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Java NoClassDefFoundError occurring even when the class path is added

I'm trying to compile and run the PercolationVisualizer in https://github.com/samet/Coursera-Algorithms-I-Assignment-1. According to http://introcs.cs.princeton.edu/java/stdlib/, the required dependencies StdDraw.java and In.java should be present in the stdlib package.
After cloning the repository, I copied stdlib.jar to the src directory and then compiled PercolationVisualizer using the following command:
javac -cp .:stdlib.jar PercolationVisualizer.java
(I did the same for Percolation.java). However, when I try to run the program using java PercolationVisualizer, I get the following error:
Exception in thread "main" java.lang.NoClassDefFoundError: In
at PercolationVisualizer.main(PercolationVisualizer.java:62)
Caused by: java.lang.ClassNotFoundException: In
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 1 more
I don't understand the NoClassDefFoundError for In, since it should be included in stdlib. Can anyone explain this behavior?

If you are on Windows, use the semicolon as CLASSPATH separator ..
javac -cp ".;stdlib.jar" PercolationVisualizer.java Percolation.java WeightedQuickUnionUF.java PercolationStats.java
If you are on linux/*nix, use the colon as CLASSPATH separator ...
javac -cp ".:stdlib.jar" PercolationVisualizer.java Percolation.java WeightedQuickUnionUF.java PercolationStats.java
For more information look here
If you want to debug the process of compilation, use the "-verbose" flag. It will display you CLASSPATH, the "lodaing jar_file ..." statements. If it has not recognized your jar file, it will now show the "loading" statement.

I finally unjar'd stdlib.jar into the working directory, after which the compilation worked. (This is indeed the first method to use stdlib described in http://introcs.cs.princeton.edu/java/stdlib/).

could not find the main class java error

I was having trouble with a could not find main class error with a somewhat complicated program I was working on. To eliminate possible problems I decided to try a hello world program to see if I could get that to work. I am working on a server which I'm pretty sure is running Red Hat Enterprise 6. I followed these steps provided by Bart Kiers in answer to this question:
create a file called HelloWorld.java;
paste the code posted below
inside HelloWorld.java: compile it by executing the command: javac
HelloWorld.java in the same folder as HelloWorld.java is in;
execute the code by doing: java -cp . HelloWorld in the same folder as
HelloWorld.java is in.
I get the following error after the last step:
Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorld/
Caused by: java.lang.ClassNotFoundException: HelloWorld.
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: HelloWorld.. Program will exit.
If I type java -version, the version info displays, suggesting that my PATH variable is set correctly. Does anyone have any other suggestions for things that might be causing this error? Thanks!

Looks like you are putting an period at the end of your class name:
java -cp . HelloWorld.
Do this instead
java -cp . HelloWorld

Works in sbt but not raw Java: after using `javac` to compile a .class file, why can't `java` find it?

I used ObjectWeb's ASMifier to get a 'HelloDump.java', and added classloader and a main method to load and run a spoofed "HelloWorld".
If I run 'HelloDump.java' in the build tool sbt, everything works fine and outputs "HelloWorld!".
But if I use raw Java, it breaks. 'HelloDump.java' seems to compile OK, but the resulting 'HelloDump.class' is clearly present, yet doesn't seem to be recognized (check the sequence below):
$ julianpeeters#julianpeeters-virtual-machine ~/asm-example $ javac -cp lib/asm-all-4.1.jar HelloDump.java
$ julianpeeters#julianpeeters-virtual-machine ~/asm-example $ ls
DumpLoader.java.bak HelloDump.class.bak Hello.java.bak
Hello.class.bak HelloDump$DynamicClassLoader.class lib
HelloDump.class HelloDump.java README.md
$ julianpeeters#julianpeeters-virtual-machine ~/asm-example $ java -cp lib/asm/all/4.1.jar HelloDump
Exception in thread "main" java.lang.NoClassDefFoundError: HelloDump
Caused by: java.lang.ClassNotFoundException: HelloDump
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: HelloDump. Program will exit.
Explicitly adding . to the classpath doesn't help either.
So why does this work in sbt, but not in raw Java, and how can I fix it?
Thanks, any advice is appreciated,
-Julian

Add . to your CLASSPATH, so your command becomes:
java -cp lib/asm-all-4.1.jar:. HelloDump
The reason the JVM cannot find the class is that it looks only on the classpath and nowhere else.

