title: InvocationTargetException when calling a controllers method - JavaFX
body: <p>I get an InvocationTargetException when I try to call a method from the controller (JavaFX), the code goes as follow:</p>
  
  <pre><code>    public void start(Stage stage) throws Exception {
  
      URL location = getClass().getResource("startScreen.fxml");
      FXMLLoader loader = new FXMLLoader();
  
      loader.setLocation(location);
      loader.setBuilderFactory(new JavaFXBuilderFactory());
  
      //Getting hte controller
      StartScreenController s = (StartScreenController)loader.getController();
  
      //Where error occurs
      s.setParent(this);
  
      Parent root = (Parent) loader.load(location.openStream());
  
      Scene scene = new Scene(root);
      stage.setScene(scene);
      stage.show();
  }
  </code></pre>
  
  <p>It works fine when I remove the "setParent" line.</p>
  
  <p>This seem to have worked for others (as far as from what I have seen when trying to solve this myself).</p>
  
  <p>Any help would be appreciated, thanks. </p>
  
  <p>The error I get (s.setParent is line 38)</p>
  
  <pre><code>    Exception in Application start method
  java.lang.reflect.InvocationTargetException
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:601)
      at com.javafx.main.Main.launchApp(Main.java:642)
      at com.javafx.main.Main.main(Main.java:805)
  Caused by: java.lang.RuntimeException: Exception in Application start method
      at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:403)
      at com.sun.javafx.application.LauncherImpl.access$000(LauncherImpl.java:47)
      at com.sun.javafx.application.LauncherImpl$1.run(LauncherImpl.java:115)
      at java.lang.Thread.run(Thread.java:722)
  Caused by: java.lang.NullPointerException
      at johnsoft.dndcommunication.DndCommunication.start(DndCommunication.java:38)
      at com.sun.javafx.application.LauncherImpl$5.run(LauncherImpl.java:319)
      at com.sun.javafx.application.PlatformImpl$5.run(PlatformImpl.java:206)
      at com.sun.javafx.application.PlatformImpl$4.run(PlatformImpl.java:173)
      at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
      at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29)
      at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:73)
      ... 1 more
  Java Result: 1
  </code></pre>