JavaFX 8：javafx.fxml.LoadException-fxmlLoader.load（）不起作用，但fxmlLoader.getController（）起作用

Question

嘗試從FXML文件加載控制器時出現LoadException。 這是FXML文件：

 <?xml version="1.0" encoding="UTF-8"?> <?import javafx.scene.control.*?> <?import java.lang.*?> <?import javafx.scene.layout.*?> <VBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="Interface.ChangeProjoOrderController"> <children> <HBox prefHeight="100.0" prefWidth="200.0"> <children> <ScrollPane prefHeight="200.0" prefWidth="200.0"> <content> <AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="200.0" prefWidth="200.0"> <children> <GridPane> <columnConstraints> <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" /> <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" /> </columnConstraints> <rowConstraints> <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" /> <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" /> <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" /> </rowConstraints> </GridPane> </children> </AnchorPane> </content> </ScrollPane> <VBox prefHeight="200.0" prefWidth="100.0"> <children> <Button mnemonicParsing="false" text="Button" /> <Button mnemonicParsing="false" text="Button" /> </children> </VBox> </children> </HBox> <ToolBar prefHeight="40.0" prefWidth="200.0"> <items> <Button mnemonicParsing="false" text="Button" /> <Button mnemonicParsing="false" text="Button" /> <Button mnemonicParsing="false" text="Button" /> <Button mnemonicParsing="false" text="Button" /> </items> </ToolBar> <HBox prefHeight="100.0" prefWidth="200.0"> <children> <Button mnemonicParsing="false" text="Button" /> <Button mnemonicParsing="false" text="Button" /> </children> </HBox> </children> </VBox> 

加載FXML的窗口是：

 package Interface; import java.io.IOException; import java.util.ArrayList; import java.util.logging.Logger; import javafx.fxml.FXMLLoader; import javafx.scene.Parent; import javafx.scene.Scene; import javafx.scene.layout.VBox; import javafx.stage.Stage; import Engine.PackageLight.Projector; public class ChangeProjoOrderWindow { private MainWindowController mainController; private FXMLLoader fxmlLoader = null; private VBox root = null;//TODO uncomment me //private Parent root = null;//TODO delete me private ChangeProjoOrderController controller; private Scene scene; private Stage stage; private static final Logger logUI = Logger.getLogger("UI"); ChangeProjoOrderWindow(MainWindowController c) { mainController = c; try { fxmlLoader = new FXMLLoader(getClass().getResource("fxml/projectorOrder.fxml")); root = (VBox)fxmlLoader.load();//TODO uncomment me //root = (Parent)fxmlLoader.load();//TODO delete me //XXX DO NOT do this !! The controller will stay null (uninitialized) //root = FXMLLoader.load(getClass().getResource("fxml/orderProjo.fxml")); } catch(IOException e) { logUI.severe("Error: Cannot load the FXML file 'projectorOrder.fxml'."); e.printStackTrace(); } controller = fxmlLoader.<ChangeProjoOrderController>getController(); if(controller == null) System.err.println("controller is null"); scene = new Scene(root); System.exit(0); stage = new Stage(); stage.setOnCloseRequest(we -> { // Application termination event c.setChangeProjectorOrderDisableStatus(false); stage.close(); logUI.fine("orderProjo terminated."); }); mainController.windows.executePreChangeProjectorOrder(); stage.setTitle("Modifier l'ordre des projecteurs"); stage.setScene(scene); stage.show(); controller.setMainController(mainController); controller.setStage(stage); } protected void setProjectors(ArrayList<Projector> projectors){controller.setProjectors(projectors);} } 

這是控制器：

 package Interface; import java.net.URL; import java.util.ArrayList; import java.util.ResourceBundle; import java.util.logging.Logger; import javafx.fxml.FXML; import javafx.fxml.Initializable; import javafx.scene.control.Button; import javafx.scene.control.Label; import javafx.scene.layout.GridPane; import javafx.stage.Stage; import Engine.PackageLight.Projector; public class ChangeProjoOrderController implements Initializable { /*@FXML private Button up; @FXML private Button down; @FXML private Button newProjo; @FXML private Button remove; @FXML private Button duplicate; @FXML private Button edit; @FXML private Button ok; @FXML private Button cancel; @FXML private GridPane gridPane;*/ private MainWindowController mainController; private Stage stage; private ArrayList<Projector> projectorList = null; private static final Logger logUI = Logger.getLogger("UI"); @Override public void initialize(URL location, ResourceBundle resources) { /*cancel.setOnAction(event -> { logUI.info("cancel"); mainController.setChangeProjectorOrderDisableStatus(false); stage.close(); }); ok.setOnAction(event -> { logUI.info("ok"); mainController.setChangeProjectorOrderDisableStatus(false); stage.close(); });*/ initProjectors(); } private void initProjectors() { for(int i=0; i<projectorList.size(); i++) { Label curr = new Label(Integer.toString(i)); GridPane.setColumnIndex(curr, 0); GridPane.setRowIndex(curr, i); } } protected void setMainController(MainWindowController c){mainController = c;} protected void setStage(Stage s){stage = s;} protected void setProjectors(ArrayList<Projector> projectors){projectorList = projectors;} } 

