JavaFx出现错误Caused by: java.lang.NullPointerException: Location is required的解决方法

问题截图：

"C:Program FilesJavajdk1.8.0_131injava.exe" "-javaagent:I:IntelliJ IDEA 2018.2.5libidea_rt.jar=53553:I:IntelliJ IDEA 2018.2.5in" -Dfile.encoding=UTF-8 -classpath "C:Program FilesJavajdk1.8.0_131jrelibcharsets.jar;C:Program FilesJavajdk1.8.0_131jrelibdeploy.jar;C:Program FilesJavajdk1.8.0_131jrelibextaccess-bridge-64.jar;C:Program FilesJavajdk1.8.0_131jrelibextcldrdata.jar;C:Program FilesJavajdk1.8.0_131jrelibextdnsns.jar;C:Program FilesJavajdk1.8.0_131jrelibextjaccess.jar;C:Program FilesJavajdk1.8.0_131jrelibextjfxrt.jar;C:Program FilesJavajdk1.8.0_131jrelibextlocaledata.jar;C:Program FilesJavajdk1.8.0_131jrelibext
ashorn.jar;C:Program FilesJavajdk1.8.0_131jrelibextsunec.jar;C:Program FilesJavajdk1.8.0_131jrelibextsunjce_provider.jar;C:Program FilesJavajdk1.8.0_131jrelibextsunmscapi.jar;C:Program FilesJavajdk1.8.0_131jrelibextsunpkcs11.jar;C:Program FilesJavajdk1.8.0_131jrelibextzipfs.jar;C:Program FilesJavajdk1.8.0_131jrelibjavaws.jar;C:Program FilesJavajdk1.8.0_131jrelibjce.jar;C:Program FilesJavajdk1.8.0_131jrelibjfr.jar;C:Program FilesJavajdk1.8.0_131jrelibjfxswt.jar;C:Program FilesJavajdk1.8.0_131jrelibjsse.jar;C:Program FilesJavajdk1.8.0_131jrelibmanagement-agent.jar;C:Program FilesJavajdk1.8.0_131jrelibplugin.jar;C:Program FilesJavajdk1.8.0_131jrelib
esources.jar;C:Program FilesJavajdk1.8.0_131jrelib
t.jar;Q:JavaProjectJFXTest	argetclasses;Q:mavenmaven_jarcomjfoenixjfoenix8.0.8jfoenix-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$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
	at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
	at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$155(LauncherImpl.java:182)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException: Location is required.
	at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3207)
	at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
	at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
	at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
	at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
	at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
	at sample.Main.start(Main.java:13)
	at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
	at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
	at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
	at java.security.AccessController.doPrivileged(Native Method)
	at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
	at com.sun.glass.ui.InvokeLaterDispatcher$Future.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

 <build>
	<resources>
		
		<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>
</build>