Netbeans中的java JavaFX项目引发异常“输入流不能为null”

1 月，1 周 Questions & Answers 63

你好
我正在Windows 10和JDK 14上使用Netbeans 12.0。我正试图从Oracle文档中构建一个JavaFX代码示例：

https://docs.oracle.com/javafx/2/ui_controls/slider.htm

在IDE中运行应用程序时，我遇到一个运行时错误“输入流不能为null”。问题主要发生在它试图从图像对象创建图像对象时。jpg文件，该文件导致空流，从而导致空指针异常。我在StackOverflow中看到过类似的问题，其共同点是指向资源文件（即png或jpg文件）的路径不正确。为了避免这个问题，每次构建之后，我都会手动复制我的。jpg到target/classes/${package}子文件夹，所有构建类都驻留在该子文件夹中，我仍然收到一个NullPointer异常

以下是根据堆栈跟踪导致异常的主线（第33行）的摘录：

final Image image = new Image(ProgressSilder.class.getResourceAsStream("C://Temp//cappuccino.jpg"));

异常堆栈跟踪：

Exception in Application constructor java.lang.reflect.InvocationTargetException at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:564) at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:464) at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:363) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:564) at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1051) Caused by: java.lang.RuntimeException: Unable to construct Application instance: class org.openjfx.mavenfxprogressslider.ProgressSilder at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:890) at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:195) at java.base/java.lang.Thread.run(Thread.java:832) Caused by: java.lang.reflect.InvocationTargetException at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500) at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481) at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$8(LauncherImpl.java:802) at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:455) at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:428) at java.base/java.security.AccessController.doPrivileged(AccessController.java:391) at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:427) at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96) at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method) at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174) ... 1 more Caused by: java.lang.NullPointerException: Input stream must not be null at javafx.graphics/javafx.scene.image.Image.validateInputStream(Image.java:1135) at javafx.graphics/javafx.scene.image.Image.<init>(Image.java:702) at org.openjfx.mavenfxprogressslider/org.openjfx.mavenfxprogressslider.ProgressSilder.<init>(ProgressSilder.java:33) ... 14 more Exception running application org.openjfx.mavenfxprogressslider.ProgressSilder Command execution failed. org.apache.commons.exec.ExecuteException: Process exited with an error: 1 (Exit value: 1) at org.apache.commons.exec.DefaultExecutor.executeInternal (DefaultExecutor.java:404) at org.apache.commons.exec.DefaultExecutor.execute (DefaultExecutor.java:166) at org.openjfx.JavaFXBaseMojo.executeCommandLine (JavaFXBaseMojo.java:504) at org.openjfx.JavaFXBaseMojo.executeCommandLine (JavaFXBaseMojo.java:394) at org.openjfx.JavaFXRunMojo.execute (JavaFXRunMojo.java:100) at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137) at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210) at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156) at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81) at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56) at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128) at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305) at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192) at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105) at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957) at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289) at org.apache.maven.cli.MavenCli.main (MavenCli.java:193) at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method) at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62) at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke (Method.java:564) at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282) at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225) at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406) at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347) org.apache.commons.exec.ExecuteException: Process exited with an error: 1 (Exit value: 1) at org.apache.commons.exec.DefaultExecutor.executeInternal(DefaultExecutor.java:404) at org.apache.commons.exec.DefaultExecutor.execute(DefaultExecutor.java:166) at org.openjfx.JavaFXBaseMojo.executeCommandLine(JavaFXBaseMojo.java:504) at org.openjfx.JavaFXBaseMojo.executeCommandLine(JavaFXBaseMojo.java:394) at org.openjfx.JavaFXRunMojo.execute(JavaFXRunMojo.java:100) at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:137) at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:210) at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:156) at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:148) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:117) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81) at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:56) at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128) at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305) at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192) at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105) at org.apache.maven.cli.MavenCli.execute(MavenCli.java:957) at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:289) at org.apache.maven.cli.MavenCli.main(MavenCli.java:193) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:564) at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282) at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225) at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406) at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)

你知道如何避免这个错误吗
谢谢

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Netbeans中的java JavaFX项目引发异常“输入流不能为null”

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