NoClassDefFoundError without any class name

I am trying to run a java task from ant. I am trying to run the "org.apache.tools.ant.launch.Launcher" class. I keep on getting the "NoClassDefFoundError" without any class name being specified. I am also getting a "ClassNotFoundException" along with that displaying a message "Could not find the main class: . Program will exit". Here's a snippet of the error
[java] Exception in thread "main" java.lang.NoClassDefFoundError:
[java] Caused by: java.lang.ClassNotFoundException:
[java] at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
[java] at java.security.AccessController.doPrivileged(Native Method)
[java] at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
[java] at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
[java] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
[java] at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
[java] at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
[java] Could not find the main class: . Program will exit.
[java] Java Result: 1
Now I am trying to run an ant class from an ant jar and i specifiy the classpath where this class file resides using the "classpathref" attribute, however I still get this message. I checked the ant jar to check the Manifest and the "main" class is specified properly (it's "org.apache.tools.ant.launch.Launcher") . I have exhausted all my resources. Please help ! ! !
ps: My environment is Eclipse on Ubuntu 9.04

Most likely your classpath is misconfigured.
At a minimum the CLASSPATH should include:
ant.jar and ant-launcher.jar
jars/classes for your XML parser
the JDK's required jar/zip files
(from the ant manual)
Also you seem to be relaunching ant in the current directory (executing the same build.xml). Maybe you'll want to set the "dir" property.

It looks like the Ant task is trying to run Java, but is somehow passing an empty string to the JVM as the name of the class to run. I can get the same stacktrace if I run the JVM directly with a quoted empty string:
C:\>java ""
Exception in thread "main" java.lang.NoClassDefFoundError:
Caused by: java.lang.ClassNotFoundException:
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: . Program will exit.
(This is on Windows, but I don't think that makes much of a difference.)
I can only suggest following up on Alexander Pogrebnyak's comment to akf's answer. Perhaps the webtest.lib property has spaces in it?
Also, is there a good reason for calling ant directly via java, rather than using the ant task?

https://blogs.oracle.com/sreekanth/entry/java_lang_noclassdeffounderror_org_codehaus
java.lang.NoClassDefFoundError: org/codehaus/plexus/classworlds/launcher/Launcher
By sreekanth on Nov 23, 2010
Recently when I am trying to run some Maven scripts, I am getting this exception:
Exception in thread "main" java.lang.NoClassDefFoundError: org/codehaus/plexus/classworlds/launcher/Launcher
Caused by: java.lang.ClassNotFoundException: org.codehaus.plexus.classworlds.launcher.Launcher
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: org.codehaus.plexus.classworlds.launcher.Launcher. Program will exit.
After spending some time trying various combinations , I found that this is because I have both M2_HOME and M3_HOME set in my environment variables.Once I removed M2_HOME from my environment variables, I could get this working back again.May be this could save some serious time for some one.

This can be a misleading error that is not actually about a class missing from the classpath. If you are using Tomcat it can be due to missing conf files in $CATALINA_BASE/conf
It could also be a misconfigured ant installation, please check your JAVA_HOME and ANT_HOME env variables or try another ant installation.

Ant launcher expects the following params
java -Dant.home=c:\ant org.apache.tools.ant.launch.Launcher [options] [target]
I am affraid we can't proceed answering you if you don't paste your whole build.xml file.
Just try to give your full sample as below:
<java
classname="org.apache.tools.ant.launch.Launcher"
fork="true"
failonerror="true"
dir="${sub.builddir}"
timeout="4000000"
taskname="startAnt"
>
<classpath>
<pathelement location="${ant.home}/lib/ant-launcher.jar"/>
</classpath>
<arg value="-buildfile"/>
<arg file="${sub.buildfile}"/>
<arg value="-Dthis=this"/>
<arg value="-Dthat=that"/>
<arg value="-Dbasedir=${sub.builddir}"/>
<arg value="-Dthe.other=the.other"/>
<arg value="${sub.target}"/>
</java>
This would be extremely helpful to provide you with a possible misunderstanding.
Hope this helps,
Ernani

From this line:
[java] Could not find the main class: . Program will exit.
it looks as though your call to java.exe is finding a . where it expects a class name. Perhaps you are trying to indicate the classpath on the commandline but are neglecting to preface that with the -cp or -classpath flag.