最后，堆棧跟蹤：

 INFO [UI] Interface.Windows - changeProjoOrder Changing the order of the projectors... ?[0m?[31m?[1mSEVERE [UI] Interface.ChangeProjoOrderWindow - <init> Error: Cannot load the FXML file 'projectorOrder.fxml'. ?[0mjavafx.fxml.LoadException: /home/filou/workspace/java/syncart/bin/Interface/fxml/projectorOrder.fxml at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2605) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2583) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2445) at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2413) at Interface.ChangeProjoOrderWindow.<init>(ChangeProjoOrderWindow.java:35) at Interface.Windows.changeProjoOrder(Windows.java:151) at Interface.MainWindowController.changeProjoOrder(MainWindowController.java:308) 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:497) 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:497) at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275) at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1767) at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1653) 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.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) 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.control.MenuItem.fire(MenuItem.java:462) at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.doSelect(ContextMenuContent.java:1405) at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.lambda$createChildren$341(ContextMenuContent.java:1358) at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer$$Lambda$398/1949840625.handle(Unknown Source) 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.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:3758) at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3486) at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762) at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2495) at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:350) at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:275) at java.security.AccessController.doPrivileged(Native Method) at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$350(GlassViewEventHandler.java:385) at com.sun.javafx.tk.quantum.GlassViewEventHandler$$Lambda$357/365619965.get(Unknown Source) at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:404) at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:384) at com.sun.glass.ui.View.handleMouseEvent(View.java:555) at com.sun.glass.ui.View.notifyMouse(View.java:927) at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method) at com.sun.glass.ui.gtk.GtkApplication.lambda$null$48(GtkApplication.java:139) at com.sun.glass.ui.gtk.GtkApplication$$Lambda$42/1327763628.run(Unknown Source) at java.lang.Thread.run(Thread.java:745) Caused by: java.lang.NullPointerException at Interface.ChangeProjoOrderController.initProjectors(ChangeProjoOrderController.java:58) at Interface.ChangeProjoOrderController.initialize(ChangeProjoOrderController.java:53) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2552) ... 61 more Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1770) at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1653) at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86) at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238) at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49) at javafx.event.Event.fireEvent(Event.java:198) at javafx.scene.control.MenuItem.fire(MenuItem.java:462) at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.doSelect(ContextMenuContent.java:1405) at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.lambda$createChildren$341(ContextMenuContent.java:1358) at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer$$Lambda$398/1949840625.handle(Unknown Source) at com.sun.javafx.event.CompositeEventHandler$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.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$MouseHandler.process(Scene.java:3758) at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3486) at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762) at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2495) at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:350) at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:275) at java.security.AccessController.doPrivileged(Native Method) at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$350(GlassViewEventHandler.java:385) at com.sun.javafx.tk.quantum.GlassViewEventHandler$$Lambda$357/365619965.get(Unknown Source) at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:404) at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:384) at com.sun.glass.ui.View.handleMouseEvent(View.java:555) at com.sun.glass.ui.View.notifyMouse(View.java:927) at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method) at com.sun.glass.ui.gtk.GtkApplication.lambda$null$48(GtkApplication.java:139) at com.sun.glass.ui.gtk.GtkApplication$$Lambda$42/1327763628.run(Unknown Source) at java.lang.Thread.run(Thread.java:745) Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71) at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275) at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1767) ... 46 more Caused by: java.lang.NullPointerException: Root cannot be null at javafx.scene.Scene.<init>(Scene.java:336) at javafx.scene.Scene.<init>(Scene.java:194) at Interface.ChangeProjoOrderWindow.<init>(ChangeProjoOrderWindow.java:50) at Interface.Windows.changeProjoOrder(Windows.java:151) at Interface.MainWindowController.changeProjoOrder(MainWindowController.java:308) ... 56 more 

好。 現在問題似乎出在線路上

 root = (VBox)fxmlLoader.load();//TODO uncomment me 

這會導致IOException。 但是之后

 controller = fxmlLoader.<ChangeProjoOrderController>getController(); if(controller == null) System.err.println("controller is null"); 

不要打印“控制器為空”。 因此，控制器已正確加載，但“ root”不是。 我檢查了“ @FXML”標簽（最后我注釋掉了……無濟於事），即FXML文件中的“ fx：controller”（它與另一個起作用的文件相同，即Interface.xxx ），我從頭開始使用SceneBuilder 2.0重新創建了窗口，以確保FXML生成正確，我嘗試將“ root”設置為“ Parent”或“ VBox”，並將我的文件與其他可以正常工作的文件進行了比較。

內置的窗口不會出現。

我正在使用：LUbuntu 3.13.0-46-generic，JavaFX 8 u40，Eclipse Mars Milestone 3（4.5.0M3）內部版本號20141113-0320，JavaFx SceneBuilder 2.0-b20

那么，為什么會有這個例外？ 它從何而來 ？

我不確定是否很清楚，我已經在這段代碼中使用了很長時間了：P如果需要更多信息，請告訴我； 我會提供。

謝謝

Answer 1

堆棧跟蹤顯示異常來自ChangeProjoOrderController第58行。

我猜這是

for(int i=0; i<projectorList.size(); i++)

這很有意義，因為您進行了初始化

private ArrayList<Projector> projectorList = null;

並且至少在加載FXML之后（並調用initalize()方法），才更改其值。