java error: Could not find the main class:

kaza · 04-24-2011, 12:08 AM

Hello,

I recently downloaded a java app (logbook manager with IR interface
for a "Galelo sol" diving computer) and when I attempted to run it,
I've got an error:

Code:

<localhost>.../JTrak_119_linux>java -jar jtrak_linux.jar
Exception in thread "main" java.lang.NoClassDefFoundError: de/frobese/jtrak/model/LogbuchManager
Caused by: java.lang.ClassNotFoundException: de.frobese.jtrak.model.LogbuchManager
	at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
Could not find the main class: de.frobese.jtrak.app.JTrakLinux. Program will exit.

When I open the file "jtrak_linux.jar" with archive manager,
I can find in it a file

/de/frobese/jtrak/app/JTrakLinux.class

the path looks like what "java" attempted to search for
(at least, relative to the "jar" file). It's the first
time I attempt to lauch java app from a ".jar" archive
so it's possible I have some setup problem (I have
a"NightVision java app which starts OK but it's
started by a rather complex script and not by "-jar"
argument).

Do I have to "setenv" some env. variable?

TIA for any help,
kaza.

CroMagnon · 04-24-2011, 04:32 AM

I think the problem class is actually de.frobese.jtrak.model.LogbuchManager, do you have this class? It might be in another jar file, in which case you probably need to add that jar file to your CLASSPATH variable, or your command line:

java -cp path/to/lib/with/LogbuchManager -jar jtrak_linux.jar

There should be a script or batch file or something with this sort of information if it's needed to run the app... does it come with any files other than the main jtrak_linux jar?

kaza · 04-24-2011, 09:56 AM

Hi CroMagnon, thanks for the reply.

In the same directory where the main ".jar" file resides there is a "lib" directory with
few more ".jar" files, here's the output of "ls -lR":

Code:

.:
total 72
-rwxr-xr-x. 1 user user  1771 Jul 03 2009 11:56:26 jtrak_linux.jar
drwxr-xr-x. 2 user user  4096 Jul 12 2009 21:51:06 lib
-rwxr-xr-x. 1 user user 61466 Jul 03 2009 12:46:28 libirsock.so

./lib:
total 4784
-rwxr-xr-x. 1 user user   29770 Jul 03 2009 11:56:26 comm.jar
-rwxr-xr-x. 1 user user   81567 Jul 03 2009 11:56:26 FormatedTextFields-2.0.jar
-rwxr-xr-x. 1 user user  696567 Jul 03 2009 11:56:26 hsqldb.jar
-rwxr-xr-x. 1 user user   34260 Jul 03 2009 11:56:26 irsocket.jar
-rwxr-xr-x. 1 user user  150793 Jul 03 2009 11:56:26 jdom.jar
-rwxr-xr-x. 1 user user  500623 Jul 03 2009 11:56:26 jh.jar
-rwxr-xr-x. 1 user user   45720 Jul 03 2009 11:56:26 jir.jar
-rwxr-xr-x. 1 user user 1152645 Jul 03 2009 11:56:26 jtrak_help.jar
-rwxr-xr-x. 1 user user  412718 Jul 03 2009 11:56:26 JTrak.jar
-rwxr-xr-x. 1 user user  222725 Jul 03 2009 11:56:26 jtrak_resources.jar
-rwxr-xr-x. 1 user user  324303 Jul 03 2009 11:56:26 local_extensions.jar
-rwxr-xr-x. 1 user user  352668 Jul 03 2009 11:56:26 log4j-1.2.8.jar
-rwxr-xr-x. 1 user user   59347 Jul 03 2009 11:56:26 MRJAdapter.jar
-rwxr-xr-x. 1 user user  802216 Jul 03 2009 11:56:26 poi-2.5.1-final-20040804.jar

Inside the file "JTrak.jar" there is (among many others) the file:

/de/frobese/jtrak/model/LogbuchManager

so it seems I have to explain to java to look there.
Looking at the contents of the file

/META-INF/MANIFEST.MF

I see:

Code:

Manifest-Version: 1.0
Ant-Version: Apache Ant 1.7.0
Created-By: 1.4.2-90 (Apple Inc.)
Main-Class: de.frobese.jtrak.app.JTrakLinux
Class-Path: lib/jtrak_resources.jar lib/jtrak.jar lib/log4j-1.2.8.jar 
 lib/FormatedTextFields-2.0.jar lib/comm.jar lib/hsqldb.jar lib/irsock
 et.jar lib/jh.jar lib/jir.jar lib/jtrak_help.jar

BTW, the Class-Path is not a single line wrapped to 3 lines but 3 distinct lines
separated by "new line" and even breaking the "lib/irsock" and what looks like its remaining
"et.jar"

Should I get all of the text after "Class-Path to be a single line?

