JavaFX FileChooser引发错误（可能很容易修复，但仍然困惑）
我正在尝试使用以下代码打开FileChooser：
package back_end.controllers; import javafx.fxml.FXML; import javafx.fxml.Initializable; import javafx.scene.control.Button; import javafx.scene.control.ListView; import javafx.scene.layout.BorderPane; import javafx.stage.FileChooser; import java.io.File; import java.net.URL; import java.util.ResourceBundle; /** * Created by Quinn McHugh on 4/15/2014. */ public class StartScreen_Controller implements Initializable { @FXML private ListView lstRecents; @FXML private Button btnBrowse; @FXML private BorderPane borderPane; @Override public void initialize(URL fxmlFileLocation, ResourceBundle resources){ lstRecents = new ListView(); btnBrowse = new Button(); borderPane = new BorderPane(); } public void openFile(){ /* Presents a file chooser but does nothing functionally. */ FileChooser fc = new FileChooser(); File f = fc.showOpenDialog(btnBrowse.getScene().getWindow()); } } 但它在openFile（）方法中搞砸了。 编译器抛出NullPointerException并显示以下错误消息：
Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1760) at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1643) at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86) at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238) at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191) at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49) at javafx.event.Event.fireEvent(Event.java:198) at javafx.scene.Node.fireEvent(Node.java:8196) at javafx.scene.control.Button.fire(Button.java:185) at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182) at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:97) at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:90) at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218) at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80) at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238) at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191) at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54) at javafx.event.Event.fireEvent(Event.java:198) at javafx.scene.Scene$MouseHandler.process(Scene.java:3712) at javafx.scene.Scene$MouseHandler.access$1800(Scene.java:3440) at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1663) at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2455) at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:326) at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:251) at java.security.AccessController.doPrivileged(Native Method) at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:360) at com.sun.glass.ui.View.handleMouseEvent(View.java:526) at com.sun.glass.ui.View.notifyMouse(View.java:898) at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) at com.sun.glass.ui.win.WinApplication.access$300(WinApplication.java:39) at com.sun.glass.ui.win.WinApplication$4$1.run(WinApplication.java:112) at java.lang.Thread.run(Thread.java:744) Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:483) at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71) at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:483) at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275) at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1757) ... 47 more Caused by: java.lang.NullPointerException at back_end.controllers.StartScreen_Controller.openFile(StartScreen_Controller.java:38) ... 57 more
任何帮助将不胜感激，因为我是JavaFX的新手和使用Scene Builder。
这是我在两天内看到的第三个问题，这个问题是由人们重新初始化由FXMLLoader字段引起的。
@FXML是告诉FXMLLoader使用通过解析FXML文件创建的对象初始化该字段。 然后你执行
btnBrowse = new Button();
在您的initialize()方法中，您创建一个新按钮，并且不再引用在解析FXML时为您创建的按钮。
所以，现在很明显btnBrowse.getScene()将返回null （因为按钮从未添加到场景中）和btnBrowse.getScene().getWindow()将生成NullPointerException 。
只需从initialize()方法中取出这三行。
我可以问你在哪里重新初始化那些字段吗？ 如果有一些流行的资源正在传播错误的代码，则需要将其删除。