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java.lang.NoClassDefFoundError when trying to instantiate class from jar

I did found quite a lot about this error, but somehow none of the suggested solutions resolved the problem.
I am trying to use JNA bindings for libgphoto2 under Ubuntu in Eclipse (moderate experience with Java on Eclipse, none whatsoever on Ubuntu, I'm afraid). The bindings in question I want to use are here:
http://angryelectron.com/projects/libgphoto2-jna/
I followed the steps described on that page, and made a simple test client that failed with the above error. So I reduced the test client until the only thing I tried to do was to instantiate a GPhoto2 object, which still produced the error. The test client looks like this:
import com.angryelectron.gphoto2.*;
public class test_class
{
public static void main(String[] args)
{
GPhoto2 cam = new GPhoto2();
}
}
The errors I get take up considerably more space:
Exception in thread "main" java.lang.NoClassDefFoundError: com/sun/jna/Structure
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at test_class.main(test_class.java:12)
Caused by: java.lang.ClassNotFoundException: com.sun.jna.Structure
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)
... 13 more
libgphoto2 itself is installed, it runs from the command line, I even have the development headers and am able to call GPhoto2 functions from python, so the problem can't be located there.
When looking at the .class files in Eclipse, however, they didn't have any definitions. So I figured that might be the problem, especially since there was an error when building the whole thing with ant (although the .jar was succesfully exported, from what I could make out the error concerned only the generation of documentation).
So I loaded the source into eclipse and built the .jar myself. At this occasion Eclipse stated there were warnings during the build (though no errors), but didn't show me the actual warnings. If anyone could tell me where the hell the build log went, that might already help something. I searched for it everywhere without success, and if I click on "details" in eclipse it merely tells me where the warnings occured, not what they were.
Be that as it may, a warning isn't necessarily devastating, so I imported the resulting Jar into the above client. I checked the .class files, this time they contained all the code. But I still get the exact same list of errors (yes, I have made very sure that the old library was removed from the classpath and the new ones added. I repeated the process several times, just in case).
Since I don't have experience with building jars, I made a small helloworld jar, just to see if I could call that from another program or if I'd be getting similar errors. It worked without a hitch. I even tried to reproduce the problem deliberately by exporting it with various options, but it still worked. I tried re-exporting the library I actully need with the settings that had worked during my experiment, but they still wouldn't run. I'm pretty much stuck by now. Any hints that help me resolve the problem would be greatly appreciated.

In addition to what #Paul Whelan has said. You might have better luck by just get the missing jar directly.
Get the missing library here, set the classpath and then re-run the application again and see whether it will run fine or not.

What version of java are you using com/sun/jna/Structure may only work with certain JVMs.
In general, packages such as sun., that are outside of the Java platform, can be different across OS platforms (Solaris, Windows, Linux, Macintosh, etc.) and can change at any time without notice with SDK versions (1.2, 1.2.1, 1.2.3, etc). Programs that contain direct calls to the sun. packages are not 100% Pure Java.
More details here

Your jar needs a MANIFEST.MF which tells your application where the library is found. Create the file in you project root-directory in eclipse and add the following lines:
Manifest-Version: 1.0
Class-Path: <PATH_TO_LIB__CAN_BE_RELATIVE>.jar // e.g Class-Path: ../test.jar
<empty line>
Right-click your project in eclipse, go to Export->next->next->next->Use existing manifest from workspace, select it and click on finish. This should work.
Another solution is to compile the classes into the jar itself with Maven.