When in doubt, invoke ant -v and watch all your variable declarations, and the whole commandline sent to Java.
Certain path-like quantities are eagerly evaluated, while others are lazily evaluated. I've had plenty of problems where I used one of the former, when my Ant script intended to create a jar that would be used by a later task. Then by the time I invoked the call, it had already pruned my jar from the classpath.
If I had to make a wild guess, I'd bet your commandline looked something like:
java ... -classpath org.apache.tools.ant.launch.Launcher
instead of
java ... -classpath foo.jar;bar.jar org.apache.tools.ant.launch.Launcher
like you expected

I had a similar problem recently. The culprits were 2 tags under the java task, that didn't have their values set, so they resulted in 2 empty command arguments and in the end in 2 spaces in the command line.
For some reason Unix doesn't handle it right. Both Red Hat 5 and Ubuntu displayed the same error. It was OK on Windows 7.
Setting those arguments to have default dummy values solved the issue.

How to invoke groovy with 'java' from command line

I have to ship some groovy code to some users that have only java installed (no grooy, no $groovy_home, etc). I'm trying to invoke groovy from the commandline but I'm having no luck. Here's my bat file:
java -classpath .;lib;bin;bin-groovy introspector.AclCollector
And here's my exception:
Exception in thread "main" java.lang.NoClassDefFoundError: groovy/lang/GroovyObject
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
Caused by: java.lang.ClassNotFoundException: groovy.lang.GroovyObject
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)
... 12 more
Could not find the main class: introspector.AclCollector. Program will exit.
Does anyone have a clue? I have 'groovy-all-1.6-beta-1.jar' in \lib dir.

You have here another example of Groovy app called from Java (in this case, from ant, but the general idea is the same).
java -cp [...];%GROOVY_HOME%/embeddable/groovy-all-1.5.4.jar;[..]
As mentioned by frankowyer, you have the exact groovy jar explicitly listed on the classpath arguments of the java.
Since your clients do not have special environment variable, just replace the %GROOVY_HOME%/... with the complete path to:
groovy.jar or
goovy-all-VERSION.jar (to minimize any conflict with other libraries)

I think you need to explicitly list the groovy jar in the classpath

One way to avoid problems with different class paths on different machines would be to bundle all the necessary dependencies into one single jar, this would also make distribution to users easier. This can be done with this 'GroovyWrapper' script. The default jars (embeddable/groovy-all-.jar and lib/commons.jar) are included by default in the script and if you require other JARS they can easily be added.
See http://docs.codehaus.org/display/GROOVY/WrappingGroovyScript for the full script and instructions.
Here's an example of how to use GroovyWrapper:
Say you have groovy script HelloWorld.groovy, use GroovyWrapper for building HelloWorld.jar, as follows:
$ groovy GroovyWrapper -c -m HelloWorld
GroovyWrapper will compile the script HelloWorld.groovy to HelloWorld.class, and creates a self-executable jar HelloWorld.jar.
Now you can use the HelloWorld.jar for launching the HelloWorld script, simply by running:
$ java -jar HelloWorld.jar

GREAT ANSWER by VonC:
....... Since your clients do not have special environment variable,
just replace the %GROOVY_HOME%/... with the complete path to:
groovy.jar or
goovy-all-VERSION.jar (to minimize any conflict with other libraries)........
this is for windows Vista:
In System Properties | Environmental Variables | User variables:
Variable Name GROOVY_HOME set to C:\groovy\Groovy-1.8.5
and the Variable Name CLASSPATH value's set to include .;%GROOVY_HOME%\embeddable\groovy-all-1.8.5.jar
Don't make the mistake I did(spinning my wheels a bit), of not prep-ending the path of the 'groovy-all' with ".;" (dot and semi-colon): as the path needs the base folder you're in for finding the main class(strange as it seems)

Watch out of [~]!
java -cp .:~/path-to-groovy-all.jar YourClassName # does not work
java -cp ~/path-to-groovy-all.jar:. YourClassName # works
java -cp .:/full/path/to/goovy-all.jar YourClassName # works
In first line tilde is not processed by bash, and java can not understand it.
In second line tilde is replaced by bash and everything works fine.