title: Why do I have java.lang.ClassNotFoundException while trying to run JavaFx application?
body: <p>I have tried to create example application as described <a href="http://docs.oracle.com/javafx/2.0/get_started/ColorfulCircles.java.html" rel="nofollow noreferrer">here</a> and the code is this:</p>
  
  <pre><code>package colorfulcircles;
  
  import javafx.animation.KeyFrame;
  import javafx.animation.KeyValue;
  import javafx.animation.Timeline;
  import javafx.application.Application;
  import javafx.scene.Group;
  import javafx.scene.Node;
  import javafx.scene.Scene;
  import javafx.scene.effect.BlendMode;
  import javafx.scene.effect.BoxBlur;
  import javafx.scene.paint.Color;
  import javafx.scene.paint.CycleMethod;
  import javafx.scene.paint.LinearGradient;
  import javafx.scene.paint.Stop;
  import javafx.scene.shape.Circle;
  import javafx.scene.shape.Rectangle;
  import javafx.scene.shape.StrokeType;
  import javafx.stage.Stage;
  import javafx.util.Duration;
  import static java.lang.Math.random;
  
  
  public class ColorfulCircles extends Application {
  
      public static void main(String[] args) {
          launch(args);
      }
  
      @Override
      public void start(Stage primaryStage) {
          Group root = new Group();
          Scene scene = new Scene(root, 800, 600, Color.BLACK);
          primaryStage.setScene(scene);
          Group circles = new Group();
          for (int i = 0; i &lt; 30; i++) {
              Circle circle = new Circle(150, Color.web("white", 0.05));
              circle.setStrokeType(StrokeType.OUTSIDE);
              circle.setStroke(Color.web("white", 0.16));
              circle.setStrokeWidth(4);
              circles.getChildren().add(circle);
          }
          Rectangle colors = new Rectangle(scene.getWidth(), scene.getHeight(),
                  new LinearGradient(0f, 1f, 1f, 0f, true, CycleMethod.NO_CYCLE, new Stop[]{
                      new Stop(0, Color.web("#f8bd55")),
                      new Stop(0.14, Color.web("#c0fe56")),
                      new Stop(0.28, Color.web("#5dfbc1")),
                      new Stop(0.43, Color.web("#64c2f8")),
                      new Stop(0.57, Color.web("#be4af7")),
                      new Stop(0.71, Color.web("#ed5fc2")),
                      new Stop(0.85, Color.web("#ef504c")),
                      new Stop(1, Color.web("#f2660f")),}));
          Group blendModeGroup =
                  new Group(new Group(new Rectangle(scene.getWidth(), scene.getHeight(),
                       Color.BLACK), circles), colors);
          colors.setBlendMode(BlendMode.OVERLAY);
          root.getChildren().add(blendModeGroup);      
          circles.setEffect(new BoxBlur(10, 10, 3));
          Timeline timeline = new Timeline();
          for (Node circle : circles.getChildren()) {
              timeline.getKeyFrames().addAll(
                      new KeyFrame(Duration.ZERO, // set start position at 0
                      new KeyValue(circle.translateXProperty(), random() * 800),
                      new KeyValue(circle.translateYProperty(), random() * 600)),
                      new KeyFrame(new Duration(40000), // set end position at 40s
                      new KeyValue(circle.translateXProperty(), random() * 800),
                      new KeyValue(circle.translateYProperty(), random() * 600)));
          }
          // play 40s of animation
          timeline.play();
          primaryStage.show();
      }
  }
  </code></pre>
  
  <p>Why am I getting Exception?
  I use NetBeans 7.1 RC1
  Here is the screenshot.</p>
  
  <p><img src="https://i.stack.imgur.com/pjhMG.jpg" alt="enter image description here"></p>
  
  <p>Output:</p>
  
  <pre><code>java.lang.ClassNotFoundException: javafxapplication4.JavaFXApplication4
      at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
      at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
      at java.lang.Class.forName0(Native Method)
      at java.lang.Class.forName(Class.java:264)
      at com.javafx.main.Main.getAppClass(Main.java:409)
      at com.javafx.main.Main.launchApp(Main.java:435)
      at com.javafx.main.Main.main(Main.java:537)
  </code></pre>
  
  <p>This one?</p>