title: Java: IEventBroker null point exception
body: <p>I want to publish an event in my RCP project when I press a JButton. For that I am trying to use the IEventBroker.</p>
  
  <p>I followed the tutorial from vogella.com <a href="http://www.vogella.com/tutorials/Eclipse4EventSystem/article.html#eventsystem_overview" rel="nofollow">here</a>.</p>
  
  <pre><code> @Inject
   private IEventBroker eventBroker; 
  
   @Override
      public void actionPerformed(ActionEvent arg0) {
  
          // THE UPDATE BUTTON
          if (arg0.getSource()== update) {
  
              System.out.println("Button Pressed");
  
              eventBroker.post("test", "New data"); // generates a null point exception
              .....
              .....
  </code></pre>
  
  <p>Unfortunately this generates a null point exception. </p>
  
  <pre><code>Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
  at chipcoach.tableviewerDMA.GanttFrame.actionPerformed(GanttFrame.java:522)
  at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
  at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
  at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
  at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
  at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
  at java.awt.Component.processMouseEvent(Unknown Source)
  at javax.swing.JComponent.processMouseEvent(Unknown Source)
  at java.awt.Component.processEvent(Unknown Source)
  at java.awt.Container.processEvent(Unknown Source)
  at java.awt.Component.dispatchEventImpl(Unknown Source)
  at java.awt.Container.dispatchEventImpl(Unknown Source)
  at java.awt.Component.dispatchEvent(Unknown Source)
  at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
  at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
  at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
  at java.awt.Container.dispatchEventImpl(Unknown Source)
  at java.awt.Window.dispatchEventImpl(Unknown Source)
  at java.awt.Component.dispatchEvent(Unknown Source)
  at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
  at java.awt.EventQueue.access$400(Unknown Source)
  at java.awt.EventQueue$3.run(Unknown Source)
  at java.awt.EventQueue$3.run(Unknown Source)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
  at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
  at java.awt.EventQueue$4.run(Unknown Source)
  at java.awt.EventQueue$4.run(Unknown Source)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
  at java.awt.EventQueue.dispatchEvent(Unknown Source)
  at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
  at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
  at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
  at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
  at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
  at java.awt.EventDispatchThread.run(Unknown Source)
  </code></pre>
  
  <p>In the later part of the tutorial, it also did not state where the @EventTopic and @UIEventTopic annotations are defined.</p>