问题截图：
“C:\Program Files\Java\jdk1.8.0_131\bin\java.exe” “-javaagent:I:\IntelliJ IDEA 2018.2.5\lib\idea_rt.jar=53553:I:\IntelliJ IDEA 2018.2.5\bin” -Dfile.encoding=UTF-8 -classpath “C:\Program Files\Java\jdk1.8.0_131\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\rt.jar;Q:\JavaProject\JFXTest\target\classes;Q:\maven\maven_jar\com\jfoenix\jfoenix\8.0.8\jfoenix-8.0.8.jar” sample.Main
Exception in Application start method
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.launcher.LauncherHelper
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FXHelper.main(LauncherHelper.java:767) Caused by: java.lang.RuntimeException: Exception in Application start method at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917) at com.sun.javafx.application.LauncherImpl.lambda
FXHelper.main(LauncherHelper.java:767)Causedby:java.lang.RuntimeException:ExceptioninApplicationstartmethodatcom.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)atcom.sun.javafx.application.LauncherImpl.lambdalaunchApplication
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155(LauncherImpl.java:182) at java.lang.Thread.run(Thread.java:748) Caused by: java.lang.NullPointerException: Location is required. at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3207) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104) at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097) at sample.Main.start(Main.java:13) at com.sun.javafx.application.LauncherImpl.lambda
155(LauncherImpl.java:182)atjava.lang.Thread.run(Thread.java:748)Causedby:java.lang.NullPointerException:Locationisrequired.atjavafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3207)atjavafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)atjavafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)atjavafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)atjavafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)atjavafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)atsample.Main.start(Main.java:13)atcom.sun.javafx.application.LauncherImpl.lambdalaunchApplication1
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162(LauncherImpl.java:863) at com.sun.javafx.application.PlatformImpl.lambda
162(LauncherImpl.java:863)atcom.sun.javafx.application.PlatformImpl.lambdarunAndWait
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175(PlatformImpl.java:326) at com.sun.javafx.application.PlatformImpl.lambda
175(PlatformImpl.java:326)atcom.sun.javafx.application.PlatformImpl.lambdanull
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173(PlatformImpl.java:295) at java.security.AccessController.doPrivileged(Native Method) at com.sun.javafx.application.PlatformImpl.lambda
173(PlatformImpl.java:295)atjava.security.AccessController.doPrivileged(NativeMethod)atcom.sun.javafx.application.PlatformImpl.lambdarunLater
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174(PlatformImpl.java:294) at com.sun.glass.ui.InvokeLaterDispatcher
174(PlatformImpl.java:294)atcom.sun.glass.ui.InvokeLaterDispatcherFuture.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
… 1 more
Exception running application sample.Main
Process finished with exit code 1
问题原因
问题出现的原因是因为空指针，也就是getClass().getResource(“sample.fxml”)这个方法的结果为空
我们可以测试一下，把代码稍微分为两段
如图，如果为空，则输出hello，停止程序
测试结果如下图
分析
上面我们知道了，没有找到该文件，那么，我们把那个fxml布局放在该目录下就可以解决空指针的问题了。
我们先看看改路径是在哪里（使用getResource("")）
结果为
然后我查一下了Maven，因为我们使用了Maven，它会把java文件编译成的class文件默认放在一个名为target的文件夹中.其他的文件就会忽略，不放在target文件夹中
解决方法
解决办法很简单，我们只需要在pom.xml设置，将布局fxml文件放在target文件夹中即可
<resource>
<!-- 这里是放在 src/main/java-->
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.fxml</include>
<include>**/fxml/*.fxml</include>
<!-- 如果想要弄个包名专门放fxml文件，像上一行这样添加设置 -->
<!-- 之后，使用getResource("fxml/xx.fxml")这样子 -->
</includes>
<filtering>false</filtering>
</resource>
</resources>
