title: getting java.lang.reflect.InvocationTargetException while adding a button to layout
body: <p>I am totally new in javafx!!
  I tried a very very simple code and I got stuck.
  when I tried to add a button to the layout It does not work.
  I know this question may be too simple but I really do not know how to fix it.
  I would appreciated if you could help me.
  This is my code:</p>
  
  <pre><code>import javafx.application.Application;
  import javafx.scene.Scene;
  import javafx.scene.control.Button;
  import javafx.scene.layout.StackPane;
  import javafx.stage.Stage;
  
  
  public class Test extends Application{
  
      Button button;
  
      public static void main(String[] args){
          launch(args);
      }
  
      @Override
      public void start(Stage stage) throws Exception {
          stage.setTitle("Title");
          StackPane layout = new StackPane();
  
          button = new Button();
          layout.getChildren().add(button);
          Scene scene = new Scene(layout);
          stage.setScene(scene);
          stage.show();
      }
  }
  </code></pre>
  
  <p>and I got the error:</p>
  
  <pre><code>Exception in Application start method
  java.lang.reflect.InvocationTargetException
      at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.base/java.lang.reflect.Method.invoke(Method.java:566)
      at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:464)
      at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:363)
      at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.base/java.lang.reflect.Method.invoke(Method.java:566)
      at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1051)
  Caused by: java.lang.RuntimeException: Exception in Application start method
      at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:900)
      at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:195)
      at java.base/java.lang.Thread.run(Thread.java:834)
  Caused by: java.lang.IllegalAccessError: superclass access check failed: class com.sun.javafx.scene.control.ControlHelper (in unnamed module @0x46b3f4cf) cannot access class com.sun.javafx.scene.layout.RegionHelper (in module javafx.graphics) because module javafx.graphics does not export com.sun.javafx.scene.layout to unnamed module @0x46b3f4cf
      at java.base/java.lang.ClassLoader.defineClass1(Native Method)
      at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
      at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
      at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:802)
      at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:700)
      at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:623)
      at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
      at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
      at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
      at javafx.scene.control.Control.&lt;clinit&gt;(Control.java:86)
      at Test.start(Test.java:21)
      at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:846)
      at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:455)
      at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:428)
      at java.base/java.security.AccessController.doPrivileged(Native Method)
      at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:427)
      at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
      at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
      at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
      ... 1 more
  Exception running application Test
  </code></pre>