Fxml没有看到onAction

我在JavaFX上遇到了一些问题 . 它不起作用 . 我有这样的错误 .

"C:\Program Files\Java\jdk1.8.0_161\bin\java" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2017.3.4\lib\idea_rt.jar=51165:C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2017.3.4\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_161\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\rt.jar;C:\Users\kubci\IdeaProjects\FinallyProject\out\production\FinallyProject;C:\Users\kubci\IdeaProjects\FinallyProject\mysql-connector-java-5.1.6.jar" LoginPanel
    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$154(LauncherImpl.java:182)
        at java.lang.Thread.run(Thread.java:748)
    Caused by: javafx.fxml.LoadException: fx:controller can only be applied to root element.
    /C:/Users/kubci/IdeaProjects/FinallyProject/out/production/FinallyProject/stackPanel.fxml:24

        at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2597)
        at javafx.fxml.FXMLLoader.access$100(FXMLLoader.java:103)
        at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:909)
        at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:971)
        at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:220)
        at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:744)
        at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2707)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
        at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2409)
        at LoginPanel.start(LoginPanel.java:28)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$161(LauncherImpl.java:863)
        at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$174(PlatformImpl.java:326)
        at com.sun.javafx.application.PlatformImpl.lambda$null$172(PlatformImpl.java:295)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.sun.javafx.application.PlatformImpl.lambda$runLater$173(PlatformImpl.java:294)
        at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
        at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
        at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
        ... 1 more
    Exception running application LoginPanel

我给你我的Java和Fxml代码 . 我需要帮助 . 我只是研究Javafx，我不知道该怎么做 .

Java的

import javafx.application.Application;
import javafx.event.Event;
import javafx.event.EventHandler;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.FlowPane;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import javafx.stage.StageStyle;

import java.io.IOException;

public class LoginPanel extends Application {

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

    @Override
    public void start(Stage primaryStage) throws IOException {
        FXMLLoader loader = new FXMLLoader();
        loader.setLocation(this.getClass().getResource("stackPanel.fxml"));

        TextField loginPanel;
        FlowPane flowPane = loader.load();

        Scene scene = new Scene(flowPane);
        primaryStage.setScene(scene);
        primaryStage.setTitle("Logowanie");

        primaryStage.setWidth(500);
        primaryStage.setHeight(500);
        primaryStage.setResizable(false);

        primaryStage.show();

    }
}

和

import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.PasswordField;
import javafx.scene.control.TextField;
import javafx.stage.Modality;
import javafx.stage.Stage;
import javafx.stage.StageStyle;

import java.io.IOException;

public class ControlPanel {
    @FXML
    Button button;
    @FXML
    public void show(){
        System.out.println("Work");
    }

}

FXML

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.StackPane?>

<!--<FlowPane xmlns:fx="http://javafx.com/fxml/1"  >-->
<!--<children>-->
<!--<Label text="Login"/>-->
<!--<TextField fx:id="loginTextField"/>-->
<!--<Label text="Hasło"/>-->
<!--<PasswordField fx:id="passwordField"/>-->
<!--<Button fx:id="loginButton" text="Zaloguj"></Button>-->
<!--<Button fx:id="b1" text="Gabrys ma "/>-->
<!--</children>-->
<!--</FlowPane>-->

<?import javafx.scene.layout.FlowPane?>
<FlowPane prefHeight="334.0" prefWidth="445.0" xmlns:fx="http://javafx.com/fxml/1" >
    <children >

        <TextField fx:id="loginPanel" alignment="BOTTOM_LEFT" text="Login" />

        <Button fx:id="button" text="Logowanie" fx:controller="ControlPanel" onAction="#show"/>
    </children>

</FlowPane>