JavaFX NullPointerException位置是必需的NetBeans

Question

我已经尝试了我在堆栈stackoverflow上找到的任何其他东西,我真的不明白为什么这不起作用.我不会向您展示我的应用程序的代码无法正常工作,因为它甚至不能用于示例项目.所以这是问题所在:

当我使用示例代码创建新的JavaFX应用程序时,该代码提供了单击后打印hello world的按钮,当我将其作为桌面应用程序运行时以及当我构建它并在浏览器中启动时,这将起作用.这适用于桌面和浏览器应用程序

但是当我创建新的JavaFX FXML应用程序时,它几乎与上面相同,但阶段由fxml和css定义,而不是字节代码.这个作为Windows应用程序完美地工作,但不能作为浏览器应用程序

java.lang.NullPointerException: Location is required.
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.load(Unknown Source)
    at javafxapplication3.JavaFXApplication3.start(JavaFXApplication3.java:22)
    at com.sun.javafx.applet.FXApplet2$2.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$null$170(Unknown Source)
    at com.sun.javafx.application.PlatformImpl$$Lambda$46/15592694.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$171(Unknown Source)
    at com.sun.javafx.application.PlatformImpl$$Lambda$45/19532686.run(Unknown Source)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(Unknown Source)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$145(Unknown Source)
    at com.sun.glass.ui.win.WinApplication$$Lambda$35/9825943.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.NullPointerException: Location is required.
    at com.sun.javafx.applet.FXApplet2$2.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$null$170(Unknown Source)
    at com.sun.javafx.application.PlatformImpl$$Lambda$46/15592694.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$171(Unknown Source)
    at com.sun.javafx.application.PlatformImpl$$Lambda$45/19532686.run(Unknown Source)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(Unknown Source)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$145(Unknown Source)
    at com.sun.glass.ui.win.WinApplication$$Lambda$35/9825943.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException: Location is required.
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.load(Unknown Source)
    at javafxapplication3.JavaFXApplication3.start(JavaFXApplication3.java:22)
    ... 11 more

这是工作申请的代码:

public class JavaFXApplication4 extends Application {

    @Override
    public void start(Stage primaryStage) {
        Button btn = new Button();
        btn.setText("Say 'Hello World'");
        btn.setOnAction(new EventHandler<ActionEvent>() {

            @Override
            public void handle(ActionEvent event) {
                System.out.println("Hello World!");
            }
        });

        StackPane root = new StackPane();
        root.getChildren().add(btn);

        Scene scene = new Scene(root, 300, 250);

        primaryStage.setTitle("Hello World!");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }

并且此应用程序在浏览器中不起作用并抛出异常:

public class JavaFXApplication3 extends Application {

    @Override
    public void start(Stage stage) throws Exception {
        Parent root = FXMLLoader.load(getClass().getResource("FXMLDocument.fxml"));

        Scene scene = new Scene(root);

        stage.setScene(scene);
        stage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }

}

有人能帮我吗？

Answer 1

问题出在这一行:

Parent root = FXMLLoader.load(getClass().getResource("FXMLDocument.fxml"));

很明显,load方法实际上是使用null参数调用的.这是因为getResource("/ sample/sample.fxml")无法归档该资源.

运行时类路径上缺少资源(或路径错误).

资源