链接 JavaFX 文件 - FXMLController 文件、FXML 文件、Java 代码

Question

我是 JavaFX 的新手，我正在构建一个 GUI 游戏。我之前用Java编写了游戏的逻辑，现在我正在尝试将它与SceneBuilder集成。这种怀疑可能非常基本和明显，但我似乎无法理解我哪里出错了。

我必须在我的 SceneBuilder 画布上创建一个计时器标签，它从 java 代码中提取时间并在 GUI 上更新它。这个计时器不是常规计时器，这就是为什么我不能只在控制器中使用时钟的原因。我有可以使用从 Java 代码中获得的值。 这里是：

FXML 控制器文件：

public class SampleController implements Initializable {

    public SampleController getSampleController(){
        return this;
    }

@FXML private Label displayTime;

@FXML
public void updatePage(String data){
    displayTime.setText(data);
}

@FXML
private void handleStartGameA1(ActionEvent event) throws InterruptedException{
System.out.println("Game has been started!");
World w = new World();
w.runGame();
}

FXML 文件：

  <Label id="displayTime" fx:id="displayTime" layoutX="381.0" layoutY="125.0" prefHeight="23.0" prefWidth="301.0">
     <font>
         <Font size="18.0" />
     </font>
  </Label>

Java 文件：

public class World {
    public static Clock WorldClock; // Clock class only to get the custom time

    public World(){
        WorldClock = new Clock();
        public void runGame() throws InterruptedException{
        for (int minute=0; minute<=WorldProperty.MaxMinutes/10; minute++){

        // irrelevant code

        FXMLLoader fxmlLoader = new FXMLLoader();
        SampleController sc = new SampleController();
        sc.getSampleController();
        sc.updatePage(WorldClock.getTime());
        }
    }
}

运行时错误：

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$MouseEventNotification.run(GlassViewEventHandler.java:381)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:417)
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:416)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
    at com.sun.glass.ui.View.notifyMouse(View.java:937)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
    at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769)
    ... 45 more
Caused by: java.lang.NullPointerException
    at javafxapplication1.SampleController.updatePage(SampleController.java:41)
    at World.World.runGame(World.java:102)
    at javafxapplication1.SampleController.handleStartGameA1(SampleController.java:52)
    ... 55 more

可能出了什么问题？我觉得我通过创建一个 SampleController 构造函数是非常规的，但我已经收集到它可以从在线资源中工作。另外，在updatePage(String data) 函数中，如果我不更新标签并简单地打印一条语句System.out.println("The time is: " + data);，它就可以很好地工作。 这让我相信由于某种原因标签没有正确更新。我该怎么做才能解决这个问题？

Answer 1

您不加载 FXML，因此不会创建 UI 组件，包括标签，并且您不将控制器连接到 FXML 加载器。

你需要类似的东西

FXMLLoader fxmlLoader = new FXMLLoader();
SampleController sc = new SampleController();
fxmlLoader.setController(sc);
fxmlLoader.setLocation(getClass().getResource("path/to/file.fxml"));
Parent root = fxmlLoader.load();
// display root somewhere...