JAVAFX-加载fxml文件时不设置位置引起的异常

Question

我正在尝试使用以下代码将我的fxml文件集成到我的项目中,

final FXMLLoader fxmlLoader =
            new FXMLLoader(this.getClass().getResource("/sample.fxml"));

Parent root = (Parent) fxmlLoader.load();

程序在第二行崩溃,引发此异常,

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$$Lambda$1/1199823423.run(Unknown Source)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException: Location is required.
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3201)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3169)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3142)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3118)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3098)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3091)
    at FileActions.start(FileActions.java:42)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$153(LauncherImpl.java:821)
    at com.sun.javafx.application.LauncherImpl$$Lambda$51/970544503.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$166(PlatformImpl.java:323)
    at com.sun.javafx.application.PlatformImpl$$Lambda$47/1878510174.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$null$164(PlatformImpl.java:292)
    at com.sun.javafx.application.PlatformImpl$$Lambda$49/1792840102.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$165(PlatformImpl.java:291)
    at com.sun.javafx.application.PlatformImpl$$Lambda$48/1671111378.run(Unknown Source)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)

Process finished with exit code 130

也试过了,

Parent root = FXMLLoader.load(getClass().getResource("../resources/sample.fxml"));
//and
Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));

我不知道这是否相关，但这是我的iml文件，

    <?xml version="1.0" encoding="UTF-8"?>
<module org.jetbrains.idea.maven.project.MavenProjectsManager.isMavenModule="true" type="JAVA_MODULE" version="4">
  <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_1_6" inherit-compiler-output="false">
    <output url="file://$MODULE_DIR$/target/classes" />
    <output-test url="file://$MODULE_DIR$/target/test-classes" />
    <content url="file://$MODULE_DIR$">
      <sourceFolder url="file://$MODULE_DIR$/src/main/java" isTestSource="false" />
      <sourceFolder url="file://$MODULE_DIR$/src/main/resources" type="java-resource" />
      <sourceFolder url="file://$MODULE_DIR$/src/test/java" isTestSource="true" />
      <sourceFolder url="file://$MODULE_DIR$" isTestSource="false" />
      <excludeFolder url="file://$MODULE_DIR$/target" />
    </content>
    <orderEntry type="jdk" jdkName="1.8" jdkType="JavaSDK" />
    <orderEntry type="sourceFolder" forTests="false" />
    <orderEntry type="module-library" scope="TEST">
      <library name="JUnit4">
        <CLASSES>
          <root url="jar://$APPLICATION_HOME_DIR$/lib/junit-4.12.jar!/" />
          <root url="jar://$APPLICATION_HOME_DIR$/lib/hamcrest-core-1.3.jar!/" />
        </CLASSES>
        <JAVADOC />
        <SOURCES />
      </library>
    </orderEntry>
    <orderEntry type="library" exported="" name="commons-net-3.6" level="project" />
    <orderEntry type="library" exported="" name="hamcrest-core-1.3" level="project" />
    <orderEntry type="library" exported="" name="junit-4.12" level="project" />
  </component>
</module>

是什么原因造成的？我该如何修复它？

这里是我的项目的一个拉链，如果有人想看一下。

谢谢,

亨利

Answer 1

我看到你在使用maven和Jetbrains。当fxml文件在代码中的位置错误时，确实会出现这种异常。您正在使用Maven。Maven正在它的resources文件夹中搜索资源（如fxml文件）。maven项目的根文件夹就是pom.xml所在的地方。我将其引用为{mavenRoot}。假设您的fxml文件位于以下路径：

{mavenRoot}/src/main/resources/fxml/sample.fxml

然后可以使用以下两行设置fxml加载器：

FXMLLoader loader1 = new FXMLLoader();
loader1.setLocation(getClass().getResource("/fxml/sample.fxml"));

在maven项目中，getResource()将搜索{mavenRoot}/src/main/resources文件夹。