javafx/scenebuilder 文本字段或标签中的 mysql 数据

Question

有没有办法从 mysql 数据库中获取数据并在 javafx/scenebuilder 的文本字段中显示该数据的一部分？

我在 fxmlcontroller 中尝试了以下内容：

    @Override
public void initialize(URL url, ResourceBundle rb) {


    try {
        // Connection to the database
        Connection myConn = DriverManager.getConnection("jdbc:mysql://localhost:3306/demo", "root", "root");

        // Statement
        Statement myStmt = myConn.createStatement();
        // SQL query
        ResultSet myRs = myStmt.executeQuery("select * from test");
        // Result processing
        while (myRs.next()) {
            // testing if it gets the data from the db
            System.out.println(myRs.getString("firstname"));
            System.out.println(myRs.getString("lastname"));

            // attempt to put it in a textfield
           Labelnummer.setText(myRs.getString("firstname"));
           Tijd.setText(myRs.getString("lastname"));
        } 



    } catch (Exception exc) {
        exc.printStackTrace();
    }  

结果是一个 NullPointerException

我想我得到了连接并通过系统打印获取了数据，而不是将数据放入文本字​​段或标签的方法。

fxid 在 .fxml 中是正确的

我想我错过了一些东西，我只是不知道是什么。

先感谢您！

编辑：这是堆栈跟踪：

java.lang.NullPointerException
at com.mycompany.fastenyourseatbelts.DetailPaginaFXMLDocumentController.initialize(DetailPaginaFXMLDocumentController.java:98)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
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 com.mycompany.fastenyourseatbelts.FXMLController.Detail(FXMLController.java:27)
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.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769)
at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657)
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.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:49)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Node.fireEvent(Node.java:8413)
at javafx.scene.control.Button.fire(Button.java:185)
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
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.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$MouseHandler.process(Scene.java:3757)
at javafx.scene.Scene$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)

有问题的行是我尝试让文本字段获取数据的地方：

// attempt to put it in a textfield
       Labelnummer.setText(myRs.getString("firstname"));

下面是展示舞台和加载 fxml 的方法：

public class DetailPagina extends Application {

@Override
public void start(Stage stage) throws Exception {
    Parent root = FXMLLoader.load(getClass().getResource("DetailPaginaFXMLDocument.fxml"));

    Scene scene = new Scene(root);
    scene.getStylesheets().add("/styles/Style.css");

    stage.setScene(scene);
    stage.show();
}


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

}

Answer 1

没关系伙计们，显然文本字段本身没有正常工作。

我用新的 TextFields 尝试了它，它奏效了，谢谢你的帮助！

Answer 2

我有同样的问题，它对我不起作用。 我知道问题是因为我如何获得锚窗格。 这里的代码

public MainPage() {
        instance = this;
    }

    public static MainPage getInstance() {
        return instance;
    }

    public void createPagee(AnchorPane homeN, String loc) {

        try {
            homeN = FXMLLoader.load(getClass().getResource(loc));
            setNode(homeN);
        } catch (IOException e) {

            e.printStackTrace();
        }
    }

//This is my setNode method

private void setNode(Node node) {
        mainPane.getChildren().clear();
        mainPane.getChildren().add((Node) node);

        FadeTransition ft = new FadeTransition(Duration.millis(500));
        ft.setNode(node);
        ft.setFromValue(0.1);
        ft.setToValue(1);
        ft.setCycleCount(1);
        ft.setAutoReverse(false);
        ft.play();
    }

//And here how i accesses it

@FXML
    public void myBtn(ActionEvent event) {
        MainPage.getInstance().createPagee(CarsAnchor, "/GUI/car.fxml");
    }```