Develop Reference

Java cannot find a class in a .jar file in Linux

I built a java program in Eclipse in Windows and it worked well. The program included 5 java classes and 5 jar library files.
Then I copied all *.java files and *.jar files to Linux. After I compiled and run it, I got an exception, the class PaserException of htmlparser.jar was not found.
Exception in thread "main" java.lang.NoClassDefFoundError: org/htmlparser/util/ParserException
Caused by: java.lang.ClassNotFoundException: org.htmlparser.util.ParserException
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
I just begin to learn Linux so I'm not sure if I compiled and run it correctly.
All of my files(*.java and *.jar) are in the same directory, and my operation is in this directory.
To compile:
javac -cp ./htmlparser.jar:./filterbuilder.jar:./sitecapturer.jar:./thumbelina.jar:./htmllexer.jar *.java
To run:(the main method is in Crawler class, main method requires at lease 1 argument)
java -cp ./htmlparser.jar:./filterbuilder.jar:./sitecapturer.jar:./thumbelina.jar:./htmllexer.jar Crawler arg0 arg1
Then I got the exception above. Did I compile and run it correctly? Why did I got this exception? Thanks.

The folder that holds the class file (.) is not on the classpath. Add another :. to the classpath:
java -cp ./htmlparser.jar:./filterbuilder.jar:./sitecapturer.jar:./thumbelina.jar:./htmllexer.jar:. Crawler arg0 arg1

java.lang.NoClassDefFoundError at Runtime: Need Class not on Classpath

I have tried several approaches as suggested on this website as well as several others to no avail.
-Running Angstrom embedded Linux, OpenJDK6, Shark VM.
File Structure
All .java and .jar files are stored in directory ./src
jarfiles: j1.jar j2.jar
Source code: Coder.java, WrapperClass.java
Compiling and Running
javac -cp j1.jar:j2.jar Coder.java WrapperClass.java
Successfully compiles, outputs Coder.class, WrapperClass.class, as well as several other files including Coder$1.class through Coder$6.class, as well as Coder$Main_thread.class and Coder$Progress_Bar_Thread.class, any insight onto what all these .class files are for?
Run attempts all terminate in java.lang.ClassNotFoundException.
~/coder/src: java Package.Coder
~/coder/src: java -cp jar1.jar:jar2.jar Package.Coder
~/coder: java ./src/Package.Coder
~/coder: java -cp jar1.jar:jar2.jar ./src/Package.Coder
Thank you very much for your help. I have run this on NetBeans and can verify that it's functional code, just a matter of getting it to run on Linux.
Stacktrace is:
Exception in thread "main" java.lang.NoClassDefFoundError: Package/Coder Caused by: java.lang.ClassNotFoundException: Package.Coder
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334)
Could not find the main class: Package.Coder. Program will exit

Assuming this structure
/coder
/src
/Package
/Coder.java
/WrapperClass.java
/j1.jar
/j2.jar
You will need to compile from /src as
javac -cp j1.jar:j2.jar Package/Coder.java Package/WrapperClass.java
This will create .class files in /Package. You can then run it, again from /src as
java -cp j1.jar:j2.jar Package.Coder
assuming the Coder class has a main method which is your entry point.

Runnig jar dependant java class file

java.lang.NoClassDefFoundError
I have a java program which is dependant on two jar files.
i compile the program using command :
javac -classpath jar1.jar:jar2.jar myprog.java and it compiles successfully.
But when i try to run the program using command : java -cp jar1.jar:jar2.jar myprog , it is throwing the java.lang.NoClassDefFoundError . please help , where am i wrong ?
i am using ubuntu 10.04.
Actual error :
Exception in thread "main" java.lang.NoClassDefFoundError: userapps/SelectionTask_classes/SelectionTask
Caused by: java.lang.ClassNotFoundException: userapps.SelectionTask_classes.SelectionTask
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: userapps/SelectionTask_classes/SelectionTask. Program will exit.
where SelectionTask is my class file generated after successful compilation.

Make sure that the current directory is also in the classpath. Try running with:
java -cp .:jar1.jar:jar2.jar myprog
if your compiled class file myprog.class is in the current directory.
(This assumes that your program is not in a package).

You need to add directory where your compiled java program (*.class) file is located. If it's in current directory then you could run it like this (notice "." which denotes current working directory):
java -cp .:jar1.jar:jar2.jar myprog

Look at the error, it's complaining about not being able to find "userapps.SelectionTask_classes.SelectionTask", which hints at the last entry in your classpath not beign specified correctly. Now, assuming that the JAR files you have specified are in the following directory structure:
./hadoop-0.20.1-core.jar
./lib/hadoopdb.jar
./userapps/SelectionTask_classes/
You would run:
java -cp hadoop-0.20.1-core.jar:lib/hadoopdb.jar:userapps/SelectionTask_classes/ myprog

Jythonc : How to use?

