Why do I have java.lang.ClassNotFoundException while trying to run JavaFx application?

问题

I have tried to create example application as described here and the code is this:

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 < 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();
    }
}

Why am I getting Exception? I use NetBeans 7.1 RC1 Here is the screenshot.

Output:

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)

This one?

回答1:

Just a wild guess based on what I can see in this screen shot: You renamed the main class of your application and Netbeans is still looking for the old class name to run it?

Try right clicking your project, and looking at the "Main Class" under "Run" in the window that pops up.

Otherwise, please post the stack trace itself, not a screen shot of it.

来源：https://stackoverflow.com/questions/8513651/why-do-i-have-java-lang-classnotfoundexception-while-trying-to-run-javafx-applic