Installing leJOS NXJ on OSX

posted 11 years ago

For class, we're supposed to install the LeJOS NXJ SDK. There weren't instructions for macs though, so thought I'd share my steps.

Check You Have Java

First, you need to have java installed. To check if it's installed properly, open a terminal and make sure the following command doesn't come back with a "command not found" message.

$ java && javac

If either one isn't found, you need to look up how to add java to your PATH or install JVM / JRE.

Install LeJOS

Go to the leJOS SourceForge page and download the latest version. Unzip it (if you don't have an unzipping tool, check out The Unarchiver).

Delete the "build" directory. Then move the whole folder to where you keep your sdks. I put mine in /Developer/SDKs. Open up your .profile or .bashrc (where you put environment variables) and point NXJ_HOME to the unpacked folder. 

# ~/.profile

export NXJ_HOME="/Developer/SDKs/leJOS_NXJ_0.9.1beta-3"

Also add the "bin" directory of the sdk to your path variable. Makes sense to do it for all users, so add a new file to paths.d. Set the path to where you put the sdk, plus bin. To find it echo the environment variable. 

$ echo $NXJ_HOME/bin

# /etc/paths.d/nxj

/Developer/SDKs/leJOS_NXJ_0.9.1beta-3/bin

If all went well, nxj should be a command in a fresh terminal window.

$ nxj

Eclipse Plugin

In Eclipse, go to { help > Install New Software... } and "work with" the following url:

http://lejos.sourceforge.net/tools/eclipse/plugin/nxj/

Check the box next to leJOS NXJ Support and click "next >", "next >", agree to the terms & conditions, and "finish". There's some unsigned content. Click "ok". Click "yes" to restart Eclipse.

Manual Upload (Bash)

I don't like IDEs. If you don't either, here is the process to manually compile and upload programs for the NXT brick:

# clean out the old files, ignore error messages

rm classes/*.class > /dev/null 2>&1
rm *.nxj > /dev/null 2>&1

# compile java code into classes/ dir

find src -type f -name *.java | xargs nxjc -d classes

# make the nxj program

cd classes
nxjlink -o ../ProgramName.nxj ProgramName
cd ..

# upload the program

nxjupload -r ProgramName.nxj

The api documentation is available here: http://www.lejos.org/nxt/nxj/api/index.html