JavaFX绑定失败,"无法绑定到无类型对象".

Question

我有一个定义JavaFX用户界面的FXML文件.在FXML文件中,我有以下内容:

...
<Checkbox fx:id="myCheckbox" ... />
<Spinner disable="${myCheckbox.selected}" ... />
...

当我尝试使用以下代码加载我的FXML文件时,我得到了一条javafx.fxml.LoadException消息

无法绑定到无类型对象.

final Class<?> controllerClass = ...;
final FXMLLoader fxmlLoader = new FXMLLoader();
final String fxmlPath = controllerClass.getSimpleName() + ".fxml";
try (final InputStream fxmlStream = controllerClass.getResourceAsStream(fxmlPath)) {
    fxmlLoader.load(fxmlStream);
    final Object controller = fxmlLoader.<Object>getController();
    return controller
}

当选中复选框时,有没有人知道如何修改FXML以禁用我的微调器？我知道如何在代码中进行此操作,但想要了解有关FXML语法的更多信息.我还应该补充一点,当我从FXML中删除尝试的属性绑定时,所有内容都按预期加载.谢谢.

编辑

由于@Groostav的评论说它必须是...代码部分的内容,我想出了一个最小的,可重现的例子.在我的示例中,有两个文件,我将在此处完整复制.

Main.java:

package test;

import java.io.InputStream;

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

public class Main extends Application {
    public static void main(final String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage window) throws Exception {
        final FXMLLoader fxmlLoader = new FXMLLoader();
        final String fxmlPath = "Example.fxml";
        final Parent root;
        try (final InputStream fxmlStream = getClass().getResourceAsStream(fxmlPath)) {
            root = (Parent)fxmlLoader.load(fxmlStream);
        }
        final Scene scene = new Scene(root);
        window.setScene(scene);
        window.show();
    }
}

Example.fxml:

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

<?import javafx.scene.control.CheckBox?>
<?import javafx.scene.control.Spinner?>
<?import javafx.scene.layout.HBox?>

<HBox xmlns="http://javafx.com/javafx/8.0.65" xmlns:fx="http://javafx.com/fxml/1"
      alignment="BASELINE_LEFT" spacing="15">
  <children>
    <CheckBox fx:id="myCheckbox" text="Disable?" mnemonicParsing="false" />
    <Spinner disable="${myCheckbox.selected}" />
  </children>
</HBox>

当我运行main方法时,我得到以下输出:

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:498)
    at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
    at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
    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.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$155(LauncherImpl.java:182)
    at java.lang.Thread.run(Thread.java:745)
Caused by: javafx.fxml.LoadException: Cannot bind to untyped object.
unknown path:12

    at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2597)
    at javafx.fxml.FXMLLoader.access$100(FXMLLoader.java:103)
    at javafx.fxml.FXMLLoader$Element.processPropertyAttribute(FXMLLoader.java:299)
    at javafx.fxml.FXMLLoader$Element.processInstancePropertyAttributes(FXMLLoader.java:235)
    at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:749)
    at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2707)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2425)
    at test.Main.start(Main.java:22)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
    ... 1 more
Exception running application test.Main

如果我disable="${myCheckbox.selected}"从FXML文件中删除,一切都按预期加载.另外,我能够在代码中绑定属性.为什么这不起作用,如何修改FXML以支持这一点？我使用Java SE JDK 8u92 x64在Windows 7 Enterprise SP1 x64上运行.

Answer 1

看来您无法通过这种方式使用 FXML 在 Spinner 上设置禁用属性。它在文本字段上运行良好。这可能是一个错误，我猜想这与加载程序期望定义 ValueFactory 的 Spinner 标签的主体有关，因此当尝试将 CheckBox 状态链接到禁用属性时，Spinner 没有正确定义。

以下解决方法可能会有所帮助：

<?xml version="1.0" encoding="UTF-8"?>
<?language javascript?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.util.* ?>
<?import javafx.scene.*?>
<?import javafx.scene.control.* ?>
<?import javafx.scene.layout.* ?>
<?import javafx.scene.control.SpinnerValueFactory.IntegerSpinnerValueFactory?>

<HBox xmlns="http://javafx.com/javafx/8.0.65" xmlns:fx="http://javafx.com/fxml/1"
      alignment="BASELINE_LEFT" spacing="15">
    <fx:script>
    function handleCheckBoxAction(event) {
       mySpinner.disable = (! mySpinner.disabled);
    }
    </fx:script>
  <children>
    <CheckBox fx:id="myCheckbox" text="Disable?" mnemonicParsing="false" onAction="handleCheckBoxAction(event);" />
    <Spinner fx:id="mySpinner">
        <valueFactory>
        <SpinnerValueFactory.IntegerSpinnerValueFactory min="0" max="10"/>
      </valueFactory>
    </Spinner>
  </children>
</HBox>