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我不能在没有得到空指针异常的情况下将JavaFX对象添加到第二个场景

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对于Javafx来说我还比较陌生，所以如果这个问题很琐碎，我感到抱歉。我目前正在使用IntelliJ与javafx一起使用，因此我正在使用场景构建器和控制器类来控制场景。我目前有2个.fxml文件，可以通过每个场景上的按钮在它们之间进行切换。这可以正常工作。现在，我试图在用户切换到第二个场景后将其添加到第二个场景。

我尝试过：

Scene Switching function in controller class

但是它给了我一个空指针异常。我认为这与图片无法正确加载有关，因此我尝试仅添加一个按钮并遇到相同的错误。我意识到这与向新场景添加任何对象有关。有没有理由我不能添加任何新元素？我相信“空”对象是我要向其中添加新元素的窗格，但它不应为空，因为我已经对其进行了初始化，并且它具有与.fxml文件中相同的fx：id。

这是我的整个控制器课：


import javafx.event.actionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.AnchorPane;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;

import java.io.IOException;
import java.util.ArrayList;

public class Controller {
    public GridPane panes1;
    public AnchorPane panes2;
    public Button switcher1;
    public Button switcher2;

    private int numplayers;

    ArrayList<Card> player1 = new ArrayList();
    ArrayList<Card> player2 = new ArrayList();
    ArrayList<Card> player3 = new ArrayList();
    ArrayList<Card> player4 = new ArrayList();

    @FXML
    public void toScene2(actionEvent event) throws IOException {
        Stage s = (Stage) ((Node)event.getsource()).getScene().getWindow();
        Parent gameroot = FXMLLoader.load(getclass().getResource("game.fxml"));
        Scene game = new Scene(gameroot,900,825);
        s.setScene(game);

        Image c = new Image("/PNG/1C.png");
        ImageView b = new ImageView();
        b.setImage(c);
        panes2.getchildren().add(b);

        //Deck deck = new Deck();
        //deck.initialize();
        //deck.shuffle();

        //for(Card a: deck.cards){
            //panes2.getchildren().add(a.show);
        //}


    }

    @FXML
    public void toScene1(actionEvent event) throws IOException {
        Stage s = (Stage) ((Node)event.getsource()).getScene().getWindow();
        Parent gameroot = FXMLLoader.load(getclass().getResource("ercmenu.fxml"));
        Scene game = new Scene(gameroot,825);
        s.setScene(game);

    }
}

这是我的主班：

import javafx.application.Application;
import javafx.event.EventType;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class Main extends Application {


    @Override
    public void start(Stage primaryStage) throws Exception{
        Parent root = FXMLLoader.load(getclass().getResource("ercmenu.fxml"));
        primaryStage.setTitle("Hello World");
        Scene menu = new Scene(root,825);
        primaryStage.setScene(menu);
        primaryStage.show();
    }


    public static void main(String[] args) {
        launch(args);
    }
}

这是第一个场景的.fxml：

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.*?>
<?import javafx.scene.text.*?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>

<?import sample.Card?>
<GridPane fx:id="panes1" alignment="CENTER" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="527.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.Controller">
  <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 minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
  </rowConstraints>
   <children>
      <Button fx:id="switcher1" alignment="CENTER" contentDisplay="CENTER" mnemonicParsing="false" onaction="#toScene2" prefHeight="52.0" prefWidth="267.0" text="Switch to 2" GridPane.rowIndex="2">
         <font>
            <Font name="System Bold" size="39.0" />
         </font>
         <cursor>
            <Cursor fx:constant="OPEN_HAND" />
         </cursor>
      </Button>
      <Button mnemonicParsing="false" prefHeight="37.0" prefWidth="264.0" text="Button" GridPane.rowIndex="1" />
      <Button mnemonicParsing="false" prefHeight="38.0" prefWidth="264.0" text="Play" />
      <Button mnemonicParsing="false" text="Button" GridPane.rowIndex="3" />
   </children>
</GridPane>

这是第二个场景的.fxml：

<?xml version="1.0" encoding="UTF-8"?>

<?import java.lang.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.image.*?>
<?import javafx.scene.layout.*?>

<AnchorPane fx:id="panes2" 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="sample.Controller">
   <children>
      <Button fx:id="switcher2" layoutX="12.0" layoutY="13.0" mnemonicParsing="false" onaction="#toScene1" prefHeight="4.0" prefWidth="60.0" text="Back" />
      <ImageView fitHeight="105.0" fitWidth="239.0" layoutX="403.0" layoutY="47.0" pickOnBounds="true" preserveRatio="true" rotate="45.0" AnchorPane.rightAnchor="-20.192703247070312" AnchorPane.topAnchor="47.0">
         <image>
            <Image url="@../PNG/back_cards-07.png" />
         </image>
      </ImageView>
   </children>
</AnchorPane>

错误消息：

/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/bin/java "-javaagent:/Users/nicholaskoran/library/Application Support/JetBrains/Toolbox/apps/IDEA-U/ch-0/193.6015.11/IntelliJ IDEA.app/Contents/lib/idea_rt.jar=50423:/Users/nicholaskoran/library/Application Support/JetBrains/Toolbox/apps/IDEA-U/ch-0/193.6015.11/IntelliJ IDEA.app/Contents/bin" -Dfile.encoding=UTF-8 -classpath /library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/charsets.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/deploy.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/ext/localedata.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/ext/sunec.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/javaws.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/jce.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/jfr.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/jfxswt.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/jsse.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/management-agent.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/plugin.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/resources.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/rt.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/lib/ant-javafx.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/lib/dt.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/lib/javafx-mx.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/lib/jconsole.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/lib/packager.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/lib/sa-jdi.jar:/library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/lib/tools.jar:/Users/nicholaskoran/IdeaProjects/Q2ERC/out/production/Q2ERC sample.Main
objc[13364]: Class JavaLaunchHelper is implemented in both /library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/bin/java (0x10c3f64c0) and /library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home/jre/lib/libinstrument.dylib (0x10c4704e0). One of the two will be used. Which one is undefined.
Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.invocationTargetException
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1774)
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657)
    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:8413)
    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:96)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
    at com.sun.javafx.event.CompositeEventHandler$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$MouseHandler.process(Scene.java:3757)
    at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:380)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:294)
    at java.security.accessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:416)
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:415)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
    at com.sun.glass.ui.View.notifyMouse(View.java:937)
Caused by: java.lang.reflect.invocationTargetException
    at sun.reflect.NativeMethodaccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodaccessorImpl.invoke(NativeMethodaccessorImpl.java:62)
    at sun.reflect.DelegatingMethodaccessorImpl.invoke(DelegatingMethodaccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
    at sun.reflect.GeneratedMethodaccessor1.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodaccessorImpl.invoke(DelegatingMethodaccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769)
    ... 45 more
Caused by: java.lang.NullPointerException
    at sample.Controller.toScene2(Controller.java:39)
    ... 55 more

谢谢！

q5070212 回答：我不能在没有得到空指针异常的情况下将JavaFX对象添加到第二个场景
暂时没有好的解决方案，如果你有好的解决方案，请发邮件至：iooj@foxmail.com
fxmlintellij-ideajavajavafxscenebuilder
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