I am new to jython. Here is my failed attempt to use javac to complie my python script into class file.
rohit#rohit-laptop:~/backyard$ echo "print 'hi'" > test.py
rohit#rohit-laptop:~/backyard$ jython test.py
hi
rohit#rohit-laptop:~/backyard$ jythonc test.py
Warning: jythonc is unmaintained and will not be included in Jython-2.3. See http://jython.org/Project/jythonc.html for alternatives to jythonc. Add '-i' to your invocation of jythonc to turn off this warning
processing test
Required packages:
Creating adapters:
Creating .java files:
test module
Compiling .java to .class...
Compiling with args: ['/usr/bin/javac', '-classpath', '/usr/share/java/jython.jar:/usr/share/java/servlet-api-2.4.jar:/usr/share/java/libreadline-java.jar:./jpywork::/usr/share/jython/Tools/jythonc:/usr/share/jython/Lib:/usr/lib/site-python:__classpath__', './jpywork/test.java']
0
rohit#rohit-laptop:~/backyard$
rohit#rohit-laptop:~/backyard$ cd jpywork/
rohit#rohit-laptop:~/backyard/jpywork$ ls
test.class test.java test$_PyInner.class
rohit#rohit-laptop:~/backyard/jpywork$ java test
Exception in thread "main" java.lang.NoClassDefFoundError: org/python/core/PyObject
Caused by: java.lang.ClassNotFoundException: org.python.core.PyObject
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: test. Program will exit.
rohit#rohit-laptop:~/backyard/jpywork$
Please suggest the correct way.

Jython will automatically compile it into .class file on first execution, however in case you want to compile it, you can use standard library, find py_compile.py or compileall.py on Jython lib folder.

$ java test # is not the exact command to execute the class file
this class file requires jython.jar file to execute you have to give the jython.jar path at the run time.
#java -cp /home/litindia/jython-2.0.1/jython.jar:. test
-cp is compulsory /home/litindia/jython-2.0.1/jython.jar is my path where is jython.jar is present in my system, your path may be different. so please give the appropriate path.
And after the path :. is compulsory. Then file name is required.

problem related to MANIFEST.MF in jar

I have created jar in folder /usr/local/bin/niidle.jar.
And I have cerated MANIFEST.MF in jar as follows:
Manifest-Version: 1.0
Main-Class: com.ensarm.niidle.web.scraper.NiidleScrapeManager
Class-Path: hector-0.6.0-17.jar
And my 'hector-0.6.0-17.jar' file is present in following folder:
/Projects/EnwelibDatedOct13/Niidle/lib/hector-0.6.0-17.jar
And I have added this 'hector-0.6.0-17.jar' in niidle.jar folder as follows:
niidle.jar/lib/hector-0.6.0-17.jar
And when I run this using command:
java -jar /usr/local/bin/niidle.jar arguments....
then I am getting error message as follows:
Exception in thread "main" java.lang.NoClassDefFoundError: me/prettyprint/hector/api/Serializer
at com.ensarm.niidle.web.scraper.NiidleScrapeManager.main(NiidleScrapeManager.java:21)
Caused by: java.lang.ClassNotFoundException: me.prettyprint.hector.api.Serializer
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
... 1 more
And When I run again using different command as follows:
java -cp /Projects/EnwelibDatedOct13/Niidle/lib/hector-0.6.0-17.jar -jar /usr/local/bin/niidle.jar arguments.....
---------------Then also I am getting the same error message:--
Exception in thread "main" java.lang.NoClassDefFoundError: me/prettyprint/hector/api/Serializer
at com.ensarm.niidle.web.scraper.NiidleScrapeManager.main(NiidleScrapeManager.java:21)
Caused by: java.lang.ClassNotFoundException: me.prettyprint.hector.api.Serializer
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
... 1 more-------------
so tell me what is solution for that.or any modification in MANIFEST.MF in jar

java -cp /Projects/EnwelibDatedOct13/Niidle/lib/hector-0.6.0-17.jar -jar /usr/local/bin/niidle.jar arguments.....
You can't use the -cp switch together with the -jar switch.
From http://mindprod.com/jgloss/classpath.html:
If you use the -jar option, java.exe ignores the classpath. It will only look in that jar!! Try using the manifest Class-Path instead to get Java to look in auxiliary jars
And I have added this 'hector-0.6.0-17.jar' in niidle.jar folder as follows:
To my knowledge, you can't nest .jar files this way.
Since you have Class-Path: hector-0.6.0-17.jar you need to have the needle.jar and the hector-0.6.0-17.jar side by side and run niidle.jar from their common directory (using the -jar switch if you like).

Line niidle.jar/lib/hector-0.6.0-17.jar is confusing. Is niidle.jar directory or file?
I'd suggest you to post your full manifest, directory structure, command line you are using and current working directory.
But generally you should write in your manifest:
Class-Path: hector-0.6.0-17.jar
then put all jars in one directory. Let's call it foo.
Now open command prompt, go to foo and run
java -jar niidle.jar args...
And I believe that everything will work. Then if you wish play with location of your jars.

For setting up "jars within jars" take a look at this question:
Classpath including JAR within a JAR