Java FX更改前一阶段场景中的标签文本 [英] Java FX change Label text in a previous stage scene

问题描述

我有一个 Main 类启动我的应用程序，该类具有在fxml中指定的 MainController 类。单击连接按钮时，将打开另一个具有不同场景和控制器的窗口。基于操作我想通过我的 MainController 更改 Label 文本值，但它不能按预期工作。请参阅下面的详细信息。

I have a Main class starting my application which has its MainController class specified in fxml. When clicking on Connect button another windows with different scene and controller is opened. Based on action I would like to change Label text value through my MainController, but it does not work as expected. See details below.

基本上我想在 MainController中更新 connectedLabel 上的文字/ code>来自 ConnectController 类的类，它不起作用。

Basically I would like to update text on connectedLabel in MainController class from ConnectController class and it does not work.

Main.java ：

public class Main extends Application {

    private static final Logger logger = Logger.getLogger(Main.class.getName());

    @Override
    public void start(Stage primaryStage) {
        try {
            logger.info("Application is starting");
            AnchorPane page = FXMLLoader.load(getClass().getResource("Main.fxml"));

            //BorderPane root = new BorderPane();
            //Scene scene = new Scene(root,400,400);

            Scene scene = new Scene(page);
            scene.getStylesheets().add(getClass().getResource("Main.css").toExternalForm());
            primaryStage.setScene(scene);

            primaryStage.setResizable(false);

            primaryStage.show();

        } catch(Exception e) {
            logger.warning(e.getMessage());
        }
    }

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

}

MainController .java ：

    public class MainController implements Initializable {

    private Context context = null;

    @FXML
    Label connectedLabel;
    @FXML
    Button connectButton;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        context = Context.getInstance();
    }

    public void setConnectedLabel(String name) {
        connectedLabel.setText(name);
        connectButton.setText("Disconnect");
    }

    @FXML
    public void connectTokenButton_onMouseClicked() {
        try {
            if (connectTokenButton.getText().equals("Disconnect")) {
                boolean disconnected = context.getToken().disconnectToken();
                if (disconnected) {
                    Alert alert = new Alert(AlertType.INFORMATION);
                    alert.setTitle("Disconnected");
                    alert.setHeaderText(null);
                    alert.setContentText("Succcessfully disconnected!");

                    alert.showAndWait();

                    connectedTokenLabel.setText("N/A");
                    connectTokenButton.setText("Connect");
                }
            } else {
                AnchorPane page = FXMLLoader.load(getClass().getResource("ConnectView.fxml"));

                Stage stage = new Stage();

                Scene scene = new Scene(page);
                scene.getStylesheets().add(getClass().getResource("ConnectView.css").toExternalForm());
                stage.setScene(scene);

                stage.setResizable(false);
                stage.initModality(Modality.APPLICATION_MODAL);
                stage.initOwner(connectedLabel.getScene().getWindow());
                stage.show();

                //Stage thisStage = (Stage) connectedTokenLabel.getScene().getWindow();
                //thisStage.close();
            }
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

ConnectController.java ：

public class ConnectController implements Initializable {

    private Context context = null;

    @FXML
    ComboBox<String> selectComboBox;
    @FXML
    PasswordField userPinPasswordField;
    @FXML
    Button cancelButton;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        context = Context.getInstance();
    }

    public void setMainC(Stage stage) {
        mainStage = stage;
    }

    @FXML
    private void connectToken_onMouseClicked() {
        String pin = userPinPasswordField.getText();
        boolean connected = context.connect(selectComboBox.getValue(), pin);        
        if (connected) {

            Alert alert = new Alert(AlertType.INFORMATION);
            alert.setTitle("Connected");
            alert.setHeaderText(null);
            alert.setContentText("Succcessfully connected!");

            alert.showAndWait();

            FXMLLoader myLoader = new FXMLLoader(getClass().getResource("Main.fxml"));
            MainController mainController = myLoader.getController();
            mainController.setConnectedTokenLabel(context.getConnectedName());

            Stage thisStage = (Stage) selectComboBox.getScene().getWindow();
            thisStage.close();
        }
    }
}

我做错了什么从不同的控制器调用 setConnectedLabel 方法？

What I am doing wrong when calling setConnectedLabel method from different controller?

推荐答案

FXMLLoader myLoader = new FXMLLoader(getClass().getResource("Main.fxml"));
MainController mainController = myLoader.getController();
mainController.setConnectedTokenLabel(context.getConnectedName());

不调用加载方法 FXMLLoader ，即使在fxml文件中指定了 fx：controller 属性，也不会创建控制器实例。

Without calling the load method of the FXMLLoader, no controller instance is created, even if the fx:controller attribute is specified in the fxml file.

然而，在 getController 之前调用加载将无济于事，因为fxml刚刚使用不同的控制器实例加载。

However calling load before getController will not help, since the fxml is just loaded again with a different controller instance.

你需要告诉 ConnectController 关于 MainController 它是从中创建的。 （参见传递参数JavaFX FXML ）

You need to "tell" the ConnectController about the MainController it was created from. (see Passing Parameters JavaFX FXML)

一种方法是将此代码添加到 ConnectController 类

One way would be to add this code to the ConnectController class

private MainController mainController;

public void setMainController(MainController mainController) {
    this.mainController = mainController;
}

并使用此字段代替 connectToken_onMouseClicked（）方法。

and use this field instead of the local variable in the connectToken_onMouseClicked() method.

要调用setter，请在 connectTokenButton_onMouseClicked（）中加载视图后访问控制器：

To call the setter, access the controller after loading the view in connectTokenButton_onMouseClicked():

FXMLLoader loader = new FXMLLoader(getClass().getResource("ConnectView.fxml"));
AnchorPane page = loader.load();
loader.<ConnectController>getController().setMainController(this);

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