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Eclipse plugin: java.lang.NoClassDefFoundError

Posted by: admin December 28, 2021 Leave a comment


As you can see:

enter image description here

I added jni4net.j- to my referenced libraries but I still receive a java.lang.NoClassDefFoundError Exception:

java.lang.NoClassDefFoundError: net/sf/jni4net/Bridge
    at sibeclipseplugin.debug.DebuggerInterface.initialize(DebuggerInterface.java:15)
    at sibeclipseplugin.debug.SibDebugTarget.<init>(SibDebugTarget.java:65)
    at sibeclipseplugin.ui.launch.LaunchConfigurationDelegate.launch(LaunchConfigurationDelegate.java:30)
    at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:858)
    at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:707)
    at org.eclipse.debug.internal.ui.DebugUIPlugin.buildAndLaunch(DebugUIPlugin.java:1018)
    at org.eclipse.debug.internal.ui.DebugUIPlugin$8.run(DebugUIPlugin.java:1222)
    at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)
Caused by: java.lang.ClassNotFoundException: net.sf.jni4net.Bridge cannot be found by SIBEclipsePlugin_0.0.0.1
    at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:501)
    at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:421)
    at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:412)
    at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    ... 8 more

I have no idea what the problem is. When I start the project as Eclipse-Application it can’t find that class. Running the same code in a normal Java-Project works.

Does anybody know how to fix this?


You need to add the jar files in your build.properties bin.includes entry. Also, in your MANIFEST.MF file, they need to be added in the Runtime->Classpath list (corresponds to the Bundle-ClassPath entry in the MANIFEST.MF).

Edit: if you just put them in the referenced libraries, the OSGi system will not be aware of that fact.


I had exactly the same issue with my .jar in my Referenced Libraries folder (jar was added via right click project –> Build Path –> Configure Build Path –> Libraries –> Add External Jar).

This fixed it: right click project –> Build Path –> Configure Build Path –> Order and Export. Make sure your .jar file is checked. This adds it to the build class path. You’d think this would be automatically checked after first adding the .jar via the above method but it wasn’t.


This may also happen if your jar file is dependent on some other jar files for their woking and you have not added them in your project.


It is not marked to export in the project properties:
“Project Properties” > “Order and Export” tab > make sure the .jar file is checked for export.