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fadedbee avatar Ubuntu

How to fix java.lang.ClassNotFoundException: gnu.io.CommPortIdentifier with libRXTX on Ubuntu 20.04?

us flag
fadedbee

I have the following error:

$ sudo java -jar /home/fadedbee/tc65sh-1.4.0/bin/tc65sh.jar -Djava.library.path=/usr/lib/jni/ -cp /usr/share/java/RXTXcomm.jar -p /dev/ttyUSB0 -b 115200 -f push.txt
tc65sh v1.4.0
processing command file push.txt
connecting /dev/ttyUSB0 with 115200 baud, flowControl r
Exception in thread "main" java.lang.NoClassDefFoundError: gnu/io/CommPortIdentifier
    at org.tc65sh.device.Device.connect(Device.java:56)
    at org.tc65sh.Main.exec(Main.java:102)
    at org.tc65sh.Main.main(Main.java:59)
Caused by: java.lang.ClassNotFoundException: gnu.io.CommPortIdentifier
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
    ... 3 more

I've installed libRXTX and all the files appear in the correct places:

$ ls -lA /usr/lib/jni/
total 148
-rw-r--r-- 1 root root 22696 May  9  2018 librxtxI2C-2.2pre1.so
lrwxrwxrwx 1 root root    21 May  9  2018 librxtxI2C.so -> librxtxI2C-2.2pre1.so
-rw-r--r-- 1 root root 14424 May  9  2018 librxtxParallel-2.2pre1.so
lrwxrwxrwx 1 root root    26 May  9  2018 librxtxParallel.so -> librxtxParallel-2.2pre1.so
-rw-r--r-- 1 root root 22688 May  9  2018 librxtxRaw-2.2pre1.so
lrwxrwxrwx 1 root root    21 May  9  2018 librxtxRaw.so -> librxtxRaw-2.2pre1.so
-rw-r--r-- 1 root root 22704 May  9  2018 librxtxRS485-2.2pre1.so
lrwxrwxrwx 1 root root    23 May  9  2018 librxtxRS485.so -> librxtxRS485-2.2pre1.so
-rw-r--r-- 1 root root 59824 May  9  2018 librxtxSerial-2.2pre1.so
lrwxrwxrwx 1 root root    24 May  9  2018 librxtxSerial.so -> librxtxSerial-2.2pre1.so

$ ls -lA /usr/share/java/ | grep RXTX
-rw-r--r-- 1 root root   63027 May  9  2018 RXTXcomm-2.2pre2.jar
lrwxrwxrwx 1 root root      20 May  9  2018 RXTXcomm.jar -> RXTXcomm-2.2pre2.jar

I can see the correct class inside of the jar file:

$ strings /usr/share/java/RXTXcomm.jar | grep CommPortIdentifier
gnu/io/CommPortIdentifier.class
gnu/io/CommPortIdentifier.classPK

How can I help Java find the class?

(I've already tried changing the option order to sudo java -Djava.library.path=/usr/lib/jni/ -cp /usr/share/java/RXTXcomm.jar -jar /home/fadedbee/tc65sh-1.4.0/bin/tc65sh.jar -p /dev/ttyUSB0 -b 115200 -f push.txt but the error remains.)

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Bodo avatar
pt flag
Bodo
Not directly related to your problem, but running the program as `root` might be a security risk. If you don't have the permissions to use `/dev/ttyUSB0` as a normal user you should add the user to the group that owns the tty device. see https://askubuntu.com/a/133244/1186757
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fadedbee avatar
us flag
fadedbee
@Bodo, Yes, you're correct, but first I'll get it to run, then I'll sort out permissions.
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Bodo avatar
pt flag
Bodo
Did you recompile the sources or did you just run the binary JAR from `tc65sh-1.4.0.zip`? Just a guess: This seems to be a fairly old software, and the README file states "Java SE 6 must be installed on your machine to run TC65SH." Could there be an incompatibility between `tc65sh.jar` compiled probably with Java 6 and `RXTXcomm.jar` which might be compiled with a newer version or even might have changed.
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N0rbert avatar
zw flag
N0rbert
Run first `sudo usermod -a -G dialout $USER` then reboot and retry without `sudo`.
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fadedbee avatar
us flag
fadedbee
@Bodo I just ran the binary JAR.
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Score:0
fadedbee avatar Ubuntu
us flag
fadedbee

The solution was to use:

$ sudo java -Djava.library.path=/usr/lib/jni/ -cp /usr/share/java/RXTXcomm.jar:/home/fadedbee/tc65sh-1.4.0/bin/tc65sh.jar org.tc65sh.Main -p /dev/ttyUSB0 -b 115200 -f push.txt

It solves the first problem, but now I'm left with:

$ sudo java -Djava.library.path=/usr/lib/jni/ -cp /usr/share/java/RXTXcomm.jar:/home/fadedbee/tc65sh-1.4.0/bin/tc65sh.jar org.tc65sh.Main -p /dev/ttyUSB0 -b 115200 -f push.txt
tc65sh v1.4.0
processing command file push.txt
connecting /dev/ttyUSB0 with 115200 baud, flowControl r
RXTX Warning:  Removing stale lock file. /var/lock/LCK..ttyUSB0
initializing device
forcing obex mode
java.io.IOException: obex response timeout after 5001 ms and 33 bytes
    at org.tc65sh.device.Device.receiveObexResponse(Device.java:543)
    at org.tc65sh.device.Device.openObexMode(Device.java:326)
    at org.tc65sh.device.Device.obexOpenObexMode(Device.java:127)
    at org.tc65sh.Main.exec(Main.java:110)
    at org.tc65sh.Main.main(Main.java:59)
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