Java.lang.InstantiationException

Question

My class throws a java.lang.InstantiationException and I can't see why. my class extends an abstract class but should not be abstract itself.
My Class_
package com.propylon.core.tests;
import org.eclipse.core.runtime.Plugin;
import org.osgi.framework.BundleContext;
* The activator class controls the plug-in life cycle
public class Activator extends Plugin {
     // The plug-in ID
     public static final String PLUGIN_ID = "com.propylon.core.tests";
     // The shared instance
     private static Activator plugin;
     * The constructor
     public Activator() {
     * (non-Javadoc)
     * @see org.eclipse.core.runtime.Plugins#start(org.osgi.framework.BundleContext)
     public void start(BundleContext context) throws Exception {
          super.start(context);
          plugin = this;
     * (non-Javadoc)
     * @see org.eclipse.core.runtime.Plugin#stop(org.osgi.framework.BundleContext)
     public void stop(BundleContext context) throws Exception {
          plugin = null;
          super.stop(context);
     * Returns the shared instance
     * @return the shared instance
     public static Activator getDefault() {
          return plugin;
Console Window_
java-test:
[echo] Running com.propylon.core.tests.testcase.AllTests. Result file: C:/eclipse3.3/results/com.propylon.core.tests.testcase.AllTests.xml.
[java] org.osgi.framework.BundleException: The activator org.eclipse.core.runtime.Plugin for bundle com.propylon.core.Test is invalid
[java]      at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadBundleActivator(AbstractBundle.java:141)
[java]      at org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:970)
[java]      at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:346)
[java]      at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:260)
[java]      at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:400)
[java]      at org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:111)
[java]      at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClass(ClasspathManager.java:417)
[java]      at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.findLocalClass(DefaultClassLoader.java:189)
[java]      at org.eclipse.osgi.framework.internal.core.BundleLoader.findLocalClass(BundleLoader.java:340)
[java]      at org.eclipse.osgi.framework.internal.core.BundleLoader.findClassInternal(BundleLoader.java:408)
[java]      at org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:369)
[java]      at org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:357)
[java]      at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:83)
[java]      at java.lang.ClassLoader.loadClass(Unknown Source)
[java]      at org.eclipse.osgi.framework.internal.core.BundleLoader.loadClass(BundleLoader.java:289)
[java]      at org.eclipse.osgi.framework.internal.core.BundleHost.loadClass(BundleHost.java:227)
[java]      at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadClass(AbstractBundle.java:1269)
[java]      at org.eclipse.test.EclipseTestRunner.loadSuiteClass(EclipseTestRunner.java:302)
[java]      at org.eclipse.test.EclipseTestRunner.getTest(EclipseTestRunner.java:233)
[java]      at org.eclipse.test.EclipseTestRunner.<init>(EclipseTestRunner.java:216)
[java]      at org.eclipse.test.EclipseTestRunner.run(EclipseTestRunner.java:200)
[java]      at org.eclipse.test.CoreTestApplication.runTests(CoreTestApplication.java:35)
[java]      at org.eclipse.test.CoreTestApplication.run(CoreTestApplication.java:31)
[java]      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[java]      at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
[java]      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
[java]      at java.lang.reflect.Method.invoke(Unknown Source)
[java]      at org.eclipse.equinox.internal.app.EclipseAppContainer.callMethod(EclipseAppContainer.java:533)
[java]      at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:155)
[java]      at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:106)
[java]      at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:76)
[java]      at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:363)
[java]      at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:176)
[java]      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[java]      at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
[java]      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
[java]      at java.lang.reflect.Method.invoke(Unknown Source)
[java]      at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:504)
[java]      at org.eclipse.equinox.launcher.Main.basicRun(Main.java:443)
[java]      at org.eclipse.equinox.launcher.Main.run(Main.java:1169)
[java]      at org.eclipse.equinox.launcher.Main.main(Main.java:1144)
[java]      at org.eclipse.core.launcher.Main.main(Main.java:30)
[java] Caused by: java.lang.InstantiationException
[java]      at sun.reflect.InstantiationExceptionConstructorAccessorImpl.newInstance(Unknown Source)
[java]      at java.lang.reflect.Constructor.newInstance(Unknown Source)
[java]      at java.lang.Class.newInstance0(Unknown Source)
[java]      at java.lang.Class.newInstance(Unknown Source)
[java]      at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadBundleActivator(AbstractBundle.java:136)
[java]      ... 41 more
[java] Java Result: 2
Is there anything obviously flawed with this class or am I going mad.
thank you for your time
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Answer 1

I can't see anywhere in your code that tries to create an Activator object... i.e. there is nowhere that tries to use the new Activator() constructor, so I would suggest that the problem is not with your code.
This is the description of Instantiation Exception from the API:
Thrown when an application tries to create an instance of a class using the newInstance method in class Class, but the specified class object cannot be instantiated because it is an interface or is an abstract class.
So, I would imagine, somewhere the Class.newInstance() method is being invoked on Plugin (the abstract class) rather than Activator (the non-abstract one)