NoSuchMethodError with Camel RouteDefinition class

I am trying to debug a Java / Maven project with a lot of depencies on various libraries.
When I run it on a Linux server the program starts up fine, but when I try to run it in Eclipse it throws the following exception:
Exception in thread "main" java.lang.NoSuchMethodError: org.apache.camel.model.RouteDefinition.getErrorHandlerBuilder()Lorg/apache/camel/ErrorHandlerFactory;
at org.apache.camel.spring.spi.SpringTransactionPolicy.wrap(SpringTransactionPolicy.java:69)
at org.apache.camel.model.PolicyDefinition.createProcessor(PolicyDefinition.java:133)
at org.apache.camel.model.ProcessorDefinition.makeProcessor(ProcessorDefinition.java:437)
at org.apache.camel.model.ProcessorDefinition.addRoutes(ProcessorDefinition.java:183)
at org.apache.camel.model.RouteDefinition.addRoutes(RouteDefinition.java:817)
at org.apache.camel.model.RouteDefinition.addRoutes(RouteDefinition.java:165)
at org.apache.camel.impl.DefaultCamelContext.startRoute(DefaultCamelContext.java:697)
at org.apache.camel.impl.DefaultCamelContext.startRouteDefinitions(DefaultCamelContext.java:1654)
at org.apache.camel.impl.DefaultCamelContext.doStartCamel(DefaultCamelContext.java:1441)
at org.apache.camel.impl.DefaultCamelContext.doStart(DefaultCamelContext.java:1338)
at org.apache.camel.impl.ServiceSupport.start(ServiceSupport.java:67)
at org.apache.camel.impl.ServiceSupport.start(ServiceSupport.java:54)
at org.apache.camel.impl.DefaultCamelContext.start(DefaultCamelContext.java:1316)
Now, I can see that the RouteDefinition class is in the camel-core-2.9.3,jar and I can see that this library is imported. So how come it doesn't see that method?
How do I go about debugging this?
Could I get info from the process running on the Linux server? For example can I get the list of Jars that are imported and the order in which they are imported?
Many thanks!

The error that you're getting is caused by Maven pulling in the wrong version. Try deleting all versions out of your local repo, add it explicitly to your pom, clean out all of your builds, pray to the eclipse gods, etc. If it still gives you the error, check your local repo to see which wrong versions it pulled in, figure out what depends on them, and add explicit ignores for them while keeping the explicit include.

Vert.x fails to "Run your module and see your changes immediately"

I am working with the Vert.x Gradle template hosted at the Vert.x Github space.
The build file suggests that there is a runModIDEA target that runs IDEA-built class files so that rebuild/redeploy is not required to pick up changes:
runModIDEA - run the module from the project resources in IDEA. This allows you to run the module without building it
first!
... yet the task does not exist per ./gradlew tasks.
I am not tied to this particular build task per se.
I just want a working auto-redeploy solution that enables me to see updates without a two minute rebuild/redeploy cycle.
EDIT: I also tried running it directly, pointing to InteliJ IDEA output classpath. It works fine, but doesn't pick up changes.
vertx runmod com.mycompany~vert-x-reverse-proxy~1.0.0-final -c conf.json -cp out/production/vert-x-reverse-proxy
EDIT: I also tried ./gradlew runmod -m, first changing vertx_classpath.txt so that the IDEA files (out/production) are looked at first. Still no redeploy. In fact, while it was running, I deleted the out directory and it continued working.
EDIT: I also tried vertx run com.mycompany.myproject.ReverseProxyVerticle -c conf.json -cp out/production/vert-x-reverse-proxy... same results. It ran as expected but did not pick up changes. Only way to pick up changes was to gradlew clean and re-assemble.
EDIT: I have been through these instructions as well.

For anyone who stumbles upon this question, I had the same problem and managed to fix it by deleting everything under the /mods folder in the /target directory. This is in fact mentioned in the vertx documentation - though maybe could be a little more emphatic. Once everything under /mods is removed, start up the application and it redeploys whenever anything is changed.

If you are new to vertx and stumble with this problem or similar, it might be worth to have a look at this vertx google group entry. It describes the changes that need to be done to the generated project by the Vertx Gradle Template to get it running.
I know, this does not answer directly the question posted here but I hope it helps you further.

javax.xml.parsers.SAXParserFactory ClassCastException

I get on my local machine the following exception when running the tests by maven (mvn test).
ch.qos.logback.core.joran.event.SaxEventRecorder#195ed659 - Parser configuration error occured
java.lang.ClassCastException: com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl cannot be cast to javax.xml.parsers.SAXParserFactory
After googling around I came across several pages which describe the main problem behind it (several SAXParserFactoryImpl in different classloaders).
-> http://www.xinotes.org/notes/note/702/
My question is, how can I figure out which library is also providing the SAXParserFactoryImpl, so that I can exclude it. I am using Maven, IntelliJ and JDK 1.6.0_23. The issue occurs on the command line as well as when running the tests from IntelliJ.
But the strange issue is, that on the build server this issue doesn't occur.
Update 1
Just figured out when I run the first time mvn test after an mvn clean, the error doesn't appear. But as soon as I run mvn test again (without clean, the exception occurs) (when I run it from IntelliJ).
When I run it on the cmd line, then several mvn test calls do work.

