JavaFX绑定失败，“无法绑定到无类型对象”。 [英] JavaFX Binding Fails with "Cannot bind to untyped object."

问题描述

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：

I have an FXML file defining a JavaFX user interface. Within the FXML file, I have the following:

...
<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，我获取 javafx.fxml.LoadException 并显示消息

When I try to load my FXML file with the following code, I get a javafx.fxml.LoadException with the message

无法绑定到无类型对象。

Cannot bind to untyped object.

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
}

有谁知道如何修改FXML以禁用选中复选框时我的微调器？我知道如何在代码中解决这个问题，但想要了解有关FXML语法的更多信息。我还要补充一点，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。

Does anyone know how to modify the FXML to disable my spinner when the checkbox is checked? I know how to go about this in code, but want to learn more about the FXML syntax. I should also add that when I remove the attempted property binding from the FXML, everything loads as expected. Thanks.

编辑

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

Due to the comment from @Groostav saying that it must be something in the ... portion of the code, I came up with a minimal, reproducible example. In my example, there are two files, which I will copy in their entirety here.

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：

When I run the main method, I get the following output:

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

如果我从FXML文件中删除 disable =$ {myCheckbox.selected}，则所有内容都按预期加载。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？我在Windows 7 Enterprise SP1 x64上运行，使用Java SE JDK 8u92 x64。

If I remove the disable="${myCheckbox.selected}" from the FXML file, everything loads as expected. In addition, I am able to bind the properties in code. Why isn't this working, and how can I modify the FXML to support this? I am running on Windows 7 Enterprise SP1 x64, using Java SE JDK 8u92 x64.

推荐答案

看来你无法设置Spinner上的禁用属性使用FXML这种方式。它在TextFields上工作正常。它可能是一个错误，我想这与加载器有关，期望定义ValueFactory的Spinner标签的主体，因此当执行将CheckBox状态链接到disable属性的尝试时，Spinner没有正确定义。

It seems that you can't set the disabled property on the Spinner using FXML this way. It works fine on TextFields. It might be a bug, I guess it's something to do with the loader expecting a body for the Spinner tag defining the ValueFactory, so the Spinner isn't defined properly when the attempt to link the CheckBox state to the disable property is carried out.

以下解决方法可能会有所帮助：

The following workaround might help:

<?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>

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