如何从第二个控制器将值传递到已打开的阶段（第一个控制器）？

Question

我有两个控制器

1. FXMLDocumentController有TableView客户表。

2. NewCustomerController第二个控制器添加新行。

这是我的代码

FXML文档.fxml

<AnchorPane id="AnchorPane" prefHeight="283.0" prefWidth="437.0" xmlns="http://javafx.com/javafx/8.0.171" xmlns:fx="http://javafx.com/fxml/1" fx:controller="mytableview.FXMLDocumentController">

    <children>

        <Button fx:id="button" layoutX="309.0" layoutY="25.0" onAction="#handleButtonAction" text="New Customer" />

      <TableView fx:id="customerTable" layoutX="6.0" layoutY="61.0" prefHeight="215.0" prefWidth="426.0">

        <columns>

          <TableColumn fx:id="custname" prefWidth="75.0" text="Customer Name" />

          <TableColumn fx:id="city" prefWidth="75.0" text="City" />

        </columns>

         <columnResizePolicy>

            <TableView fx:constant="CONSTRAINED_RESIZE_POLICY" />

         </columnResizePolicy>

      </TableView>

    </children>

</AnchorPane>  

新客户.fxml

<AnchorPane id="AnchorPane" prefHeight="172.0" prefWidth="209.0" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8.0.171" fx:controller="com.newcustomer.NewCustomerController">

   <children>

      <Button layoutX="141.0" layoutY="129.0" mnemonicParsing="false" onAction="#newCustomer" text="Add" />

      <TextField fx:id="cNameTextField" layoutX="14.0" layoutY="26.0" promptText="Customer Name" />

      <TextField fx:id="custCityTextField" layoutX="14.0" layoutY="77.0" promptText="City" />

   </children>

</AnchorPane>

FXMLDocumentController.java

public class FXMLDocumentController implements Initializable {

private FXMLDocumentController documentController; //updated

@FXML

public TableView<Customer> customerTable;

@FXML

public TableColumn<Customer, String> custname;

@FXML

public TableColumn<Customer, String> city;  

@Override

public void initialize(URL url, ResourceBundle rb) { //updated

    custname.setCellValueFactory(new PropertyValueFactory<>("name"));

    city.setCellValueFactory(new PropertyValueFactory<>("city"));           

}

Answer 1

谈到您的实际问题，我注意到您的代码中存在三个问题。关于您在 newCustomer() 方法中获得的 NPE，您启动了 FXMLLoader 实例但未加载它。因此 getController() 为 null。要解决此问题，您需要在调用 getController() 之前先调用 load() 方法。public void newCustomer(ActionEvent e) throws IOException {    String name = cNameTextField.getText();    String stringCity = custCityTextField.getText();    Customer customer = new Customer(10, name, stringCity);    FXMLLoader fXMLLoader = new FXMLLoader(getClass().getResource("/mytableview/FXMLDocument.fxml"));    fXMLLoader.load(); // YOU ARE MISSING THIS LINE    FXMLDocumentController fXMLDocumentController = fXMLLoader.<FXMLDocumentController>getController();    fXMLDocumentController.inflateUI(customer); // Getting NPE at this line.}然而，上述修复是无用的，因为您正在创建一个未被使用的 FXMLDocumentController 的新实例（如 @kleopatra 指定的）。您必须实际传递要与之通信的控制器实例。您需要在 NewCustomerController 中创建该控制器的实例变量并设置它。@FXMLprivate void handleButtonAction(ActionEvent event) throws IOException {    FXMLLoader fXMLLoader = new FXMLLoader(getClass().getResource("/com/newcustomer/NewCustomer.fxml"));    Parent parent = fXMLLoader.load();    NewCustomerController controller = fXMLLoader.getController();    controller.setFXMLDocumentController(this); // Pass this controller to NewCustomerController    Stage stage = new Stage();    Scene scene = new Scene(parent);    stage.setScene(scene);    stage.show();}NewCustomerController.javaprivate FXMLDocumentController fXMLDocumentController;public void setFXMLDocumentController(FXMLDocumentController fXMLDocumentController) {    this.fXMLDocumentController = fXMLDocumentController;}public void newCustomer(ActionEvent e) throws IOException {    String name = cNameTextField.getText();    String stringCity = custCityTextField.getText();    Customer customer = new Customer(10, name, stringCity);    fXMLDocumentController.inflateUI(customer);//You are passing to the currently loaded controller}最后，您只需将 CellValueFactory 设置到 TableColumns 一次，而不是每次设置客户时。您可以将这两行移动到initialize() 方法。@Overridepublic void initialize(URL url, ResourceBundle rb) {    custname.setCellValueFactory(new PropertyValueFactory<>("name"));    city.setCellValueFactory(new PropertyValueFactory<>("city"));}