I found the issue. It was related to PowerMockito who tried to load the SAXParserFactory. The reason why I haven't figured that one out was because the stacktrace contained only twice PowerMockito, and this at the middle :-)
So If you figure out this problem in IntelliJ and you do use PowerMockito, annotate your test class with the following annotation:
#PowerMockIgnore(["javax.management.*", "javax.xml.parsers.*",
"com.sun.org.apache.xerces.internal.jaxp.*", "ch.qos.logback.*", "org.slf4j.*"])
This has solved the problem in my case.

Your JDK probably has its own SAXParserFactoryImpl.
Check for jars like xercesImpl, xml/xml-api and sax.
One your server the one from the server is probably going to be used.
You can use a jarfinder: http://www.jarfinder.com/index.php/java/search/~SAXParserFactoryImpl~

I encountered the same error today. After a lot of digging, I found that the solutions here, or on other places are not helpful.
However, after playing around, I found a solution that works deterministically, unlike the accepted answer which does not apply to all cases.
The answer is, look through stack trace to find any ClassCast exceptions, and just add them to \#PowerMockIgnore list. Keep repeating until the issue is solved. Worked like magic for me.

Eclipse ClassNotFoundException

Everything works fined, but suddenly eclipse stopped execute and junit tests or even main method, when i run them using run as - > Java application, run as -> junit test
It simply throws error
Caused by: java.lang.ClassNotFoundException: package.ClassName
whene ClassName - is class from where i trying to run method main.
It affect only one of my projects ... Different workspaces works fine, other project in same workspace works fine as well.
I'm sure if i recreate current project, error will gone. But the adjustments of this project in eclipse is really hard, so i want to avoid it.
Any clue?

The ClassName is not in the Class Path, if you start from console you should use -cp parameter , if from eclipse, please add ClassName to the sources of current(start) project.

Thanks to adarshr, I was able to look at the Problems window and determine that the build was failing because it could not find a class I had written.
I had used the MS TFS plugin to create a "shelveset" and it was supposed to have removed my pending changes in the process. However, this integration with the TFS snapin and Eclipse is obviously not well implemented, since the Eclipse project still thought the file existed and was complaining that it could not be compiled.
I went and manually deleted those "files" or "non-existing files" from the Eclipse project (that I thought I had removed with the shelveset action) and the problem was solved.
Also....
Another annoying things is that the Tomcat error I was getting by trying to debug within Eclipse was like this:
SEVERE: Error configuring application listener of class
com.CompanyName.ProjectName.servlet.StartupConfigListener
java.lang.ClassNotFoundException:
com.CompanyName.ProjectName.servlet.StartupConfigListener at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1643)
In reality, there was no problem at all with StartupConfigListener.java!! The build failed due to the OTHER problems I mentioned above, and therefore I guess this was the first class it attempted to load and failed.... because the entire project hadn't been able to compile perhaps?
(Here's to hoping my next project is using Visual Studio instead of Eclipse!)

Ok, I finally figured it out. The problem was with installed JRE in eclipse setting. I was playing around with this setting and changed installed JRE to JDK, and for some reason it broke the eclipse project.

You can also try going back to the basics. Check your command line and VM args. I've had this situation where a VM arg I was passing in was a path to a file that had a space in the path, and I had forgotten to include the full path in quotes. So e.g., if my arg looked something like
-DFILE=C:\Documents and Settings\myfile
...I'd get a java.lang.NoClassDefFoundError caused by a java.lang.ClassNotFoundException.