title: Class not getting injected in IEclipseContext
body: <p>As I am new to Eclipse-RCP I was doing an exercise from a book. Below is the problem I am facing while doing the exercise</p>
  
  <p>I have a class called "SnippetRepository" in my Eclipse E4 project</p>
  
  <pre><code>public class SnippetRepository {
  
      public ArrayList&lt;SnippetData&gt; snippets = new ArrayList&lt;&gt;();
      public String repositoryPath;
  
      public SnippetRepository() {
          super();
          // TODO Auto-generated constructor stub
      }
  }
  </code></pre>
  
  <p>I am trying to create a custom event and a handler which uses the above class</p>
  
  <pre><code>public class SnippetListView {
          ......
      ............
         @Inject
      public void onAddNewSnippet(@Optional @UIEventTopic(CodeSnippetAppConstants.NEW_SNIPPET_EVENT) Object data,
              SnippetRepository repository) {
          SnippetData newSnippet = new SnippetData("Untitled" + (newSnippetCounter++));
          repository.snippets.add(newSnippet);
          snippetview.refresh();
          snippetview.setSelection(new StructuredSelection(newSnippet));
  
      }
  
  }
  </code></pre>
  
  <p>The above method generates a null pointer exception as "SnippetRepository" class is not getting injected in context</p>
  
  <p>I have included an object of "SnippetRepository" class in Activator class</p>
  
  <pre><code>@Override
      public void start(BundleContext context) throws Exception {
          // TODO Auto-generated method stub
          IEclipseContext ctx = E4Workbench.getServiceContext();
          SnippetRepository repository = new SnippetRepository();
          ctx.set(SnippetRepository.class, repository);
  
      }
  </code></pre>
  
  <p>This is the stacktrace I am getting</p>
  
  <pre class="lang-none prettyprint-override"><code>org.eclipse.e4.core.di.InjectionException: Unable to process "SnippetListView#onAddNewSnippet()": no actual value was found for the argument "SnippetRepository".
      at org.eclipse.e4.core.internal.di.InjectorImpl.reportUnresolvedArgument(InjectorImpl.java:424)
      at org.eclipse.e4.core.internal.di.InjectorImpl.resolveRequestorArgs(InjectorImpl.java:415)
      at org.eclipse.e4.core.internal.di.InjectorImpl.inject(InjectorImpl.java:110)
      at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:345)
      at org.eclipse.e4.core.internal.di.InjectorImpl.make(InjectorImpl.java:264)
      at org.eclipse.e4.core.contexts.ContextInjectionFactory.make(ContextInjectionFactory.java:162)
      at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.createFromBundle(ReflectionContributionFactory.java:104)
      at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.doCreate(ReflectionContributionFactory.java:73)
      at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.create(ReflectionContributionFactory.java:55)
      at org.eclipse.e4.ui.workbench.renderers.swt.ContributedPartRenderer.createWidget(ContributedPartRenderer.java:129)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createWidget(PartRenderingEngine.java:971)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:640)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:746)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$0(PartRenderingEngine.java:717)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:711)
      at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:695)
      at org.eclipse.e4.ui.workbench.renderers.swt.SWTPartRenderer.processContents(SWTPartRenderer.java:71)
      at org.eclipse.e4.ui.workbench.renderers.swt.SashRenderer.processContents(SashRenderer.java:151)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:654)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:746)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$0(PartRenderingEngine.java:717)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:711)
      at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:695)
      at org.eclipse.e4.ui.workbench.renderers.swt.SWTPartRenderer.processContents(SWTPartRenderer.java:71)
      at org.eclipse.e4.ui.workbench.renderers.swt.PerspectiveRenderer.processContents(PerspectiveRenderer.java:49)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:654)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:746)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$0(PartRenderingEngine.java:717)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:711)
      at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:695)
      at org.eclipse.e4.ui.workbench.renderers.swt.PerspectiveStackRenderer.showTab(PerspectiveStackRenderer.java:82)
      at org.eclipse.e4.ui.workbench.renderers.swt.LazyStackRenderer$1.handleEvent(LazyStackRenderer.java:72)
      at org.eclipse.e4.ui.services.internal.events.UIEventHandler$1.run(UIEventHandler.java:40)
      at org.eclipse.swt.widgets.Synchronizer.syncExec(Synchronizer.java:186)
      at org.eclipse.swt.widgets.Display.syncExec(Display.java:4761)
      at org.eclipse.e4.ui.internal.workbench.swt.E4Application$1.syncExec(E4Application.java:211)
      at org.eclipse.e4.ui.services.internal.events.UIEventHandler.handleEvent(UIEventHandler.java:36)
      at org.eclipse.equinox.internal.event.EventHandlerWrapper.handleEvent(EventHandlerWrapper.java:197)
      at org.eclipse.equinox.internal.event.EventHandlerTracker.dispatchEvent(EventHandlerTracker.java:197)
      at org.eclipse.equinox.internal.event.EventHandlerTracker.dispatchEvent(EventHandlerTracker.java:1)
      at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
      at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:148)
      at org.eclipse.equinox.internal.event.EventAdminImpl.dispatchEvent(EventAdminImpl.java:135)
      at org.eclipse.equinox.internal.event.EventAdminImpl.sendEvent(EventAdminImpl.java:78)
      at org.eclipse.equinox.internal.event.EventComponent.sendEvent(EventComponent.java:39)
      at org.eclipse.e4.ui.services.internal.events.EventBroker.send(EventBroker.java:85)
      at org.eclipse.e4.ui.internal.workbench.UIEventPublisher.notifyChanged(UIEventPublisher.java:59)
      at org.eclipse.emf.common.notify.impl.BasicNotifierImpl.eNotify(BasicNotifierImpl.java:374)
      at org.eclipse.e4.ui.model.application.ui.advanced.impl.PerspectiveStackImpl.setSelectedElement(PerspectiveStackImpl.java:135)
      at org.eclipse.e4.ui.model.application.ui.advanced.impl.PerspectiveStackImpl.setSelectedElement(PerspectiveStackImpl.java:1)
      at org.eclipse.e4.ui.workbench.renderers.swt.LazyStackRenderer.postProcess(LazyStackRenderer.java:108)
      at org.eclipse.e4.ui.workbench.renderers.swt.PerspectiveStackRenderer.postProcess(PerspectiveStackRenderer.java:63)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:658)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:746)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$0(PartRenderingEngine.java:717)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:711)
      at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:695)
      at org.eclipse.e4.ui.workbench.renderers.swt.SWTPartRenderer.processContents(SWTPartRenderer.java:71)
      at org.eclipse.e4.ui.workbench.renderers.swt.WBWRenderer.processContents(WBWRenderer.java:614)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:654)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:746)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$0(PartRenderingEngine.java:717)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:711)
      at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:695)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$4.run(PartRenderingEngine.java:1057)
      at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:337)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1018)
      at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:156)
      at org.eclipse.e4.ui.internal.workbench.swt.E4Application.start(E4Application.java:159)
      at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
      at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
      at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
      at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:380)
      at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:235)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
      at java.lang.reflect.Method.invoke(Unknown Source)
      at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:669)
      at org.eclipse.equinox.launcher.Main.basicRun(Main.java:608)
      at org.eclipse.equinox.launcher.Main.run(Main.java:1515)
      at org.eclipse.equinox.launcher.Main.main(Main.java:1488)
  </code></pre>