问

无法从JavaFX中的MenuItem获取场景

mobiledu2502926601 发布于 2023-02-10 12:54

java

我试图基于menuItem单击更改javafx阶段中的场景.这是我的sample.fxml:

这是我的Controller.java:

package sample;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.MenuItem;
import javafx.stage.Stage;

import java.net.URL;
import java.util.ResourceBundle;

public class Controller implements Initializable {
    @FXML
    protected void onManageAccountsMenuActionPerformed(ActionEvent event) {
        System.out.println("Manage Accbtnclick");
//        Node node=(Node) event.getSource();
//        Stage stage=(Stage) node.getScene().getWindow();
//
//        Scene scene = new Scene(root);
//        stage.setScene(scene);
//        stage.show();
    }
    @FXML
    protected void onTweetsMenuActionPerformed(ActionEvent event) {
        System.out.println("Manage Accbtnclick");
    Node node= (Node)event.getSource();
    Stage stage=(Stage) node.getScene().getWindow();
    Scene scene = Main.screens.get("tweet");
    stage.setScene(scene);
    stage.show();
    }

    @Override
    public void initialize(URL url, ResourceBundle resourceBundle) {
        //To change body of implemented methods use File | Settings | File Templates.
    }
}

这是我的Main.java:

package sample;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.geometry.Pos;
import javafx.scene.Group;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.ProgressBar;
import javafx.scene.control.ProgressIndicator;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

import java.io.IOException;
import java.util.HashMap;

public class Main extends Application {

    public static HashMap screens=new HashMap();

    @Override
    public void start(Stage stage) {
        try {
            Parent accountScreen= FXMLLoader.load(getClass().getResource("sample.fxml"));
            Parent tweetScreen=FXMLLoader.load(getClass().getResource("tweetform.fxml"));
            //Parent retweetScreen=FXMLLoader.load(getClass().getResource("retweetform.fxml"));
            screens.put("account",new Scene(accountScreen));
            screens.put("tweet",new Scene(tweetScreen));
            //screens.put("retweet",new Scene(retweetScreen));
            stage.setTitle("Manage Accounts");
            stage.setScene(screens.get("account"));
            stage.show();
        } catch (IOException e) {
            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        }

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

当我点击Accounts Menu下的menuItem Manage时,我得到以下异常:

    "C:\Program Files\Java\jdk1.7.0_17\bin\java" -Didea.launcher.port=7541 "-Didea.launcher.bin.path=C:\Program Files (x86)\JetBrains\IntelliJ IDEA 12.1.4\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.7.0_17\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\jce.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\jfxrt.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\resources.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\rt.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.7.0_17\jre\lib\ext\zipfs.jar;C:\Users\rahulserver\IdeaProjects\DrawingText\out\production\DrawingText;C:\Program Files (x86)\JetBrains\IntelliJ IDEA 12.1.4\lib\idea_rt.jar" com.intellij.rt.execution.application.AppMain sample.Main
Manage Accbtnclick
Manage Accbtnclick
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1440)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:28)
    at javafx.event.Event.fireEvent(Event.java:171)
    at javafx.scene.control.MenuItem.fire(MenuItem.java:456)
    at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.doSelect(ContextMenuContent.java:1188)
    at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer$6.handle(ContextMenuContent.java:1139)
    at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer$6.handle(ContextMenuContent.java:1137)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
    at javafx.event.Event.fireEvent(Event.java:171)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3328)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3168)
    at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3123)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1563)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2265)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:250)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:173)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:292)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:528)
    at com.sun.glass.ui.View.notifyMouse(View.java:922)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29)
    at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:73)
    at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:55)
    at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:269)
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1435)
    ... 40 more
Caused by: java.lang.ClassCastException: javafx.scene.control.MenuItem cannot be cast to javafx.scene.Node
    at sample.Controller.onTweetsMenuActionPerformed(Controller.java:29)
    ... 50 more

那么如何从菜单项单击事件处理程序中获取包含的舞台/场景？

编辑该行

Node node= (Node)event.getSource();

在controller.java中是第29行,它给出了问题.

1 个回答

您的实际错误显示在堆栈跟踪的倒数第二行:
```
Caused by: java.lang.ClassCastException: javafx.scene.control.MenuItem cannot be cast to javafx.scene.Node
    at sample.Controller.onTweetsMenuActionPerformed(Controller.java:29)
```
此错误指的是您的控制器中的以下行:
```
Node node= (Node)event.getSource();
```
查看JavaFX API Docs,MenuItem和Menu都不是Node的子类. http://docs.oracle.com/javafx/2/api/javafx/scene/control/MenuItem.html http://docs.oracle.com/javafx/2/api/javafx/scene/control/Menu.html

我建议将源作为Object抓取,然后在继续之前检查其类型.另外,我遇到了使用getSource()方法的问题; getTarget()方法对我来说效果更好.无论哪种方式,你仍然需要一种方法来进入舞台.

为此,您可能希望fx:id在FXML中使用标记而不是id标记.这将允许您将FXML元素直接注入控制器.例如,您可以通过将MenuBar元素注入控制器,从MenuBar(它是Node的子类)中获取Stage.

在FXML中:
```
<MenuBar fx:id="myMenuBar" layoutY="0.0" max pref useSystemMenuBar="false" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="2.0">
```
在控制器中:
```
public class Controller implements Initializable {
    @FXML MenuBar myMenuBar;
    ...
    @FXML
    protected void onTweetsMenuActionPerformed(ActionEvent event) {
        System.out.println("Manage Accbtnclick");
        Stage stage = (Stage) myMenuBar.getScene().getWindow();
        Scene scene = Main.screens.get("tweet");
        stage.setScene(scene);
        stage.show();
    }
    ...
}
```
你可能需要在这里做一些调整,但希望它有所帮助.
2023-02-10 12:57 回答

mobiledu2502926247

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