java - 无法在 javafx 中设置静态 TextField 的值

Question

这个问题已经有答案了:

javafx 8 compatibility issues - FXML static fields or methods (1 个回答)

已关闭 5 年前。

我正在开发一个用于保险目的的程序，其中有一个名为引用 key 的文本字段，该引用 key 是在我每次查看面板时随机生成的其他场景和类需要这个 Reference Key ，所以我将其设为静态，以便所有类都可以直接访问此实例!

我的问题是，当我为 textfield 设置文本时，即使来自包含 textfield 实例的同一个类，我也会收到异常，但令人震惊的是当我删除 TextField 实例的静态关键字时，它完美地工作并且它的文本发生了变化!!

我的代码如下

@FXML
public static TextField ReferenceKey;
.
.
.
@Override
    public void initialize(URL url, ResourceBundle rb) {
ReferenceKey.setText("ABCD");
}

我遇到的异常

at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2579)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
    at database.project.SceneManager.LoadPanel(SceneManager.java:55)
    at database.project.HomePageController.lambda$initialize$2(HomePageController.java:83)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.event.Event.fireEvent(Event.java:198)
    at javafx.scene.Scene$ClickGenerator.postProcess(Scene.java:3470)
    at javafx.scene.Scene$ClickGenerator.access$8100(Scene.java:3398)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3766)
    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$354(GlassViewEventHandler.java:417)
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:416)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
    at com.sun.glass.ui.View.notifyMouse(View.java:937)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
    at database.project.CustmorInfoController.initialize(CustmorInfoController.java:100)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
    ... 37 more

我不知道为什么在倒数第四行显示

Caused by: java.lang.NullPointerException

我确信我只导入了 javafx 的文本字段

有人可以帮我吗提前致谢。

Answer 1

JavaFX 不会将组件注入(inject)静态字段。如果可能，您应该传递此类的实例，而不是使用静态字段。这可以通过允许使用此类的方法和类将此类作为参数来完成。您还可以使用 FXMLLoader#getController 获取 Controller .

但是，如果需要，您可以拥有非静态字段并在initialize 上设置静态字段:

@FXML
private TextField ReferenceKey;

public static TextField referenceKeyPublic;

...

@Override
public void initialize(URL url, ResourceBundle rb) {
    ClassName.referenceKeyPublic = ReferenceKey;
}