2 Replies Latest reply: Mar 20, 2013 2:39 AM by gimbal2 RSS

    Class being found by classloader but NoClassDefFoundError on newInstance()

      Hello Friends,<br>
      I have an junit testcase that tests a eclipse application with a very long classpath and this can't be executed in Eclipse because of Windows classpath limitations. So I decided to write a program that will execute the the JUnit Test. I create my own classloader that takes the long classpath as url and then from the classpath create "org.junit.runner.JUnitCore" and create a new instance from this class. I can load the class without any problem but as soon as I try to instantiate an object of this class I get a NoClassDefFoundError. Here is the code:

      package test.com.ebay.app.rtm.biz;

           import java.io.File;
           import java.net.MalformedURLException;
           import java.net.URL;
           import java.net.URLClassLoader;
           import java.util.ArrayList;
           import java.util.List;

           public class RunJUnitTests {
                private String classPath = "C:\\Unzips\\jmockit-1.1\\jmockit\\jmockit.jar;C:\\maven.repo\\sasurendran\\ebox\\junit\\junit\\4.11\\junit-4.11.jar;... Very long classpath";
                * @param args
                public static void main(String[] args) {
                     RunJUnitTests runJUnitTests = new RunJUnitTests();
                private void doWork() {
                     URLClassLoader ucl = new URLClassLoader(getClassPathAsURLs(classPath));
                     System.out.println("UCL:" + ucl.toString());
                     JUnitThread runJUnitTests = new JUnitThread(ucl);
                     Thread t = new Thread(runJUnitTests);
                private void printClassPath(URL[] urls){
                     for(URL url:urls)
                public URL[] getClassPathAsURLs(String classpath) {
                     List<URL> urlList = new ArrayList<URL>();
                for(String path : classpath.split(";")){
                try {
                     urlList.add(new File(path).toURI().toURL());
                } catch (MalformedURLException e) {
                     // TODO Auto-generated catch block
                return urlList.toArray(new URL[]{});


      This is the thread class which uses the custom class loader I created:

      package test.com.ebay.app.rtm.biz;

           import java.net.URLClassLoader;

           import org.junit.runner.JUnitCore;
           import org.junit.runner.Result;
           import org.junit.runner.notification.Failure;

           public class JUnitThread implements Runnable {
                URLClassLoader ucl;
                public JUnitThread(URLClassLoader cl){
                     ucl = cl;

                public void run() {
                     try {
                          Class<JUnitCore> clz = (Class<JUnitCore>) ucl.loadClass("org.junit.runner.JUnitCore");
                          System.out.println("Loaded class : " + clz.getName());
                          //Object obj = clz.newInstance();
                          //JUnitCore junit = (JUnitCore)obj;
                          JUnitCore junit = clz.newInstance();
                          System.out.println("Thread CL:" + Thread.currentThread().getContextClassLoader().toString());
                          Result result = junit.runClasses(RtmCampaignSelectorTest.class);
                     for (Failure failure : result.getFailures()) {
                     } catch (InstantiationException e) {
                          // TODO Auto-generated catch block
                     } catch (IllegalAccessException e) {
                          // TODO Auto-generated catch block
                     } catch (ClassNotFoundException e) {



      Output of the code:

      Loaded class : org.junit.runner.JUnitCore<br>
      Exception in thread "Thread-0" java.lang.NoClassDefFoundError: org/junit/runner/JUnitCore
           at test.com.ebay.app.rtm.biz.JUnitThread.run(JUnitThread.java:25)
           at java.lang.Thread.run(Thread.java:662)
      Caused by: java.lang.ClassNotFoundException: org.junit.runner.JUnitCore
           at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
           at java.security.AccessController.doPrivileged(Native Method)
           at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
           at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
           at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
           at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
           ... 2 more

      As you can see the ClassLoader is able to find the class but not able to instantiate it from jar file 'jar:file:/C:/maven.repo/sasurendran/ebox/junit/junit/4.11/junit-4.11.jar' but not able to create a newInstance of it. Could you please help me?