java - FXML 加载的 javafx main 方法中的错误未得到纠正

Question

我有一个用 javafx 创建的可用计算器程序。然而，为了改进我的程序，我决定将按键事件也包含在输入数字中。为此，我必须调用 Controller 类的实例来将参数从主类传递给我的 FXMLController，在主类中我将 keyevent 记录到了其中。但是，在我修改代码后，它没有编译，在我的主类中显示异常。 它给出 AnchorPane 无法转换为 javafx.fxml.FXMLLoader

这是之前的工作代码:

public class Mycalc extends Application {

@Override
public void start(Stage stage) throws Exception {

        stage.initStyle(StageStyle.TRANSPARENT);
        Parent root =FXMLLoader.load(getClass().getResource("calc1.fxml"));
        Scene scene = new Scene(root,Color.TRANSPARENT);
        stage.setScene(scene);
        stage.show();
    }

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

}

这是当前代码(有错误):

public class Mycalc extends Application {

@Override
public void start(Stage stage) throws Exception {
    stage.initStyle(StageStyle.TRANSPARENT);

    FXMLLoader loader= FXMLLoader.load(getClass().getResource("calc1.fxml"));
    Parent root = loader.load();


    Scene scene = new Scene(root,Color.TRANSPARENT);

    stage.setScene(scene);
    stage.show();
    calc1Controller controller= loader.getController();
    scene.setOnKeyPressed(new EventHandler<KeyEvent>() 
    {
        @Override
        public void handle(KeyEvent keyEvent) 
        {

            switch (keyEvent.getCode()) 
            {
                case DIGIT1:
                    controller.handleDigit("1");
                    break ;
                case DIGIT2:
                    controller.handleDigit("2");
                    break ;
                case DIGIT3:
                    controller.handleDigit("3");
                    break ;
                case DIGIT4:
                    controller.handleDigit("4");
                    break ;
                case DIGIT5:
                    controller.handleDigit("5");
                    break ;
                case DIGIT6:
                    controller.handleDigit("6");
                    break ;
                case DIGIT7:
                    controller.handleDigit("7");
                    break ;
                case DIGIT8:
                    controller.handleDigit("8");
                    break ;
                case DIGIT9:
                    controller.handleDigit("9");
                    break ;
                case ADD:
                    controller.handleOperatorkey("+");
                    break ;
                case SUBTRACT:
                    controller.handleOperatorkey("-");
                    break ;
                case MULTIPLY:
                    controller.handleOperatorkey("*");
                    break ;
                case DIVIDE:
                    controller.handleOperatorkey("/");
                    break ;
                case EQUALS:
                    controller.handleEqualKey();
                    break ;
            }
        }   
    });
}

但是我在运行时收到以下消息:

   Exception in Application start method
   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 com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:367)
at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:305)
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.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
    Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:894)
at com.sun.javafx.application.LauncherImpl.access$000(LauncherImpl.java:56)
at com.sun.javafx.application.LauncherImpl$1.run(LauncherImpl.java:158)
at java.lang.Thread.run(Thread.java:745)
    Caused by: java.lang.ClassCastException: javafx.scene.layout.AnchorPane cannot be cast to javafx.fxml.FXMLLoader
at mycalc.Mycalc.start(Mycalc.java:32)
at com.sun.javafx.application.LauncherImpl$8.run(LauncherImpl.java:837)
at com.sun.javafx.application.PlatformImpl$7.run(PlatformImpl.java:335)
at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:301)
at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:298)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl$6.run(PlatformImpl.java:298)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
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)
... 1 more
    Exception running application mycalc.Mycalc

我也用 AnchorPane root 替换了 Parent root，但我仍然遇到相同的错误。请帮忙。

Answer 1

Caused by: java.lang.ClassCastException: javafx.scene.layout.AnchorPane cannot be cast to javafx.fxml.FXMLLoader

而不是:

FXMLLoader loader= FXMLLoader.load(getClass().getResource("calc1.fxml"));
Parent root = loader.load();

尝试(未经测试)

FXMLLoader loader= new FXMLLoader(getClass().getResource("calc1.fxml"));
Parent root = loader.load();

或者(如果您的 FXML 根元素是 AnchorPane):

FXMLLoader loader= new FXMLLoader(getClass().getResource("calc1.fxml"));
AnchorPane root = loader.load();

FXMLLoader.load 加载 FXML 文件。它不返回 FXMLLoader。