java - 为什么在尝试运行 JavaFx 应用程序时出现 java.lang.ClassNotFoundException？

Question

我已尝试按照描述创建示例应用程序 here代码是这样的:

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();
    }
}

为什么我得到异常？我使用 NetBeans 7.1 RC1这是屏幕截图。

输出:

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)

这个？

Answer 1

只是根据我在这个屏幕截图中看到的内容粗略猜测:您重命名了应用程序的主类，而 Netbeans 仍在寻找旧的类名来运行它？

尝试右键单击您的项目，然后在弹出的窗口中查看“运行”下的“主类”。

否则，请发布堆栈跟踪本身，而不是它的屏幕截图。