“需要位置"加载 FXML 文件时出现异常 [英] "Location is required" exception when loading FXML file

问题描述

我正在尝试加载 FXML 文件并将其显示为应用程序窗口，但出现异常.FXML 文件由 FXML Scene Builder 创建.

I am trying to load the FXML file and show it as an application window, but i get an exception. The FXML file was created by the FXML Scene Builder.

这里是课程代码

public class Main extends Application {

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        primaryStage.setScene(FXMLLoader.load(getClass().getResource("sample.fxml")));
        primaryStage.show();
    }
}

和 FXML 文件

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.TitledPane?>
<?import javafx.scene.layout.AnchorPane?>
<TitledPane animated="false" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity"
            prefHeight="400.0" prefWidth="600.0" text="Pass4D" xmlns:fx="http://javafx.com/fxml/1"
            xmlns="http://javafx.com/javafx/8">
    <content>
        <AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="180.0" prefWidth="200.0">
            <children>
                <Button layoutX="211.0" layoutY="134.0" mnemonicParsing="false" prefHeight="33.0" prefWidth="177.0"
                        text="Log in"/>
                <Button layoutX="212.0" layoutY="170.0" mnemonicParsing="false" prefHeight="33.0" prefWidth="175.0"
                        text="Exit"/>
            </children>
        </AnchorPane>
    </content>
</TitledPane>

这是我得到的例外

Exception in Application start method
Exception in thread "main" java.lang.RuntimeException: Exception in Application start method
    at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:875)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$147(LauncherImpl.java:157)
    at com.sun.javafx.application.LauncherImpl$$Lambda$1/2074407503.run(Unknown Source)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException: Location is required.
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3201)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3169)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3142)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3118)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3098)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3091)
    at Pass4D.start(Pass4D.java:19)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$153(LauncherImpl.java:821)
    at com.sun.javafx.application.LauncherImpl$$Lambda$51/317090070.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$166(PlatformImpl.java:323)
    at com.sun.javafx.application.PlatformImpl$$Lambda$47/1833150059.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$null$164(PlatformImpl.java:292)
    at com.sun.javafx.application.PlatformImpl$$Lambda$49/2115863517.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$165(PlatformImpl.java:291)
    at com.sun.javafx.application.PlatformImpl$$Lambda$48/1436737924.run(Unknown Source)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)

我做错了什么?

附言这是项目结构

推荐答案

简短的回答是 getClass().getResource("sample.fxml") 静默返回 null如果在运行时 classpath 上找不到资源，而不是在当前目录等

The short answer is getClass().getResource("sample.fxml") returns null silently if the resource cannot be found on the runtime classpath, not the current directory etc.

所以这取决于您的 IDE 项目设置，如果您使用 eclipse，请尝试添加 sample.fxml 驻留在运行配置中的文件夹.

So this depends on your IDE project setup, if you're using eclipse try adding the folder that sample.fxml resides in the run configuration.

一些想法...

• 尝试 getClass().getResource("/sample.fxml") 代替...
• 尝试将 sample.fxml 移动到资源文件夹中.我对您的 IDE 了解不多，但我怀疑该文件夹仅用于 .java 文件...这对于 eclipse 中的 gradle 项目当然是正确的 - 资源必须在 中>src/main/resources 树作为仅添加到运行时类路径...

• try getClass().getResource("/sample.fxml") instead...
• try moving sample.fxml into the resources folder. I don't know much about your IDE, but I suspect that folder is only used for .java files... this is certainly true for gradle projects in eclipse - resources have to be in the src/main/resources tree as only that is added to the runtime classpath...

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