JavaFX在打包后为图像抛出错误

我有一个JavaFX应用程序，它在IntelliJ中运行得非常好。但是如果我创建一个工件并构建它，我会得到一个

java.lang.NullPointerException

，因为它找不到特定的图像。下面是我收到的错误消息：

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
        at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1787)
        at javafx.fxml/javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1670)
        at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
        at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
        at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
        at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
        at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
        at javafx.base/javafx.event.Event.fireEvent(Event.java:198)
        at javafx.graphics/javafx.scene.Node.fireEvent(Node.java:8879)
        at javafx.controls/javafx.scene.control.Button.fire(Button.java:200)
        at javafx.controls/com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:206)
        at javafx.controls/com.sun.javafx.scene.control.inputmap.InputMap.handle(InputMap.java:274)
        at javafx.base/com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
        at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
        at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
        at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
        at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
        at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
        at javafx.base/javafx.event.Event.fireEvent(Event.java:198)
        at javafx.graphics/javafx.scene.Scene$MouseHandler.process(Scene.java:3851)
        at javafx.graphics/javafx.scene.Scene$MouseHandler.access$1200(Scene.java:3579)
        at javafx.graphics/javafx.scene.Scene.processMouseEvent(Scene.java:1849)
        at javafx.graphics/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2588)
        at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:397)
        at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
        at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
        at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:434)
        at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:390)
        at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:433)
        at javafx.graphics/com.sun.glass.ui.View.handleMouseEvent(View.java:556)
        at javafx.graphics/com.sun.glass.ui.View.notifyMouse(View.java:942)
        at javafx.graphics/com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
        at javafx.graphics/com.sun.glass.ui.gtk.GtkApplication.lambda$runLoop$11(GtkApplication.java:277)
        at java.base/java.lang.Thread.run(Thread.java:830)
Caused by: java.lang.reflect.InvocationTargetException
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:567)
        at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:76)
        at jdk.internal.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:567)
        at javafx.base/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:273)
        at javafx.fxml/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:83)
        at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1784)
        ... 63 more
Caused by: java.lang.NullPointerException
        at gui.EditItem.generateLabel(EditItem.java:109)
        at gui.EditItem.lambda$start$1(EditItem.java:66)
        at java.base/java.lang.Iterable.forEach(Iterable.java:75)
        at gui.EditItem.start(EditItem.java:65)
        at gui.Scene.launch(Scene.java:45)
        at gui.Item.editEntry(Item.java:88)
        ... 74 more

我知道错误是由于这一行（第109行）引起的，因为删除它可以解决问题：

ImageView closeIcon=newimageview（新图像（getClass（）.getResource（“../assets/baseline\u close\u black\u 18dp.png”）.toString（））

我想知道是否有人知道我为什么会出现这个错误，因为如果它在IntelliJ内部工作，那么它应该在打包后工作。感谢您的帮助。谢谢。
我希望这能解决你的问题

在intellij内部运行时，您是从系统路径访问映像的，因为映像存在于系统中，当您打包时（比如对jar），您将无法使用系统路径访问映像

因此，请确保您的图像与您正在构建的工件打包在一起，并且您需要修改代码以返回
inputStream
，因为
文件
api在这种情况下变得无用，这有望实现以下目的：

ClassLoader ClassLoader=getClass（）.getClassLoader（）；
试一试{
InputStream in=classLoader.getResourceAsStream（“/assets/baseline\u close\u black\u 18dp.png”）；
图像=新图像（英寸）；
ImageView ImageView=新的ImageView（图像）；
}捕获（例外情况除外）{
}

问候

一些支持我答案的参考资料：



对于稍后查看此内容的任何人，正如fabian所建议的，另一个选项是使用
新图像（getClass（）.getResource（“/assets/baseline\u close\u black\u 18dp.png”）.toExternalForm（）
它将使用
从
src/assets/baseline\u close\u black\u 18dp.png
获取图像。
不受
getResource
API支持。好的，我认为这就是问题所在。因此，除了下面@thechaoticpanda解释的方法之外，没有其他方法可以进入目录获取资产了吗？正确的路径从类路径根开始，并有一个前导的
/
，在您的例子中，这看起来确实是
/assets/…
。但有一件事让我抓狂，那就是他们对类加载器的使用。类加载器的路径通常不以前导的
/
开头。不过，我建议不要自己处理
InputStream
。让JavaFX处理并传递URL；如果
InputStream
可用，那么URL也可用：
new Image（getClass（）.getResource（“/assets/baseline\u close\u black\u 18dp.png”）。toExternalForm（））
，谢谢