the program to the brick and then run it.
• run - Run the program that is currently loaded on the brick.
• undeploy - Remove previously uploaded JAR.
• pkillJava - Kill running Java instances.
• fatJar - Build a fat JAR with all dependencies included inside.

• helpInstall - Print the installer help.
• getInstaller - Download the installer to the brick.
• installJava - Install Java on the brick.
• installOpenCV - Install OpenCV libraries on the brick.
• installRXTX - Install RXTX library on the brick.
• installJavaLibraries - Install EV3Dev-lang-java libraries on the brick.
• javaVersion - Print Java version which is present on the brick.
• updateAPT - Update APT package cache.

• ev3devInfo - Get system summary from ev3dev-sysinfo -m.
• free - Print free memory summary.
• getDebianDistro - Get Debian version information from /etc/os-release.
• ps - Print list of running processes.
• stopBluetooth/restartBluetooth - Stop/restart the Bluetooth service.
• stopBrickman/restartBrickman - Stop/restart the Brickman service.
• stopNmbd/restartNmbd - Stop/restart the NMBD service.
• stopNtp/restartNtp - Stop/restart the NTP service.
• shutdown - Shut down the brick.

The project has the following technical documentation

http://ev3dev-lang-java.github.io/docs/api/latest/index.html

Exist several examples ready to use here:

https://github.com/ev3dev-lang-java/examples

If you have any problem or doubt, use the main projet.

https://github.com/ev3dev-lang-java/ev3dev-lang-java/issues