I attempted adding a class path with the "-cp" but got the same error:

Code:

<localhost>.../JTrak_119_linux>java -cp lib jtrak_linux.jar
Exception in thread "main" java.lang.NoClassDefFoundError: jtrak_linux/jar
Caused by: java.lang.ClassNotFoundException: jtrak_linux.jar
	at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
Could not find the main class: jtrak_linux.jar. Program will exit.

What am I missing?

TIA for any ideas,
kaza.

Quote:

Originally Posted by CroMagnon

I think the problem class is actually de.frobese.jtrak.model.LogbuchManager, do you have this class? It might be in another jar file, in which case you probably need to add that jar file to your CLASSPATH variable, or your command line:

java -cp path/to/lib/with/LogbuchManager -jar jtrak_linux.jar

There should be a script or batch file or something with this sort of information if it's needed to run the app... does it come with any files other than the main jtrak_linux jar?

CroMagnon · 04-24-2011, 05:41 PM

Try it like this:

Code:

java -cp lib/jtrak_linux.jar -jar jtrak_linux.jar

I'm not overly familiar with java apps, but from my java(1) man page it sounds like the manifest overrides the command line classpath anyway, so this may make no difference (I'm on a Mac, so it's possible your implementation is different). The format of the manifest is ok according to the manifest spec, though I would probably try to keep individual items whole, instead of splitting them. As long as a line starts with a space, it is a continuation line.

Another option is just extracting the jar file and running the main class yourself, setting CLASSPATH to include everything:

Code:

export CLASSPATH=$CLASSPATH:lib/*
java de.frobese.jtrak.app.JTrakLinux

mrcheeks · 04-25-2011, 07:11 AM

Try the following code

Code:

APP_FOLDER=FULL_PATH_OF_JTRACK_FOLDER_LOCATION

MAINCLASS="de.frobese.jtrak.app.JTrakLinux"
JTRAK_CLASSPATH=.

for file in `ls $APP_FOLDER/lib/*.jar`; do JTRAK_CLASSPATH=$JTRAK_CLASSPATH:$file; done

java -Djava.library.path=$APP_FOLDER -cp $JTRAK_CLASSPATH $MAINCLASS

kaza · 06-23-2011, 12:48 PM

Sorry for so long a gap, other pressing things to do.

I had a little "progress": when I used the command:

java -cp lib/* -jar jtrak_linux.jar

and the error message changed, meaning giving the list of all *.jar files in the "lib"
directory caused java to find the previously not found class:

Code:

<localhost>.../JTrak_119_linux>java -cp lib/* -jar jtrak_linux.jar
Exception in thread "main" java.lang.NoClassDefFoundError: lib/FormatedTextFields-2/0/jar
Caused by: java.lang.ClassNotFoundException: lib.FormatedTextFields-2.0.jar
	at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
Could not find the main class: lib/FormatedTextFields-2.0.jar. Program will exit.

Please pay attention that the class path Java attempted to search for was: "lib/FormatedTextFields-2/0/jar"
while the file existing in the "lib" directory is named: "FormatedTextFields-2.0.jar".
It looks like Java mis-interpreted the dots in the file name as a class hierarchy delimiter
and replaced them with "/" characters. I attempted renaming the file to "FormatedTextFields-2_0.jar"
but it didn't allowed Java to find it, maybe because in the "manifest" file
the list of files in the "lib" directory contains the original name.

So, is there a way to alter Java's interpretation of the dots in filename of *.jar archives?

TIA for any help,
kaza.

Quote:

Originally Posted by mrcheeks

Try the following code

Code:

APP_FOLDER=FULL_PATH_OF_JTRACK_FOLDER_LOCATION

MAINCLASS="de.frobese.jtrak.app.JTrakLinux"
JTRAK_CLASSPATH=.

for file in `ls $APP_FOLDER/lib/*.jar`; do JTRAK_CLASSPATH=$JTRAK_CLASSPATH:$file; done

java -Djava.library.path=$APP_FOLDER -cp $JTRAK_CLASSPATH $MAINCLASS