A story I was addicted to when trying to serially communicate with Arduino using Eclipse on macOS Sierra.

Execution environment

OS : macOS Sierra
java : java1.7
Eclipse : Eclipse Java EE IDE for Web Developers.(version: neon)

RXTX

Overview

A library for serial communication with microcomputers such as Arduino. Windows, Mac and Linux are supported. I proceeded with reference to the following page. http://cho-kotan.blogspot.jp/2012/10/javaavrmacjavaavr.html

download

Download rxtx-2.1-7-bins-r2.zip on the following page http://rxtx.qbang.org/wiki/index.php/Download

Move files

Extract the downloaded file and move the downloaded file to the folder for the external library by the following command.

$ cd <download_folder>/rxtx-2.1-7-bins-r2
$ sudo cp RXTXcomm.jar /Library/Java/Extensions/
$ sudo cp Mac_OS_X/librxtxSerial.jnilib /Library/Java/Extensions/

Also, since a directory for exclusive control of RXTX is required, execute the following command.

$ sudo mkdir /var/lock
$ sudo chmod 777 /var/lock

Pass through eclipse

In eclipse, right-click the current project folder-> [Properties]
[Java Build Path]-> [Library]
[Add External JAR]-> Select RXTXcomm.jar in the Extensions directory.
Select the Extensions directory for [Native Library Location] in RXTXcomm.jar that appears in [JAR and Class Folders on Build Path].
OK

Run

Copy and paste the source code of the following URL that you referred to and execute it as it is. http://cho-kotan.blogspot.jp/2012/10/javaavrmacjavaavr.html

Then, the following error

java.lang.UnsatisfiedLinkError: /Library/Java/Extensions/librxtxSerial.jnilib: dlopen(/Library/Java/Extensions/librxtxSerial.jnilib, 1): no suitable image found.  Did find:
/Library/Java/Extensions/librxtxSerial.jnilib: no matching architecture in universal wrapper thrown while loading gnu.io.RXTXCommDriver

I'm getting an error about the link, but I'm angry that I got an error while reading gnu.io.RXTXcommDriver, so it seems that the path is working properly. It didn't work no matter how many times I tried it, so I investigated it.

It was a version issue

I didn't know if it wasn't supported by Sierra or java, so I searched variously and found the following page. http://blog.brianhemeryck.me/installing-rxtx-on-mac-os-mountain-lion/

According to the article, it seems that the file librxtxSerial.jnilib downloaded from the official page only supports Java 5, and similar errors may occur in Java 6 and later from Mountain Lion (Eclipse). It may depend on the environment ...).

Therefore, delete the librxtxSerial.jnilib from the Extensions file, and download the Java 6 compatible one on the following page. http://blog.iharder.net/2009/08/18/rxtx-java-6-and-librxtxserial-jnilib-on-intel-mac-os-x/#comment-163295

$ rm /Library/Java/Extensions/librxtxSerial.jnilib
$ cp <download_folder>/librxtxSerial.jnilib /Library/Java/Extensions/

Run again

Since the path of the external JAR file has been set in Eclipse in the previous setting, execute it in Eclipse as it is when the above command is completed.

The value read from Arduino was displayed on the console safely.