JavaFX pass values from child to parent

Question

I have one parent controller which contain one button. When I click on button it open new window and show some data into table. The code I have used for opening window is

Answer 1

In my example below, the account window (child/dialog) passes the newly selected account name back to the parent window when the save button is clicked. On the parent window ...

Stage nstage = new Stage();
                FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("Accounts.fxml"));
                Parent root = (Parent) fxmlLoader.load();
                AccountsController accController = fxmlLoader.getController();
                accController.dialogMode(); //Call a function in acconunt windoow to preset some fields

                Scene scene = new Scene(root);
                nstage.setTitle("Create Company Account");
                nstage.setScene(scene);

                Stage stage  = (Stage) src.getScene().getWindow();
                nstage.initOwner(stage);
                nstage.initModality(Modality.APPLICATION_MODAL);
                //nstage.initStyle(StageStyle.UNDECORATED); 
                nstage.show();

                nstage.setOnCloseRequest(new EventHandler<WindowEvent>(){
                    public void handle(WindowEvent we) {
                            txtCompany.setText( accController.lbl1.getText() );
                    }

                });

Answer 2

Expose a property in your child controller and observe it from the "parent" controller. There isn't really enough information in your question to give a precise answer, but it would look something like:

public class ChildController {

    @FXML
    private TableView<Customer> customerTable ;

    private final ReadOnlyObjectWrapper<Customer> currentCustomer = new ReadOnlyObjectWrapper<>();

    public ReadOnlyObjectProperty<Customer> currentCustomerProperty() {
        return currentCustomer.getReadOnlyProperty() ;
    }

    public Customer getCurrentCustomer() {
        return currentCustomer.get();
    }

    public void initialize() {
        // set up double click on table:

        customerTable.setRowFactory(tv -> {
            TableRow<Customer> row = new TableRow<>();
            row.setOnMouseClicked(e -> {
                if (row.getClickCount() == 2 && ! row.isEmpty()) {
                    currentCustomer.set(row.getItem());
                }
            }
        });

    }
}

and then you just do:

Stage stage = new Stage();
FXMLLoader fxmlLoader = new FXMLLoader(
        getClass().getResource("../layout/SearchCustomer.fxml"));
Parent parent = (Parent) fxmlLoader.load();

ChildController childController = fxmlLoader.getController();
childController.currentCustomerProperty().addListener((obs, oldCustomer, newCustomer) -> {
    // do whatever you need with newCustomer....
});

Scene scene = new Scene(parent);
stage.initModality(Modality.APPLICATION_MODAL);
stage.initOwner(parent.getScene().getWindow());
stage.setScene(scene);
stage.resizableProperty().setValue(false);
stage.showAndWait();

An alternative approach is to use a Consumer as a callback in the child controller:

public class ChildController {

    @FXML
    private TableView<Customer> customerTable ;

    private Consumer<Customer> customerSelectCallback ;

    public void setCustomerSelectCallback(Consumer<Customer> callback) {
        this.customerSelectCallback = callback ;
    }

    public void initialize() {
        // set up double click on table:

        customerTable.setRowFactory(tv -> {
            TableRow<Customer> row = new TableRow<>();
            row.setOnMouseClicked(e -> {
                if (row.getClickCount() == 2 && ! row.isEmpty()) {
                    if (customerSelectCallback != null) {
                        customerSelectCallback.accept(row.getItem());
                    }
                }
            }
        });

    }
}

And in this version you do

Stage stage = new Stage();
FXMLLoader fxmlLoader = new FXMLLoader(
        getClass().getResource("../layout/SearchCustomer.fxml"));
Parent parent = (Parent) fxmlLoader.load();

ChildController childController = fxmlLoader.getController();
childController.setCustomerSelectCallback(customer -> {
    // do whatever you need with customer....
});

Scene scene = new Scene(parent);
stage.initModality(Modality.APPLICATION_MODAL);
stage.initOwner(parent.getScene().getWindow());
stage.setScene(scene);
stage.resizableProperty().setValue(false);
stage.showAndWait();