Exception in thread "main" java.lang.NoClassDefFoundError from JAR

Question

i'm trying to run a jar executable from a shell file. the path of my jar :

/home/flussi/xmlEncoder/encoder.jar

but I always get this error:

    Exception in thread "main" java.lang.NoClassDefFoundError: smaf.encoder.Encoder
   at java.lang.Class.initializeClass(libgcj.so.7rh)
Caused by: java.lang.ClassNotFoundException: java.nio.file.LinkOption not found in gnu.gcj.runtime.SystemClassLoader{urls=[file:/home/flussi/xmlEncoder/encoder.jar], parent=gnu.gcj.runtime.ExtensionClassLoader{urls=[], parent=null}}
   at java.net.URLClassLoader.findClass(libgcj.so.7rh)
   at java.lang.ClassLoader.loadClass(libgcj.so.7rh)
   at java.lang.ClassLoader.loadClass(libgcj.so.7rh)
   at java.lang.Class.initializeClass(libgcj.so.7rh)

shell command

java -jar /home/flussi/xmlEncoder/encoder.jar

Possible duplicate of [How to solve java.lang.NoClassDefFoundError?](https://stackoverflow.com/questions/17973970/how-to-solve-java-lang-noclassdeffounderror) — OcelotcR, Mar 14 '18 at 10:37
Are you using gcj? Because its standard library seems to be from before the time Java NIO was introduced. — Federico klez Culloca, Mar 14 '18 at 10:37
actually I don't know, the program is on FTP server, i'm not the owner, so i don't really know — Giulio Angioli, Mar 14 '18 at 10:45
What program? The one you are trying to run? Or the Java installation you are trying to run it with? The problem is *actually* with the Java *installation*. — Stephen C, Mar 14 '18 at 10:46

Stephen C · Accepted Answer · 2018-03-14T12:22:12.977

1

There is evidence in the stacktrace that you are trying to use the GCJ tool chain to run that JAR file. (And the evidence in your comment below confirms this.)

This is the real problem.

Unfortunately, development of GCJ stalled before they completed support for Java 1.5. And it looks like you are trying to run a JAR file that depends on a Java 1.7 class (java.nio.file.LinkOption)

My recommendation:

uninstall the GCJ java packages that have been installed
install OpenJDK Java 8 (1.8) packages or later¹ from your package manager or download and install Java 8 or later RPMs from the Oracle site.

If you don't manage the machine, get the managers to do it. Or try to run the JAR file somewhere else.

It would most likely require a significant rewrite of the application to make it work on GCJ. And it would be wasted effort, since GCJ is effectively a dead Java platform.

^{1 - Java 7 would work, but is was EOLed a couple of years ago.}

edited Mar 14 '18 at 12:22

answered Mar 14 '18 at 10:45

Stephen C

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now i'm using JDK 1.5, what a kind version of JDK i suppose that I need? – Giulio Angioli Mar 14 '18 at 10:50
The stacktrace shows that you are actually >>using<< the GCJ `java` command. It is not real Java 1.5. Run `java -version` or `java --version` and see what it outputs. – Stephen C Mar 14 '18 at 10:58
I would recommend the latest update to Java 8. Anything earlier than Java 8 has been end-of-lifed. Java 9 is just a bit too "raw" at the moment. – Stephen C Mar 14 '18 at 11:00
java version "1.4.2" gij (GNU libgcj) version 4.1.2 20080704 (Red Hat 4.1.2-55) – Giulio Angioli Mar 14 '18 at 11:04
As I suspected., that is NOT JDK 1.5. It is the GCJ flavor of Java 1.4.2. And, as I noted above, you actually need Java 1.7 or later. – Stephen C Mar 14 '18 at 11:07
Yup. If you want to run that JAR file. – Stephen C Mar 14 '18 at 11:30
Thank you so much! – Giulio Angioli Mar 14 '18 at 14:05

Abhijit Pritam Dutta · Answer 2 · 2018-03-14T11:02:02.980

0

Hi Best way to run a java application is to set CLASS_PATH and PATH variable first. If your current jar file depends on external jar files you will face lots of problem. Better set your path variable like below and run the application:-

 #!/usr/bin/ksh
 export PATH=/usr/java/bin:$PATH
 # =/usr/java/bin is your java bin folder

 #set environment variable CP with all the jar libraries
 CP=/home/flussi/xmlEncoder/encoder.jar 
 CP=${CP}:/other/jar/somejar.jar

 java -Xmx256M -classpath "$CP" "com.myproj.Example"

This is com.myproj.Example your java class file inside encoder.jar where you have declared public static void main

edited Mar 14 '18 at 11:02

answered Mar 14 '18 at 10:49

Abhijit Pritam Dutta

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Not sure. But I always follow the above approach. Thanks for the information. :-) – Abhijit Pritam Dutta Mar 14 '18 at 10:53
The `-cp` / `-classpath` options and `$CLASSPATH` are **ignored** if you use the `-jar` option. It is in the manual. And note that the JAR filename must follow immediately after `-jar`. – Stephen C Mar 14 '18 at 10:53
OK ... but just because you do things one way does not mean that another way is wrong ... *"you can not simply run a java application like that"*. Actually, you simply can! – Stephen C Mar 14 '18 at 10:56
@StephenC, answer modified. – Abhijit Pritam Dutta Mar 14 '18 at 11:02

Exception in thread "main" java.lang.NoClassDefFoundError from JAR

2 Answers2